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  • 1.
    Bergek, Christian
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och intensivvårdskliniken US.
    Zdolsek, Joachim H.
    Linköpings universitet, Institutionen för medicin och hälsa. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och intensivvårdskliniken US.
    Hahn, Robert
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för läkemedelsforskning. Region Östergötland, Sinnescentrum, Anestesi- och intensivvårdskliniken US. Linköpings universitet, Medicinska fakulteten. Research Unit, Södertälje Hospital, Södertälje, Sweden.
    Non-invasive blood haemoglobin and plethysmographic variability index during brachial plexus block2015Ingår i: British Journal of Anaesthesia, ISSN 0007-0912, E-ISSN 1471-6771, Vol. 114, nr 5, s. 812-817Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background Plethysmographic measurement of haemoglobin concentration (SpHb  ), pleth variability index (PVI), and perfusion index (PI) with the Radical-7 apparatus is growing in popularity. Previous studies have indicated that SpHb  has poor precision, particularly when PI is low. We wanted to study the effects of a sympathetic block on these measurements.

    Methods Twenty patients underwent hand surgery under brachial plexus block with one Radical-7 applied to each arm. Measurements were taken up to 20 min after the block had been initiated. Venous blood samples were also drawn from the non-blocked arm.

    Results During the last 10 min of the study, SpHb  had increased by 8.6%. The PVI decreased by 54%, and PI increased by 188% in the blocked arm (median values). All these changes were statistically significant. In the non-blocked arm, these parameters did not change significantly.

    Conclusions Brachial plexus block significantly altered SpHb  , PVI, and PI, which indicates that regional nervous control of the arm greatly affects plethysmographic measurements obtained by the Radical-7. After the brachial plexus block, SpHb  increased and PVI decreased.

  • 2.
    Bergek, Christian
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet.
    Zdolsek, Joachim
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Hahn, Robert G
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Accuracy of noninvasive haemoglobin measurement by pulse oximetry depends on the type of infusion fluid2012Ingår i: European Journal of Anaesthesiology, ISSN 0265-0215, E-ISSN 1365-2346, Vol. 29, nr 12, s. 586-592Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Context: Measurement of blood haemoglobin concentration by pulse oximetry could be of value in determining when erythrocytes should be transfused during surgery, but the effect of infusion fluids on the results is unclear.

    Objective: To study the effect of crystalloid and colloid fluid on the accuracy (bias) and precision of pulse oximetry haemoglobin estimation to indicate the venous haemoglobin concentration in volunteers.

    Design: Open interventional crossover study.

    Setting: Single university hospital.

    Participants: Ten male volunteers aged 18–28 (mean 22) years.

    Interventions: Each volunteer underwent three infusion experiments on separate days and in random order. The infusions were Ringer's acetate (20 ml kg−1), hydroxyethyl starch 130/0.4 (10 ml kg−1) and a combination of both.

    Results: At the end of the infusions of Ringer's acetate, pulse oximetry haemoglobin concentration had decreased more than the true haemoglobin concentration (15 vs. 8%; P < 0.005; n  = 10) whereas starch solution decreased pulse oximetry haemoglobin concentration less than true haemoglobin concentration (7 vs. 11%; P < 0.02; n  = 20). The same differences were seen when the fluids were infused separately and when they were combined. The overall difference between all 956 pairs of pulse oximetry haemoglobin concentration and true haemoglobin concentrations (the bias) averaged only −0.7 g l−1 whereas the 95% prediction interval was wide, ranging from −24.9 to 23.7 g l−1. In addition to the choice of infusion fluid, the bias was strongly dependent on the volunteer (each factor, P < 0.001).

    Conclusion: The bias of measuring haemoglobin concentration by pulse oximetry is dependent on whether a crystalloid or a colloid fluid is infused.

  • 3.
    Berndtson, Dan
    et al.
    Gällivare Hospital, Sweden.
    Olsson, Joel
    Gällivare Hospital, Sweden.
    Hahn, Robert G.
    Södertälje Hospital, Sweden.
    Hypovolaemia after glucose/insulin infusions in volunteers2008Ingår i: Clinical Science, ISSN 0143-5221, E-ISSN 1470-8736, Vol. 115, nr 12, s. 371-378Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High-dose intravenous infusion of 5% glucose promotes rebound hypoglycaemia and hypovolaemia in healthy volunteers. To study whether such effects occur in response to glucose/insulin, 12 healthy firemen (mean age, 39 years) received three infusions over 1-2 h that contained 20 ml of 2.5% glucose/kg of body weight, 5 ml of 10% glucose/kg of body weight with 0.05 unit of rapid-acting insulin/kg of body weight, and 4 ml of 50% glucose/kg of body weight with 1 unit of insulin/kg of body weight. The plasma glucose concentration and plasma dilution were compared at 5-10 min intervals over 4 h. Regardless of the amount of administered fluid and whether insulin was given, the plasma glucose concentration decreased to hypoglycaemic levels within 30 min of the infusion ending. The plasma dilution closely mirrored plasma glucose and became negative by approx. 5%, which indicates a reduction in the plasma volume. These alterations were only partially restored during the follow-up period. A linear relationship between plasma glucose and plasma dilution was most apparent when the infused glucose had been dissolved in only a small amount of fluid. For the strongest glucose/insulin solution, this linear relationship had a correlation coefficient of 0.77 (n=386, P<0.0001). The findings of the present study indicate that a redistribution of water due to the osmotic strength of the glucose is the chief mechanism accounting for the hypovolaemia. It is concluded that infusions of 2.5%, 10% and 50% glucose, with and without insulin, in well-trained men were consistently followed by long-standing hypoglycaemia and also by hypovolaemia, which averaged 5%. These results emphasize the relationship between metabolism and fluid balance.

  • 4.
    Borup, T.
    et al.
    Hvidovre University Hospital, Denmark.
    Hahn, Robert G.
    Clinical Research Centre, Södertälje, Sweden.
    Holte, K.
    Hvidovre University Hospital, Denmark.
    Ravn, L.
    Hvidovre University Hospital, Denmark.
    Kehlet, H.
    Rigshospitalet, Denmark.
    Intra-operative colloid administration increases the clearance of a post-operative fluid load2009Ingår i: Acta Anaesthesiologica Scandinavica, ISSN 0001-5172, E-ISSN 1399-6576, Vol. 53, nr 3, s. 311-317Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    BACKGROUND: It is unknown whether an intra-operative colloid infusion alters the dynamics of a crystalloid load administered post-operatively.

    METHODS: Ten patients received 12.5 ml/kg of Ringer's lactate over 30 min 1-3 days before and 4 h after laparoscopic cholecystectomy, during which 10 ml/kg of a colloid solution, hydroxyethylstarch (HES 130/0.4), was infused. The total body clearance of the pre- and post-operative test infusions was taken as the ratio between the urinary excretion and the Hb-derived dilution of venous plasma over 150 min. The plasma clearance of the infused fluid was calculated using volume kinetics based on the plasma dilution alone. The pre-operative plasma clearance was compared with the post-operative plasma clearance and patients served as their own control.

    RESULTS: The urinary excretion averaged 350 ml for the pre-operative infusion and 612 ml post-operatively, which corresponds to 46% and 68% of the pre- and post-operative infusions, respectively. The total body clearance of the crystalloid fluid was 30 ml/min before surgery and 124 ml/min after surgery (P<0.01). The plasma clearance, as obtained from the plasma dilution alone, was 28 and 412 ml/min, respectively. The maximal increase in plasma volume was 410 ml pre-operatively vs. 220 ml post-operatively.

    CONCLUSIONS: Infusion of a colloid solution in combination with a crystalloid during laparoscopic cholecystectomy increased the plasma clearance of a post-operative crystalloid infusion.

  • 5.
    Brauer, Kirk I
    et al.
    University of Texas Medical Branch.
    Brauer, Lance P
    University of Texas Medical Branch.
    Prough, Donald S
    University of Texas Medical Branch.
    Rodhe, Peter
    Karolinska Institute.
    Hahn, Robert G
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Traber, Daniel L
    University of Texas Medical Branch.
    Traber, Lilian D
    University of Texas Medical Branch.
    Svensen, Christer H
    Karolinska Institute.
    Hypoproteinemia does not alter plasma volume expansion in response to a 0.9% saline bolus in awake sheep2010Ingår i: CRITICAL CARE MEDICINE, ISSN 0090-3493, Vol. 38, nr 10, s. 2011-2015Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Objective: To test the hypothesis that hypoproteinemia reduces plasma volume expansion produced by a bolus of crystalloid solution given to awake sheep. Design: Prospective and observational. Setting: Laboratory. Subjects: Five female merino sheep (n = 5) weighing 37 +/- 3 kg were anesthetized. Interventions: Each animal was subjected to a 5-day test period: day 1: 50 mL/min 0.9% saline infusion over 20 mins. Days 2-4: daily plasmapheresis and replacement of the shed plasma with 6 L of 0.9% saline were performed in increments. Measurements and Main Results: Fractional plasma volume expansion after rapid infusion of saline on days 1 and 5 was calculated from changes in hemoglobin concentration. There was a significant reduction in total plasma protein concentration after plasmapheresis (p andlt; .05). Colloid osmotic pressures were also significantly lowered (p andlt; .05). A crystalloid infusion of 0.9% saline did not alter any of these values compared with baseline. The hemodynamic measurements did not show significant differences between the experiments. The plasma volume expansion reached approximately 20% at the end of infusion and stayed at 10-15% during the experiments. No difference was found in plasma volume expansion produced by a bolus of 50 mL/min of 0.9% in the hypoproteinemic state when compared with the euproteinemic state (p = .61). No difference in cumulative urinary output was found between the two states. Conclusions: In contrast to our hypothesis, severe acute hypoproteinemia does not reduce plasma volume expansion in response to 50 mL/min 0.9% saline infusion in nonspleenectomized sheep when compared with the resultant plasma volume expansion after a 50 mL/min of 0.9% infusion in the euproteinemic state.

  • 6.
    Drobin, D.
    et al.
    Karolinska University Hospital, Huddinge, Stockholm, Sweden.
    Hjelmqvist, H.
    Karolinska University Hospital, Huddinge, Stockholm, Sweden.
    Piros, D.
    South Hospital, Stockholm, Sweden.
    Hahn, Robert G.
    Södertälje Hospital, Sweden.
    Monitoring of fluid absorption with nitrous oxide during transurethral resection of the prostate2008Ingår i: Acta Anaesthesiologica Scandinavica, ISSN 0001-5172, E-ISSN 1399-6576, Vol. 52, nr 4, s. 509-513Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    BACKGROUND: The fluid absorption that occurs during transurethral resection of the prostate (TURP) can be indicated and quantified by the ethanol method. Recently, nitrous oxide (N(2)O) was tested in animals and volunteers and seemed to be more accurate and safe. The present study compared these two methods in surgical patients.

    METHODS: Eighty-six TURPs were performed at two hospitals using an irrigating fluid that contained 3% mannitol, 1% ethanol and 0.004% N(2)O (40 ml/l). The ethanol concentration was measured by end-expiratory tests every 10 min. The N(2)O concentration was measured by a flared nasal cannula every second. Fluid absorption was calculated based on a regression equation (ethanol method) from the area under the curve based on the samples where CO(2) >median (N(2)O method).

    RESULTS: Thirteen patients (15%) absorbed >300 ml of fluid as indicated by the ethanol method. The median volume was 707 ml (range 367-1422). Ethanol yielded higher figures for fluid absorption up to 700-800 ml, whereafter the N(2)O method indicated that the absorption was larger. Over the entire range, the mean difference between the two methods at the end of any 10-min period of TURP was only +45 ml, although the 95% limits of agreement were quite separated (-479 to +569 ml).

    CONCLUSIONS: The N(2)O method does not require forced breath sampling and was successfully apply clinically. However, there was a dose-dependent difference in result between the ethanol and N(2)O methods, which markedly separated the limits of agreement for a wider range of fluid absorption events.

  • 7.
    Drobin, Dan
    et al.
    South Hospital, Stockholm, Sweden.
    Sjöstrand, Fredrik
    South Hospital, Stockholm, Sweden.
    Piros, David
    South Hospital, Stockholm, Sweden.
    Hedin, Annika
    South Hospital, Stockholm, Sweden.
    Heinius, Göran
    South Hospital, Stockholm, Sweden.
    Hahn, Robert G
    South Hospital, Stockholm, Sweden.
    Tranexamic acid does not prevent rebleeding in an uncontrolled hemorrhage porcine model2005Ingår i: Journal of Trauma, ISSN 0022-5282, E-ISSN 1529-8809, Vol. 59, nr 4, s. 976-983Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    BACKGROUND: Fluid resuscitation after uncontrolled hemorrhage might promote rebleeding and irreversible shock. Tranexamic acid is a procoagulant drug that limits blood loss after surgery of the hip, knee, and heart. We hypothesized that pretreatment with tranexamic acid reduces the rebleeding in uncontrolled hemorrhage and thereby allows safe administration of crystalloid fluid resuscitation.

    METHODS: A 120-minute intravenous infusion of 100 mL/kg of Ringer's solution was given to 24 pigs (mean weight, 20 kg) 10 minutes after lacerating the infrarenal aorta. The animals were randomized to receive an intravenous injection of 15 mg/kg of tranexamic acid or placebo just before starting the resuscitation. Rebleeding events were monitored by two ultrasonic probes positioned proximal and distal to the laceration.

    RESULTS: Tranexamic acid had no effect on the number of rebleeding events, bled volume, or mortality. The initial bleeding stopped within 4 minutes after the injury. The five animals that died suffered from 4.4 rebleeding events on average, which tripled the total blood loss, whereas the survivors had only 1.3 such events during fluid resuscitation (p < 0.02). At autopsy, death was associated with a larger total hemorrhage; the blood recovered from the abdomen weighed 1.4 kg (median) in nonsurvivors and 0.6 kg in survivors (p < 0.001), with the difference being attributable to rebleeding.

    CONCLUSION: Rebleeding events increased the amount of blood lost and the mortality in uncontrolled aortic hemorrhage. Tranexamic acid offered no benefit.

  • 8.
    Ewaldsson, C-A
    et al.
    South Hospital, and Karolinska Institute, Stockholm, Sweden.
    Hahn, Robert G.
    South Hospital, and Karolinska Institute, Stockholm, Sweden.
    Bolus injection of Ringer's solution and dextran 1 kDa during induction of spinal anesthesia2005Ingår i: Acta Anaesthesiologica Scandinavica, ISSN 0001-5172, E-ISSN 1399-6576, Vol. 49, nr 2, s. 152-159Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    BACKGROUND: Arterial hypotension following induction of spinal anesthesia is difficult to prevent with infusion fluids. In a randomized, unblinded and controlled study we evaluated whether a rapid fluid administration planned according to volume kinetic analysis is followed by a more stable blood pressure.

    METHODS: Spinal anesthesia was induced in 75 surgical patients, using one of three different fluid regimens: intravenous 'bolus injection' of 5 ml kg(-1) of Ringer's acetate over 3 min, 2 ml kg(-1) of low-molecular weight (1 kDa) dextran over 3 min, or a constant-rate infusion of 15 ml kg(-1) of Ringer's acetate over 40 min (controls). The kinetics of the fluid was studied in five patients in each group and also in eight volunteers.

    RESULTS: The decrease in mean arterial pressure averaged 28%, 27% and 26%, respectively, and was fully developed 16 min after the induction. The height of the block, but not the fluid programme, correlated with the hypotension. Nausea or near-fainting associated with marked hypotension or bradycardia was recorded in none, five (20%) and two (8%) of the patients, respectively. Both bolus injections were followed by translocation of fluid from the peripheral tissues to the bloodstream, which maintained the plasma dilution at about 10% for at least 30 min until surgery began.

    CONCLUSION: A brisk infusion of Ringer's solution or dextran 1 kDa over 3 min was followed by the same decrease in arterial pressure as a longer and 3-5-times larger infusion of Ringer's solution over 40 min during induction of spinal anesthesia.

  • 9.
    Ewaldsson, Carl-Arne
    et al.
    South Hospital, Karolinska Institute, Stockholm, Sweden.
    Hahn, Robert G
    South Hospital, Karolinska Institute, Stockholm, Sweden.
    Kinetics and extravascular retention of acetated ringer's solution during isoflurane or propofol anesthesia for thyroid surgery2005Ingår i: Anesthesiology, ISSN 0003-3022, E-ISSN 1528-1175, Vol. 103, nr 3, s. 460-469Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    BACKGROUND: In sheep, isoflurane causes extravascular accumulation of infused crystalloid fluid. The current study evaluates whether isoflurane has a greater tendency than propofol to cause extravascular retention in surgical patients.

    METHODS: Thirty patients undergoing thyroid surgery lasting for 143 +/- 32 min (mean +/- SD) received an intravenous infusion of 25 ml/kg acetated Ringer's solution over 30 min. Anesthesia was randomized to consist of isoflurane or propofol supplemented by fentanyl. The distribution and elimination of the infused fluid was estimated using volume kinetics based on the fractional dilution of blood hemoglobin over 150 min. Extravascular retention of infused fluid was taken as the difference between the model-predicted elimination and the urinary excretion. The sodium and fluid balances were measured.

    RESULTS: The fractional plasma dilution increased gradually to approximately 30% during the infusion and thereafter remained at 15-20%. Urinary excretion averaged 11% of the infused volume. Mean arterial pressure was 10 mmHg lower in the isoflurane group (P < 0.001). The excess fluid volumes in the central and peripheral functional body fluid spaces were virtually identical in the groups. The sum of water losses by evaporation and extravascular fluid retention amounted to 2.0 +/- 2.5 ml/min for isoflurane and 2.2 +/- 2.1 ml/min for propofol. The sodium balance refuted that major fluid shifts occurred between the extracellular and intracellular spaces.

    CONCLUSIONS: The amount of evaporation and extravascular retention of fluid was small during thyroid surgery, irrespective of whether anesthesia was maintained by isoflurane or propofol.

  • 10.
    Ewaldsson, Carl-Arne
    et al.
    South Hospital, Stockholm, Sweden.
    Vane, Luiz A.
    University of Texas Medical Branch, Galveston, USA.
    Kramer, George C.
    University of Texas Medical Branch, Galveston, USA.
    Hahn, Robert G.
    South Hospital, Stockholm, Sweden.
    Adrenergic drugs alter both the fluid kinetics and the hemodynamic responses to volume expansion in sheep2006Ingår i: Journal of Surgical Research, ISSN 0022-4804, E-ISSN 1095-8673, Vol. 131, nr 1, s. 7-14Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    BACKGROUND: Plasma volume expansion is often performed during adrenergic therapy in the intensive care unit, but little is known about their combined effects.

    MATERIALS AND METHODS: The influence of three adrenergic drugs (50 microg/kg/min of dopamine, 0.1 microg/kg/min of isoprenaline, or 3 microg/kg/min of phenylephrine) on the relationship between plasma dilution (an index of volume expansion) and the central hemodynamic responses to volume loading with 24 ml/kg of 0.9% saline were evaluated in 6 adult sheep. Kinetic analysis was also applied to the data on plasma dilution and the urinary excretion measured during and after volume loading.

    RESULTS: The adrenergic agents markedly changed the baseline values for all hemodynamic parameters. The kinetic analysis showed that phenylephrine, which is an alpha-adrenergic receptor agonist, promoted renal excretion of infused fluid at the expense of fluid distribution to the periphery (P < 0.05 versus controls). Isoprenaline, which stimulates adrenergic beta-receptors, had the opposite effect. During volume expansion, cardiac atrial pressures increased by 25 to 90%, cardiac output by 13-80% and the arterial pressures by 2 to 22%. Plasma dilution during and after volume loading correlated, in a linear fashion, with these hemodynamic responses. The correlations were strong (r > 0.80) in the control and phenylephrine groups, but weaker in the dopamine and isoprenaline groups. Dopamine was associated with the most variable hemodynamic responses overall.

    CONCLUSIONS: Adrenergic drugs altered the hemodynamics at baseline (direct effects), changed the distribution and elimination of infused 0.9% saline (indirect effects) and, finally, modified most hemodynamic responses to plasma dilution (interaction effects).

  • 11.
    Fagerstrom, Tim
    et al.
    Karolinska Institute.
    Nyman, Claes R.
    Karolinska Institute.
    Hahn, Robert
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Complications and Clinical Outcome 18 Months After Bipolar and Monopolar Transurethral Resection of the Prostate2011Ingår i: Journal of endourology, ISSN 0892-7790, E-ISSN 1557-900X, Vol. 25, nr 6, s. 1043-1049Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose: To compare bipolar resection with the conventional monopolar transurethral resection of the prostate (TURP) with respect to peri- and postoperative complications and long-term outcome. Patients and Methods: Patients with consecutive benign prostatic hyperplasia needing surgery (n = 185) from the hospitals waiting list were randomized to TURP using either a bipolar or a monopolar system. Peri-and postoperative parameters were monitored, complications were registered, and timed micturition/International Prostate Symptom Score (TM/IPSS) forms were collected at 3 and 6 weeks and at 6 and 18 months. Results: Bipolar surgery was followed by a 16% to 20% higher percentage of the patients reporting ongoing improvement (fractional IPSS change greater than2) at 3 and 6 weeks after the surgery (p less than 0.05). There were fewer readmissions in the bipolar group than in the monopolar (5 vs. 13, p less than 0.05). No differences between the groups with respect to hospital stay and catheter duration was recorded. Bipolar and monopolar TURP resulted in marked and sustained improvements of IPSS, bother score, and TM. Conclusions: Bipolar TURP, using the transurethral resection in saline (TURis) system, resulted in significantly fewer postoperative readmissions, faster postoperative recovery, and equally long-lasting good results in TM/IPSS and bother score, as in monopolar TURP.

  • 12.
    Fagerstrom, Tim
    et al.
    Karolinska Institute, Sweden .
    Nyman, Claes R
    Karolinska Institute, Sweden .
    Hahn, Robert G
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Degree of Vaporization in Bipolar and Monopolar Resection2012Ingår i: Journal of endourology, ISSN 0892-7790, E-ISSN 1557-900X, Vol. 26, nr 11, s. 1473-1477Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose: To compare the in vitro degree of vaporization in bipolar and monopolar resection. less thanbrgreater than less thanbrgreater thanMaterials and Methods: Using either a bipolar system or a monopolar system, samples of chicken muscle and lamb kidney were resected in an isolated basin and then desiccated in an incubator. The percentual degree of vaporization for each sample was obtained as a difference between the total fresh weight of the sample and the calculated fresh weights of the resected tissue and remains. less thanbrgreater than less thanbrgreater thanResults: Reference samples showed that the water content was 73% in muscle and 77% in kidney. More muscle (mean 52%) than kidney (32%; P andlt; 0.0001) tissue was vaporized. The fraction of vaporized tissue was significantly higher in the bipolar technique. In muscle, the differences between monopolar and bipolar were 17% (P andlt; 0.05) and 26% (P andlt; 0.001), respectively, depending on the type of irrigation used. For kidney, the differences were 27% (P andlt; 0.01) and 34% (P andlt; 0.01), respectively. Further exploration of the degree of vaporization when using the bipolar resection showed that the choice of loop (P andlt; 0.0001), fluid (P andlt; 0.03), and tissue (P andlt; 0.0001) were all independently associated with the degree of vaporization. less thanbrgreater than less thanbrgreater thanConclusions: This study indicated that vaporization removes 50% more tissue than the weight of the resected tissue during conventional tissue resection. Bipolar standard loop resection resulted in a significantly higher degree of vaporization in both muscle and kidney than did monopolar technique. Bipolar resection worked satisfactorily in Ringers acetate.

  • 13.
    Fagerström, Tim
    et al.
    Karolinska Institutet, Södersjukhuset, Stockholm, Sweden.
    Nyman, Claes R.
    Karolinska Institutet, Södersjukhuset, Stockholm, Sweden.
    Hahn, Robert G.
    Clinical Research Centre, Södertälje Hospital, Sweden.
    Bipolar transurethral resection of the prostate causes less bleeding than the monopolar technique: a single-centre randomized trial of 202 patients2010Ingår i: BJU International, ISSN 1464-4096, E-ISSN 1464-410X, Vol. 105, nr 11, s. 1560-1564Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    OBJECTIVE: To compare bipolar with the conventional monopolar transurethral resection of the prostate (TURP) for blood loss and speed of resection.

    PATIENTS AND METHODS: In all, 202 consecutive patients from the hospital waiting list were randomized to undergo TURP using either a bipolar system (Surgmaster TURis, Olympus, Tokyo, Japan) or a monopolar system (24 F, Storz, Tübingen, Germany). The blood loss during and after surgery was measured using a photometer. Other variables compared included indices of resection speed and transfusion rate.

    RESULTS: There were no statistically significant differences in operative duration, resection weight, resection speed or radicality of resection. However, the median blood loss was 235 mL for the bipolar and 350 mL for monopolar TURP (P < 0.001). The decrease in blood haemoglobin concentration during the day of surgery was smaller in the bipolar group (5.5% vs 9.6%P < 0.001). Fewer patients were transfused with erythrocytes (4% vs 11%, P < 0.01), which can be explained by the much lower 75th percentile for blood loss in the bipolar group (at 472 vs 855 mL, respectively).

    CONCLUSIONS: Bipolar TURP using the TURis system was performed with the same speed as monopolar TURP but caused 34% less bleeding, the difference being greatest (81%) for the largest blood losses. Bipolar TURP also required fewer erythrocyte transfusions than the conventional monopolar technique.

  • 14.
    Hahn, R G.
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för läkemedelsforskning. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och intensivvårdskliniken US.
    Letter: Haemodilution made difficult2013Ingår i: British Journal of Anaesthesia, ISSN 0007-0912, E-ISSN 1471-6771, Vol. 111, nr 4, s. 679-680Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    n/a

  • 15.
    Hahn, Robert
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Body volumes and fluid kinetics2011Ingår i: Clinical Fluid Therapy in the Perioperative Setting / [ed] Robert G. Hahn, Cambridge: Cambridge University Press , 2011, s. 127-136Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    The sizes of body fluid volumes have been measured under steady state conditions by the use of tracer methods. In an adult weighing 70 kg, they average 3 L for the plasma, 11 L for the interstitial fluid, and 28 L for the intracellular fluid (ICF) volume. Hence, the sum of the plasma and interstitial fluid volumes (the extracellular fluid, or ECF, volume) amounts to 14 L, or 20% of the body weight.

    Substances known to distribute solely within one body fluid compartment can be injected and the size of the compartment be calculated by means of dilution of the substance.

    The total body water (sum of ECF and ICF) can be measured with water isotopes, which include tritium (radioactive) and deuterium (not radioactive). The plasma volume has frequently been measured by radioactive iodated albumin.

    The indocyanine green (ICG) is a dye that binds to plasma globulins. The half-life is only 3 min due to rapid uptake by the liver. Therefore, ICG can be used both to measure the liver blood flow and the plasma volume.

    The volume effect of an infusion fluid implies how much of the infused volume that expands the blood volume. A simplistic approach to quantify the volume effect of an infusion fluid is to measure the Hb concentration before and after the infusion. Hb mathematics can also be elaborated upon to create a pharmacokinetic system for the analysis and simulation of the distribution and elimination if infusion fluids, an approach called volume kinetics.

  • 16.
    Hahn, Robert
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Colloid fluids2011Ingår i: Clinical Fluid Therapy in the Perioperative Setting / [ed] Robert G. Hahn, Cambridge: Cambridge University Press , 2011, s. 11-17Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    The term colloid fluid refers to a sterile water solution with macromolecules added that pass the capillary wall only with great difficulty. The osmotic strength of the macromolecules is not great and, therefore, a colloid fluid must also contain electrolytes to be non-hemolytic. As long as macromolecules reside inside the capillary wall their contribution to the total osmolality (the colloid osmotic pressure) is still sufficient to distribute a large proportion of the infused fluid volume inside the bloodstream. 

    Colloid fluids are used as plasma volume expanders and have more long-lasting effect than crystalloid fluids. They carry a risk of allergic reactions not shared by crystalloid fluids.

    Albumin is the most abundant protein in plasma and, therefore, has an important role in maintaining the intravascular colloid osmotic pressure.

    Long chains of glucose molecules (polysaccharides) are synthesized by bacteria to serve as macromolecules in the group of infusion fluids called the dextrans.

    Hydroxyethyl starch (HES) also consists of polysaccharides and is prepared from plants, such as grain or maize. The variability in chemical composition determines the differences in clinical effect between the solutions. Hetastarch contains the largest molecules (450 kD) and pentastarch intermediate-sized molecules (260 kD). The most recently developed HES preparations have an even lower molecular size, 130 kD on the average.

     

  • 17.
    Hahn, Robert
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Crystalloid fluids2011Ingår i: Clinical Fluid Therapy in the Perioperative Setting   / [ed] Robert G. Hahn, Cambridge: Cambridge University Press , 2011, s. 1-10Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    The term crystalloid fluid refers to sterile water solutions that contain small molecules, such as salt and glucose, which are able to crystallize. These solutes easily pass though the capillary membrane, which is the thin fenestrated endothelium that divides the plasma volume (PV) from the interstitial fluid volume. This process of solute distribution brings along water. Hence, the volume of a crystalloid fluid is spread throughout the extracellular fluid (ECF) space. 

    Ringer´s solution is a composition created by Sydney Ringer in the 1880s to be as similar as possible to the ECF. Hartmann later added a buffer, lactate, to the fluid and made it “Hartmann´s solution” or “lactated “Ringer´s solution”. Ringer solutions distribute from the plasma to the interstitial fluid space in a process that requires 25-30 min to be completed. The half-life in plasma is approximately 8 min. In contrast, elimination is greatly retarded during surgery where Ringer´s always exhibit two-compartment kinetics.

    Glucose (dextrose) solutions are used to administer calories to prevent starvation, and also to provide body water. They are the only available infusion fluids that add volume to both the ECF and the ICF volumes. Infused glucose distributes rapidly over 2/3 of the expected ECF space. Elimination occurs by insulin-dependent uptake to the body cells. The half-life is 15 min in healthy volunteersbut twice as long during surgery. The basic need for glucose in an adult corresponds to 4 L of 5% glucose per 24 hours (800 kcal) which prevents blunt starvation while not providing adequate nutrition.

    The hypertonic nature of 15% mannitol has made it a means of acutely reducing the intracranial pressure in patients with head trauma.

  • 18.
    Hahn, Robert
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för läkemedelsforskning. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Editorial Material: Why are crystalloid and colloid fluid requirements similar during surgery and intensive care?2013Ingår i: European Journal of Anaesthesiology, ISSN 0265-0215, E-ISSN 1365-2346, Vol. 30, nr 9, s. 515-518Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    n/a

  • 19.
    Hahn, Robert
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för läkemedelsforskning. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Anestesi- och intensivvårdskliniken US.
    Fluid absorption and the ethanol monitoring method2015Ingår i: Acta Anaesthesiologica Scandinavica, ISSN 0001-5172, E-ISSN 1399-6576, Vol. 59, nr 9, s. 1081-1093Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    BackgroundFluid absorption is a well-known complication of endoscopic surgeries, such as transurethral prostatic resection and transcervical endometrial resection. Absorption of electrolyte-free fluid in excess of 1L, which occurs in 5% to 10% of the operations, markedly increases the risk of adverse effects from the cardiovascular and neurological systems. Absorption of isotonic saline, which is used with the new bipolar resection technique, will change the scenario of adverse effects in a yet unknown way. Hyponatremia no longer occurs, but marking the saline with ethanol reveals that fluid absorption occurs just as much as with monopolar prostate resections. MethodsEthanol monitoring is a method for non-invasive indication and quantification of fluid absorption that has been well evaluated. By using an irrigating fluid that contains 1% of ethanol, updated information about fluid absorption can be obtained at any time perioperatively by letting the patient breathe into a hand-held alcolmeter. ResultsRegression equations and nomograms with variable complexity are available for estimating how much fluid has been absorbed, both when the alcolmeter is calibrated to show the blood ethanol level and when it is calibrated to show the breath ethanol concentration. Examples of how such estimations should be performed are given in this review article. ConclusionsThe difficulty is that the anesthesiologist must be aware of how the alcolmeter is calibrated (for blood or breath) and be able to distinguish between the intravascular and extravascular absorption routes, which give rise to different patterns and levels of breath ethanol concentrations.

  • 20.
    Hahn, Robert
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för läkemedelsforskning. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Glycine 1.5% for Irrigation Should Be Abandoned2013Ingår i: Urologia internationalis, ISSN 0042-1138, E-ISSN 1423-0399, Vol. 91, nr 3, s. 249-255Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Background: Glycine 1.5% has long maintained a dominating role as an irrigating solution for monopolar transurethral resection of the prostate (TURP), as well as for certain other transurethral procedures. Materials and Methods: This review summarizes the findings of systematic experimental and clinical studies in which glycine 1.5% for irrigation was infused/absorbed and the outcome compared to at least one other irrigating fluid, including the isotonic saline used for bipolar TURP. Results: There were 11 studies in animals, 3 in volunteers and 6 in patients undergoing TURP. With only one exception, which is probably due to low power, these studies either show a poorer outcome after administration or absorption of glycine solution or else that glycine 2.2% is more toxic than glycine 1.5%. The poorer outcomes consisted of more tissue damage or higher mortality (animals) or more symptoms (volunteers and patients). Conclusion: The safety of monopolar TURP would be improved by replacing glycine 1.5% with some other electrolyte-free fluid. The author argues that glycine 1.5% should be abandoned completely.

  • 21.
    Hahn, Robert
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Irrigating fluids2011Ingår i: Clinical Fluid Therapy in the Perioperative Setting / [ed] Robert G. Hahn, Cambridge: Cambridge University Press , 2011, s. 148-156Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Patients developing overt symptoms due to absorption of irrigating fluid were first described in connection with transurethral resection of the prostate (TURP). This “transurethral resection (TUR) syndrome” soon proved to be due to uptake of more than 3 L of irrigant.

    The most commonly used irrigating fluids used today contain glycine, sorbitol or mannitol, to prevent hemolysis in case they are absorbed. These fluids are intended for monopolar electrocautery.

    Symptoms of fluid absorption occurs in between 1% and 8% of the TURPs performed. Absorption in excess of 1Lof glycine solution is associated with a statistically increased risk of symptoms. This has been reported in between 5% and 20% of the TURPs performed. Extravasation is the cause in about 20% of these patients.    

    The TUR syndrome induced by an electrolyte-free irrigating fluid has a complex pathophysiology. Key elements comprise a two-stage cardiovascular disturbance, hyponatremia, and cerebral edema.

    Absorption of electrolyte-free irrigating fluid can be estimated by measuring serum sodium at the very end of surgery. Ethanol has been added to the irrigating fluid to a concentration of 1% and the body concentration measured used an index of the fluid absorption. Both experimental and clinicalstudies support the usefulness of treating the TUR syndrome with hypertonic saline. Supporting the hemodynamics with adrenergic drugs is also warranted.

    Large-scale fluid absorption with normal saline is a possibility during bipolar resection. Treatment should probably be limited to general supportive measures and diuretics. Hypertonic saline is not indicated.

  • 22.
    Hahn, Robert
    Södertälje sjukhus.
    Mer om stärkelselösning och njurskador2012Ingår i: Läkartidningen, ISSN 0023-7205, E-ISSN 1652-7518, Vol. 109, nr 51-52, s. 2342-Artikel i tidskrift (Övrigt vetenskapligt)
  • 23.
    Hahn, Robert
    Södertälje sjukhus.
    Natriumklorid är en olämplig infusionsvätska2012Ingår i: Läkartidningen, ISSN 0023-7205, E-ISSN 1652-7518, Vol. 109, nr 46, s. 2082-2083Artikel i tidskrift (Övrigt vetenskapligt)
  • 24.
    Hahn, Robert
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för läkemedelsforskning. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och intensivvårdskliniken US.
    Bahlmann, Hans
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för läkemedelsforskning. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och intensivvårdskliniken US.
    Nilsson, Lena
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för läkemedelsforskning. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och intensivvårdskliniken US.
    Dehydration and fluid volume kinetics before major open abdominal surgery2014Ingår i: Acta Anaesthesiologica Scandinavica, ISSN 0001-5172, E-ISSN 1399-6576, Vol. 58, nr 10, s. 1258-1266Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Introduction: Assessment of dehydration in the preoperative setting is of potential clinical value. The present study uses urine analysis and plasma volume kinetics, which have both been validated against induced changes in body water in volunteers, to study the incidence and severity of dehydration before open abdominal surgery begins. Methods: Thirty patients (mean age 64 years) had their urine analysed before major elective open abdominal surgery for colour, specific weight, osmolality and creatinine. The results were scored and the mean taken to represent a dehydration index. Thereafter, the patients received an infusion of 5ml/kg of Ringers acetate intravenously for over 15min. Blood was sampled for 70min and the blood haemoglobin concentration used to estimate the plasma volume kinetics. Results: Distribution of fluid occurred more slowly (Pless than0.01) and the elimination half-life was twice as long (median 40min, not significant) in the 11 patients (37%) diagnosed to be moderately dehydrated as compared with euhydrated patients. The dehydration index indicated that the fluid deficit in these patients corresponded to 2.5% of the body weight, whereas the deficit in the others was 1%. In contrast, the 11 patients who later developed postoperative nausea and vomiting had a very short elimination half-life, only 9min (median, Pless than0.01). These patients were usually euhydrated but had microalbuminuria (Pless than0.03) and higher natriuresis (Pless than0.01). Conclusions: The degree of dehydration before major surgery was modest as evidenced both by urine sampling and volume kinetic analysis.

  • 25.
    Hahn, Robert
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US. Södertälje Hospital, Sweden.
    Bergek, Christian
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet.
    Gebäck, Tobias
    Chalmers University of Technology, Gothenburg, Sweden.
    Zdolsek, Joachim
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Interactions between the volume effects of hydroxyethyl starch 130/0.4 and Ringer´s acetate2013Ingår i: Critical Care, ISSN 1466-609X, Vol. 17, nr 3Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    INTRODUCTION:

    The turnover of Ringer´s solutions is greatly dependent on the physiological situation, such as the presence of dehydration or anaesthesia. The present study evaluates whether the kinetics is affected by previous infusion of colloid fluid.

    METHODS:

    Ten male volunteers with a mean age of 22 years underwent three infusion experiments, on separate days and in random order. The experiments included 10 mL/kg of 6% hydroxyethyl starch 130/0.4 (Voluven™), 20 mL/kg of Ringer's acetate, and a combination of both, where Ringer´s was administered 75 minutes after the starch infusion ended. The kinetics of the volume expansion was analysed by non-linear least- squares regression, based on urinary excretion and serial measurement of blood haemoglobin concentration for up to 420 minutes.

    RESULTS:

    The mean volume of distribution of the starch was 3.12 L which agreed well with the plasma volume (3.14 L) estimated by anthropometry. The volume expansion following the infusion of starch showed monoexponential elimination kinetics with a half-life of two hours. Two interaction effects were found when Ringer´s acetate was infused after the starch. First, there was a higher tendency for Ringer´s acetate to distribute to a peripheral compartment at the expense of the plasma volume expansion. The translocated amount of Ringer´s was 70% higher when HES had been infused earlier. Second, the elimination half-life of Ringer´s acetate was five times longer when administered after the starch (88 versus 497 minutes, P <0.02).

    CONCLUSIONS:

    Starch promoted peripheral accumulation of the later infused Ringer´s acetate solution and markedly prolonged the elimination half-life.

  • 26.
    Hahn, Robert G.
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Clinical Fluid Therapy in the Perioperative Setting2011Samlingsverk (redaktörskap) (Övrigt vetenskapligt)
    Abstract [en]

    Clinical Fluid Therapy in the Peri-Operative Setting brings together some of the world's leading clinical experts in fluid management to explain what you should know when providing infusion fluids to surgical and critical care patients. Current evidence-based knowledge, essential basic science and modern clinical practice are explained in 25 focused and authoritative chapters. Each chapter guides the reader in the use of fluid therapy in all aspects of peri-operative patient care. Guidance is given on the correct selection, quantity and composition of fluids required as a consequence of the underlying pathology and state of hydration of the patient, and the type and duration of surgery. Edited by Robert G. Hahn, a highly experienced clinician and award-winning researcher in fluid therapy, this is essential reading for all anaesthetists, intensivists and surgeons.

  • 27.
    Hahn, Robert G.
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Clinical pharmacology of infusion fluids2012Ingår i: Acta Medica Lituanica, ISSN 1392-0138, Vol. 19, nr 3, s. 210-212Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fluids are used for intravenous infusion during practically all surgeries, but several different compositions are available on the market.

    Crystalloid fluids comprise lactated or acetated Ringer solutions, normal saline, Plasma-Lyte, hypertonic saline, and glucose. They lack allergic properties but are prone to cause peripheral tissue oedema. Their turn­ over is governed by physiological factors such as dehydration and drug effects.

    Colloid fluids include hydroxyethyl starch, albumin, dextran, and gelatin. These fluids have various degrees of allergic properties and do not promote peripheral oedema. Their half-life is usually about hours. Factors increasing the turnover rate are poorly known but might include inflammatory states.

    Current debates include the widespread use of normal saline, which should be replaced by Ringer’s or Plasma-Lyte in most situations, and the kidney damage associated with the use of starch in septic patients. New studies show that hypertonic saline does not improve survival or neurological damage in prehospital care.

  • 28.
    Hahn, Robert G
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Fluid therapy in uncontrolled hemorrhage - what experimental models have taught us2013Ingår i: Acta Anaesthesiologica Scandinavica, ISSN 0001-5172, E-ISSN 1399-6576, Vol. 57, nr 1, s. 16-28Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Intravenous fluid is life-saving in hypovolemic shock, but fluid sometimes aggravates the bleeding. During the past 25 years, animal models have helped our understanding of the mechanisms involved in this unexpected effect. A key issue is that vasoconstriction is insufficient to arrest the bleeding when damage is made to a major blood vessel. ‘Uncontrolled hemorrhage’ is rather stopped by a blood clot formed at the outside surface of the vessel, and the immature clot is sensitive to mechanical and chemical interactions. The mortality increases if rebleeding occurs. In the aortic tear model in swine, hemorrhage volume and the mortality increase from effective restoration of the arterial pressure. The mortality vs. amount of fluid curve is U-shaped with higher mortality at either end. Without any fluid at all, irreversible shock causes death provided the hemorrhage is sufficiently large. Crystalloid fluid administered in a 3 : 1 proportion to the amount of lost blood initiates serious rebleeding. Hypertonic saline 7.5% in 6% dextran 70 (HSD) also provokes rebleeding resulting in higher mortality in the recommended dosage of 4 ml/kg. Uncontrolled hemorrhage models in rats, except for the ‘cut-tail’ model, confirm the results from swine. To avoid rebleeding, fluid programs should not aim to fully restore the arterial pressure, blood flow rates, or blood volume. For a hemorrhage of 1000 ml, computer simulations show that deliberate hypovolemia (−300 ml) would be achieved by infusing 600–750 ml crystalloid fluid over 20–30 min or 100 ml of HSD over 10–20 min in an adult male.

  • 29.
    Hahn, Robert G
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för läkemedelsforskning. Research Unit, Södertälje Hospital, Södertälje, Sweden.
    Homeopathy: meta-analyses of pooled clinical data.2013Ingår i: Forschende Komplementärmedizin, ISSN 1661-4119, E-ISSN 1661-4127, Vol. 20, nr 5, s. 376-381Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the first decade of the evidence-based era, which began in the mid-1990s, meta-analyses were used to scrutinize homeopathy for evidence of beneficial effects in medical conditions. In this review, meta-analyses including pooled data from placebo-controlled clinical trials of homeopathy and the aftermath in the form of debate articles were analyzed. In 1997 Klaus Linde and co-workers identified 89 clinical trials that showed an overall odds ratio of 2.45 in favor of homeopathy over placebo. There was a trend toward smaller benefit from studies of the highest quality, but the 10 trials with the highest Jadad score still showed homeopathy had a statistically significant effect. These results challenged academics to perform alternative analyses that, to demonstrate the lack of effect, relied on extensive exclusion of studies, often to the degree that conclusions were based on only 5-10% of the material, or on virtual data. The ultimate argument against homeopathy is the 'funnel plot' published by Aijing Shang's research group in 2005. However, the funnel plot is flawed when applied to a mixture of diseases, because studies with expected strong treatments effects are, for ethical reasons, powered lower than studies with expected weak or unclear treatment effects. To conclude that homeopathy lacks clinical effect, more than 90% of the available clinical trials had to be disregarded. Alternatively, flawed statistical methods had to be applied. Future meta-analyses should focus on the use of homeopathy in specific diseases or groups of diseases instead of pooling data from all clinical trials. © 2013 S. Karger GmbH, Freiburg.

  • 30.
    Hahn, Robert G
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för läkemedelsforskning. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och intensivvårdskliniken US. Research Unit, Södertälje Hospital, Sweden.
    Should anaesthetists stop infusing isotonic saline?2014Ingår i: British Journal of Anaesthesia, ISSN 0007-0912, E-ISSN 1471-6771, Vol. 112, nr 1, s. 4-6Artikel i tidskrift (Refereegranskat)
  • 31.
    Hahn, Robert G
    Östergötlands Läns Landsting, Anestesi- och operationscentrum, Anestesi- och intensivvårdskliniken VIN. Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård.
    Volume Kinetics for Infusion Fluids2010Ingår i: Anesthesiology, ISSN 0003-3022, E-ISSN 1528-1175, Vol. 113, nr 2, s. 470-481Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Volume kinetics is a method for analyzing and simulating the distribution and elimination of infusion fluids. Approximately 50 studies describe the disposition of 0.9% saline, acetated and lactated Ringer´s solution, based on repeated measurements of the hemoglobin concentration and (sometimes) the urinary excretion.

    The slow distribution to the peripheral compartment results in a 50-75% larger plasma dilution during an infusion of crystalloid fluid than would be expected if distribution had been immediate. A drop in the arterial pressure during induction of anesthesia reduces the rate of distribution even further.

    The renal clearance of the infused fluid during surgery is only 10-20% compared to conscious volunteers. Some of this temporary decrease can be attributed to the anesthesia and probably also to preoperative psychological stress and/or dehydration. 

    Crystalloid fluid might be allocated to “non-functional” fluid spaces where it is unavailable for excretion. This amounts to approximately 20-25% during minor (thyroid) surgery.

  • 32.
    Hahn, Robert G.
    et al.
    Södertälje Hospital, Sweden.
    Andrijauskas, Audrius
    Vilnius University, Lithuania.
    Drobin, Dan
    CLINTEC, Karolinska Institutet, Huddinge, Sweden.
    Svensén, Christer
    Karolinska Institutet, Södersjukhuset, Stockholm, Sweden.
    Ivaskevicius, Juozas
    Vilnius University, Lithuania.
    A volume loading test for the detection of hypovolemia and dehydration2008Ingår i: Medicina (Kaunas), ISSN 1010-660X, E-ISSN 1648-9144, Vol. 44, nr 12, s. 953-959Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    BACKGROUND AND OBJECTIVES: There is a need for simple method allowing detection of dehydration and hypovolemia. Based on a new theory of homeostatic blood states, we hypothesized that hemodilution following standardized crystalloid fluid bolus can be used to discriminate between baseline normohydration and dehydration, also normovolemia and hypovolemia.

    METHODS: Computer simulations based on previously published kinetic data were used to define the best time points for discrimination between baseline normohydration and dehydration, also normovolemia and hypovolemia. Hemodilution was compared at the proposed timing in 20 volunteers who received 40 infusions of Ringer's solution of 25 mL/kg during 30 minutes.

    RESULTS: Simulations indicated that preexisting hypovolemia could be best detected at the end of infusion, while dehydration 20-30 min later. In baseline hypovolemia, the peak reduction of hemoglobin concentration was 16.0% at the end of infusion, while it was only 11.8%, when participants were normovolemic (P<0.004). In baseline dehydration, the residual hemodilution was 8.6%, when measured 30 min after the end of infusion. It was only 3.1% in baseline normohydration (P<0.006).

    CONCLUSIONS: In response to fluid load, the baseline dehydration exaggerates the lowering of residual hemoglobin in respect to baseline. Meanwhile, baseline hypovolemia exaggerates the lowering of peak hemoglobin concentration. The volume loading test that deploys interpretation of hemoglobin dynamics in response to the test volume load could possibly serve as an easily available guide to indicate an individual patient's baseline hydration state and volemia. The introduction of continuous noninvasive monitoring of hemoglobin concentration would expand the applicability of the new method.

  • 33.
    Hahn, Robert G
    et al.
    Karolinska Institute, Stockholm, Sweden.
    Brauer, Lance
    University of Texas Medical Branch, Galveston, Texas, USA.
    Rodhe, Peter
    Karolinska Institute, Stockholm, Sweden.
    Svensén, Christer H
    University of Texas Medical Branch, Galveston, Texas, USA.
    Prough, Donald S
    University of Texas Medical Branch, Galveston, Texas, USA.
    Isoflurane inhibits compensatory intravascular volume expansion after hemorrhage in sheep2006Ingår i: Anesthesia and Analgesia, ISSN 0003-2999, E-ISSN 1526-7598, Vol. 103, nr 2, s. 350-358Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    After hemorrhage, blood volume is partially restored by transcapillary refill, a process of spontaneous compensatory intravascular volume expansion that we hypothesized would be inhibited by anesthesia. Six chronically instrumented sheep were subjected to four randomly ordered experiments while conscious or during anesthesia with isoflurane. After plasma volume measurement (indocyanine green), 15% or 45% of the blood volume was withdrawn. To quantify transcapillary refill, mass balance and kinetic calculations utilized repeated measurements of hemoglobin concentration, assuming that transcapillary refill would dilute hemoglobin concentration. After 15% hemorrhage, mean arterial blood pressure remained stable in both conscious and isoflurane-anesthetized sheep (normotensive hemorrhage) but decreased after 45% hemorrhage (hypotensive hemorrhage). After either normotensive or hypotensive hemorrhage, transcapillary refill occurred more rapidly during the first 40 min than during the next 140 min (P < 0.001). In conscious sheep, at 180 min, 57% and 42% of the bled volume had been restored after normotensive and hypotensive hemorrhage, respectively, in contrast to only 13% and 27% (P < 0.001) in isoflurane-anesthetized sheep. A novel kinetic model implicated hemodynamic factors in rapid, early transcapillary refill and decreased plasma oncotic pressure in subsequent slower filling. We conclude that isoflurane inhibits transcapillary refill after both normotensive and hypotensive hemorrhage in sheep.

  • 34.
    Hahn, Robert G.
    et al.
    South Hospital, Stockholm, Sweden.
    Fagerström, Tim
    South Hospital, Stockholm, Sweden.
    Tammela, Teuvo L. J.
    Tampere University Hospital, Finland.
    Van Vierssen Trip, Oncko
    Ziekenhuis Gelderse Vallei, Ede, the Netherlands.
    Beisland, Hans Olav
    Sorlandet Hospital, Arendal, Norway.
    Duggan, Annette
    GlaxoSmithKline, Greenford, UK.
    Morrill, Betsy
    GlaxoSmithKline, Research Triangle Park, North Carolina, USA.
    Blood loss and postoperative complications associated with transurethral resection of the prostate after pretreatment with dutasteride2007Ingår i: BJU International, ISSN 1464-4096, E-ISSN 1464-410X, Vol. 99, nr 3, s. 587-594Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    OBJECTIVE: To determine whether pretreatment with dutasteride, a dual 5alpha-reductase inhibitor (5ARI), reduces surgical blood loss or postoperative complications in patients with benign prostatic hyperplasia (BPH) who undergo transurethral resection of the prostate (TURP).

    PATIENTS AND METHODS: This double-blind, randomized, placebo-controlled, multicentre study comprised 214 patients with BPH. Placebo was compared with dutasteride 0.5 mg/day 2 weeks before and after TURP, or 4 weeks before and 2 weeks after TURP. Surgical blood loss was measured using a haemoglobin photometer (HemoCue AB, Angelholm, Sweden) and postoperative adverse events were recorded. Microvessel density (MVD) was calculated by immunostaining and light microscopy of the prostatic chips.

    RESULTS: Although dutasteride reduced serum dihydrotestosterone (DHT) by 86-89% in 2-4 weeks, and intraprostatic DHT was approximately 10 times lower than in the placebo group, the (adjusted) mean haemoglobin (Hb) loss during surgery was 2.15-2.55 g Hb/g resectate with no significant difference in blood loss between the groups either during or after TURP. Clot retention occurred in 6-11% and urinary incontinence in 14-15% of patients during the 14 weeks after TURP, with no difference between the groups. The MVD at TURP was also similar for all groups.

    CONCLUSION: There were no significant reductions in blood loss during or after TURP or complications afterward with dutasteride compared with placebo, despite significant suppression of intraprostatic DHT. Blood loss and transfusion rates in the placebo group were lower than those previously reported in studies where there was a beneficial effect of a 5ARI, relative to placebo, on bleeding during TURP.

  • 35.
    Hahn, Robert G
    et al.
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för läkemedelsforskning. Research Unit, Södertälje Hospital, Södertälje, Sweden.
    Ljunggren, Stefan
    Research Unit, Södertälje Hospital, Södertälje, Sweden.
    Preoperative insulin resistance reduces complications after hip replacement surgery in non-diabetic patients.2013Ingår i: BMC Anesthesiology, ISSN 1471-2253, E-ISSN 1471-2253, Vol. 13, nr 1, s. 39-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    BACKGROUND: Insulin resistance negatively affects the outcome of surgery in patients with type 2 diabetes. This association is often believed to be present in other patient populations as well, but studies are lacking on the influence of preoperative insulin resistance on the clinical course of surgery in non-diabetic patients.

    METHODS: Sixty non-diabetic patients with a mean age of 68 years underwent a 75-min intravenous glucose tolerance test (IVGTT) one day before and after elective hip replacement surgery. Patients were regarded to be either insulin resistant (< median insulin sensitivity) or not (> median insulin sensitivity). Hypotensive events occurring in the postoperative care unit and complications in the orthopedic ward were recorded. Fatigue and well-being were assessed via questionnaires.

    RESULTS: A total of 52 patients were included in the final analysis. Insulin resistance before surgery was associated with a lower risk of arterial hypotension in the postoperative care unit (systolic pressure < 80 mmHg; P < 0.05) and with fewer complications in the orthopedic ward (mean 1.9 versus 1.2 per operation, P < 0.01), particularly with respect to nausea/vomiting (P < 0.04) and arterial hypotension (P < 0.05). Fewer of these patients had more than one complication (23% versus 58%, P < 0.001), while no statistical link between preoperative insulin resistance and fatigue or well-being was evident. Insulin resistance, when measured one day postoperatively, did not correlate with the number of complications.

    CONCLUSIONS: Preoperative insulin resistance offers some benefit in the postoperative period and early convalescence in non-diabetic patients who undergo hip replacement surgery.

  • 36.
    Hahn, Robert G
    et al.
    Stockholm South Hospital, Sweden.
    Yin, Li
    Karolinska Institute, Stockholm, Sweden.
    Ekengren, Jan
    Nacka Hospital, Stockholm, Sweden.
    Sandfeldt, Lars
    Sabbatsberg Hospital, Stockholm, Sweden.
    Vascular endothelial growth factor in serum indicates cardiovascular risk in urology patients2006Ingår i: Scandinavian Journal of Urology and Nephrology, ISSN 0036-5599, E-ISSN 1651-2065, Vol. 40, nr 2, s. 144-148Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    OBJECTIVE: We hypothesized that a high serum concentration of vascular endothelial growth factor (VEGF), a cytokine involved in prostate growth which is also upregulated in chronic ischemia, indicates an increased risk of cardiovascular disease and death in urology patients.

    MATERIAL AND METHODS: The serum VEGF concentration was measured in 219 males (mean age 72 years) who sought medical attention because of lower urinary tract symptoms. Data on cardiovascular events and survival were obtained from the hospital registry of Stockholm County and the Death Registry over a period of up to 10 years (mean 6.2 years).

    RESULTS: After adjusting for the effects of age and smoking, patients with a serum VEGF level in the upper 20% of the cohort (>500 pg/ml) had an increased risk of developing cardiovascular disease (hazard ratio 2.18; 95% CI 1.04-4.60), including acute myocardial infarction (3.36; 1.35-8.41) and stroke (3.98; 1.61-9.86). They also had an increased risk of death (1.74; 1.01-3.00). These differences from patients with a lower serum VEGF concentration (<300 pg/ml) were manifested 2-5 years after the blood sample was taken.

    CONCLUSION: An elevated VEGF level in peripheral blood was a risk factor for subsequent development of cardiovascular disease.

  • 37.
    Hahn, Robert
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för läkemedelsforskning. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och intensivvårdskliniken US.
    Geback, Tobias
    Chalmers, Sweden .
    Fluid volume kinetics of dilutional hyponatremia; a shock syndrome revisited2014Ingår i: Clinics, ISSN 1807-5932, E-ISSN 1980-5322, Vol. 69, nr 2, s. 120-127Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    OBJECTIVE: To evaluate whether the pathophysiology of shock syndromes can be better understood by comparing central hemodynamics with kinetic data on fluid and electrolyte shifts. METHODS: We studied the dilutional hyponatremic shock that developed in response to overhydration with electrolyte-free irrigating fluid - the so-called transurethral resection syndrome - by comparing cardiac output, arterial pressures, and volume kinetic parameters in 17 pigs that were administered 150 ml/kg of either 1.5% glycine or 5% mannitol by intravenous infusion over 90 minutes. RESULTS: Natriuresis appeared to be the key factor promoting hypovolemic hypotension 15-20 minutes after fluid administration ended. Excessive sodium excretion, due to osmotic diuresis caused by the irrigant solutes, was associated with high estimates of the elimination rate constant (k(10)) and low or negative estimates of the rate constant describing re-distribution of fluid to the plasma after translocation to the interstitium (k(21)). These characteristics indicated a high urinary flow rate and the development of peripheral edema at the expense of plasma volume and were correlated with reductions in cardiac output. The same general effects of natriuresis were observed for both irrigating solutions, although the volume of infused 1.5% glycine had a higher tendency to enter the intracellular fluid space. CONCLUSION: Comparisons between hemodynamics and fluid turnover showed a likely sequence of events that led to hypovolemia despite intravenous administration of large amounts of fluid.

  • 38.
    Hahn, Robert
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Li, Yuhong
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet.
    Zdolsek, Joachim
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Hand- och plastikkirurgiska kliniken US. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Non-invasive monitoring of blood haemoglobin for analysis of fluid volume kinetics2010Ingår i: Acta Anaesthesiologica Scandinavica, ISSN 0001-5172, E-ISSN 1399-6576, Vol. 54, nr 10, s. 1233-1240Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background: A commercially available pulse oximeter that reports blood haemoglobin (Hb) concentration is evaluated. This study considers whether this device can provide serial Hb data that would be sufficiently reliable for volume kinetic analysis of infusion fluids.

    Methods: Forty infusions of 5 or 10 ml/kg of acetated Ringer's solution were given over 15 min in 10 healthy volunteers. Hb was measured on 17 different occasions over 120 min using the Radical 7 pulse oximeter and compared with the result of invasive blood sampling (control). A one-volume kinetic model was applied to each data series. The pulse oximeter also reported the perfusion index (PI).

    Results: The median deviation between the 680 invasive and non-invasive Hb samples (the accuracy) was 1.6% and the absolute median deviation (precision) was 4.6%. Between-subject factors explained half of the variation in the difference between non-invasive vs. invasive sampling.

    Ten of the 40 non-invasive series of Hb values were discarded from kinetic analysis due to poor quality. The remaining 30 series showed a smaller distribution volume for the infused fluid when kinetic analysis was based on the non-invasive method (3.0 vs. 5.3 l; P<0.001). This was due to co-variance with the PI, which exaggerated the decrease in Hb caused by the infusions. The non-invasive method might provide useful kinetic data at the group level, but individual curves deviated too much from the invasive data to be reliable.

    Conclusions: Non-invasive measurement of the Hb concentration during volume loading could not provide useful kinetic data for individuals.

  • 39.
    Hahn, Robert
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Lindahl, C C
    Karolinska University Hospital.
    Drobin, D
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Volume kinetics of acetated Ringer's solution during experimental spinal anaesthesia2011Ingår i: Acta Anaesthesiologica Scandinavica, ISSN 0001-5172, E-ISSN 1399-6576, Vol. 55, nr 8, s. 987-994Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background:

    General anaesthesia lowers the clearance of crystalloid fluid, but the volume kinetics of such fluid throughout the duration of spinal anaesthesia has not been studied.

    Methods:

    Ten female volunteers (mean age 29 years) received an intravenous infusion of 25 ml/kg of acetated Ringer's solution with and without spinal anaesthesia. A volume kinetic model was fitted to serial measurements of the haemoglobin concentration over 240 min based on arterial, cubital vein, and femoral vein blood. The measured urine flow was compared to the model-predicted elimination.

    Results:

    The arterial pressure remained stable, although the block reached to Th3-Th5 in half of the volunteers. There were no differences in fluid kinetics between the spinal anaesthesia and the control experiments. The administered volume was well confined to the kinetic system, which consisted of two communicating fluid spaces that were 2.8 l and approximately 7 l in size at baseline. The arteriovenous difference in plasma dilution remained positive for 30 min post-infusion in those having analgesia reaching to Th3-Th5, which differed significantly from low-level analgesia (Th12-L2, P < 0.03) when venous plasma was sampled from the leg. The urinary excretion averaged 1.13 l and 1.01 l for the spinal and control experiments, respectively. Volume kinetics predicted the urinary excretion at 5- to 10-min intervals with an overall bias of 52 ml.

    Conclusion:

    Acetated Ringer's solution showed the same kinetics during experimental spinal anaesthesia as when the fluid was infused alone. Hence, spinal anaesthesia is not associated with the reduced fluid clearance reported for general anaesthesia.

  • 40.
    Hahn, Robert
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Ljunggren, Stefan
    Södertalje Hospital.
    Larsen, Filip
    Karolinska Institute.
    Nystrom, Thomas
    Karolinska Institute.
    A simple intravenous glucose tolerance test for assessment of insulin sensitivity2011Ingår i: Theoretical Biology Medical Modelling, ISSN 1742-4682, E-ISSN 1742-4682, Vol. 8, nr 12Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background

    The aim of the study was to find a simple intravenous glucose tolerance test (IVGTT) that can be used to estimate insulin sensitivity.

    Methods

    In 20 healthy volunteers aged between 18 and 51 years (mean, 28) comparisons were made between kinetic parameters derived from a 12-sample, 75-min IVGTT and the Mbw (glucose uptake) obtained during a hyperinsulinemic euglycemic glucose clamp. Plasma glucose was used to calculate the volume of distribution (Vd) and the clearance (CL) of the injected glucose bolus. The plasma insulin response was quantified by the area under the curve (AUCins). Uptake of glucose during the clamp was corrected for body weight (Mbw).

    Results

    There was a 7-fold variation in Mbw. Algorithms based on the slope of the glucose-elimination curve (CL/Vd) in combination with AUCins obtained during the IVGTT showed statistically significant correlations with Mbw, the linearity being r2 = 0.63-0.83. The best algorithms were associated with a 25-75th prediction error ranging from -10% to +10%. Sampling could be shortened to 30-40 min without loss of linearity or precision.

    Conclusion

    Simple measures of glucose and insulin kinetics during an IVGTT can predict between 2/3 and 4/5 of the insulin sensitivity.

  • 41.
    Hahn, Robert
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för läkemedelsforskning. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Anestesi- och intensivvårdskliniken US.
    Lyons, Gordon
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för läkemedelsforskning. Linköpings universitet, Medicinska fakulteten.
    The half-life of infusion fluids An educational review2016Ingår i: European Journal of Anaesthesiology, ISSN 0265-0215, E-ISSN 1365-2346, Vol. 33, nr 7, s. 475-482Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    An understanding of the half-life (T-1/2) of infused fluids can help prevent iatrogenic problems such as volume overload and postoperative interstitial oedema. Simulations show that a prolongation of the T-1/2 for crystalloid fluid increases the plasma volume and promotes accumulation of fluid in the interstitial fluid space. The T-1/2 for crystalloids is usually 20 to 40 min in conscious humans but might extend to 80 min or longer in the presence of preoperative stress, dehydration, blood loss of amp;lt;1 l or pregnancy. The longest T-1/2 measured amounts to between 3 and 8 h and occurs during surgery and general anaesthesia with mechanical ventilation. This situation lasts as long as the anaesthesia. The mechanisms for the long T-1/2 are only partly understood, but involve adrenergic receptors and increased renin and aldosterone release. In contrast, the T-1/2 during the postoperative period is usually short, about 15 to 20 min, at least in response to new fluid. The commonly used colloid fluids have an intravascular persistence T-1/2 of 2 to 3 h, which is shortened by inflammation. The fact that the elimination T-1/2 of the infused macromolecules is 2 to 6 times longer shows that they also reside outside the bloodstream. With a colloid, fluid volume is eliminated in line with its intravascular persistence, but there is insufficient data to know if this is the same in the clinical setting.

  • 42.
    Hahn, Robert
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för läkemedelsforskning. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Anestesi- och intensivvårdskliniken US. Sodertalje Hospital, Sweden.
    Nyberg Isacson, M.
    Soder Sjukhuset, Sweden.
    Fagerstrom, T.
    Karolinska Institute, Sweden.
    Rosvall, J.
    Soder Sjukhuset, Sweden.
    Nyman, C. R.
    Soder Sjukhuset, Sweden.
    Isotonic saline in elderly men: an open-labelled controlled infusion study of electrolyte balance, urine flow and kidney function2016Ingår i: Anaesthesia, ISSN 0003-2409, E-ISSN 1365-2044, Vol. 71, nr 2, s. 155-162Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Isotonic saline is a widely-used infusion fluid, although the associated chloride load may cause metabolic acidosis and impair kidney function in young, healthy volunteers. We wished to examine whether these effects also occurred in the elderly, and conducted a crossover study in 13 men with a mean age of 73 years (range 66-84), who each received intravenous infusions of 1.5 l of Ringers acetate and of isotonic saline. Isotonic saline induced mild changes in plasma sodium (mean +1.5 mmol.l(-1)), plasma chloride (+3 mmol.l(-1)) and standard bicarbonate (-2 mmol.l(-1)). Three hours after starting the infusions, 68% of the Ringers acetate and 30% of the infused saline had been excreted (p &lt; 0.01). The glomerular filtration rate increased in response to both fluids, but more after the Ringers acetate (p &lt; 0.03). Pre-infusion fluid retention, as evidenced by high urinary osmolality (&gt; 700 mOsmol.kg(-1)) and/or creatinine (&gt; 7 mmol.l(-1)), was a strong factor governing the responses to both fluid loads.

  • 43.
    Hahn, Robert
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Nystrom, Thomas
    Karolinska Institute.
    Plasma Volume Expansion Resulting from Intravenous Glucose Tolerance Test2011Ingår i: Computational & Mathematical Methods in Medicine, ISSN 1748-670X, E-ISSN 1748-6718, Vol. 2011, nr 965075Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Objective. To quantify the degree of plasma volume expansion that occurs during an intravenous glucose tolerance test (IVGTT). Methods. Twenty healthy volunteers (mean age, 28 years) underwent IVGTTs in which 0.3 g/kg of glucose 30% was injected as a bolus over 1 min. Twelve blood samples were collected over 75 min. The plasma glucose and blood hemoglobin concentrations were used to calculate the volume distribution (𝑉𝑑) and the clearance (𝐶𝐿) of both the exogenous glucose and the injected fluid volume. Results. The IVGTT caused a virtually instant plasma volume expansion of 10%. The half-life of the glucose averaged 15 min and the plasma volume expansion 16 min. Correction of the fluid kinetic model for osmotic effects after injection reduced 𝐶𝐿 for the infused volume by 85%, which illustrates the strength of osmosis in allocating fluid back to the intracellular fluid space. Simulations indicated that plasma volume expansion can be reduced to 60% by increasing the injection time from 1 to 5 min and reducing the glucose load from 0.3 to 0.2 g/kg. Conclusion. A regular IVGTT induced an acute plasma volume expansion that peaked at 10% despite the fact that only 50–80 mL of fluid were administered.                                    

  • 44.
    Hahn, Robert
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för läkemedelsforskning. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Nyström, Thomas
    Karolinska Institute, Sweden.
    Ljunggren, Stefan
    Södertalje Hospital, Sweden.
    Plasma volume expansion from the intravenous glucose tolerance test before and after hip replacement surgery2013Ingår i: Theoretical Biology Medical Modelling, ISSN 1742-4682, E-ISSN 1742-4682, Vol. 10, nr 48Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background

    Hyperosmotic glucose is injected intravenously when an intravenous glucose tolerance test (IVGTT) is initiated. The extent and time period of plasma volume expansion that occurs in response to the glucose load has not been studied in the perioperative setting.

    Methods

    Twenty-two non-diabetic patients aged between 57 and 76 years (mean 68) underwent an IVGTT, during which 0.3 g/kg of glucose 30% (1 ml/kg) was injected as a bolus over one minute, one day before and two days after hip replacement surgery. Twelve blood samples were collected over 75 minutes from each patient. The turnover of both the exogenous glucose and the injected fluid volume was calculated by means of mass balance and volume kinetic analysis.

    Results

    The IVGTT raised plasma glucose by 9 mmol/L and the plasma volume by 8%. The extracellular fluid volume increased by 320 (SD 60) ml of which 2/3 could be accounted for in the plasma. The half-life of the exogenous glucose averaged 30 minutes before surgery and 36 minutes postoperatively (P < 0.02). The glucose elimination governed 86% of the decay of the plasma volume expansion, which occurred with a half-life of 12 minutes before to 21 minutes after the surgery (median, P < 0.001).

    Conclusion

    Hyperosmotic glucose translocated intracellular water to the plasma volume rather than to the entire extracellular fluid volume. The preferential re-distribution acts to dilute the plasma concentrations used to quantify insulin sensitivity and ß-cell function from an IVGTT. The greater-than-expected plasma dilution lasted longer after than before surgery.

  • 45.
    Hahn, Robert
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för läkemedelsforskning. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Waldréus, Nana
    Södertälje Hospital, Sweden .
    An Aggregate Urine Analysis Tool to Detect Acute Dehydration2013Ingår i: International Journal of Sport Nutrition & Exercise Metabolism, ISSN 1526-484X, E-ISSN 1543-2742, Vol. 23, nr 4, s. 303-311Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    PURPOSE:

    Urine sampling has previously been evaluated for detecting dehydration in young male athletes. The present study investigated whether urine analysis can serve as a measure of dehydration in men and women of a wide age span.

    METHODS:

    Urine sampling and body weight measurement were undertaken before and after recreational physical exercise (median time: 90 minutes) in 57 volunteers aged between 17 and 69 years (mean age: 42). Urine analysis included urine color, osmolality, specific gravity, and creatinine.

    RESULTS:

    The volunteers' body weight decreased 1.1% (mean) while they exercised. There were strong correlations between all four urinary markers of dehydration (r = 0.73 to 0.84, P < 0.001). Researchers constructed a composite dehydration index graded from 1 to 6 based on these markers. This index changed from 2.70 before exercising to 3.55 after exercising, which corresponded to dehydration of 1.0% as given by a preliminary reference curve based on seven previous studies in athletes. Men were slightly dehydrated at baseline (mean: 1.9%) compared to women (mean: 0.7%; P < 0.001), while age had no influence on the results. A final reference curve that considered both the present results and the seven previous studies was constructed in which exercise-induced weight loss (x) was predicted by the exponential equation x= 0.20 dehydration index.

    CONCLUSION:

    Urine sampling can be used to estimate weight loss due to dehydration in adults up to the age of 70 years. A robust dehydration index based on four indicators reduces the influence of confounders.

  • 46.
    Hedin, Annika
    et al.
    South Hospital, Stockholm, Sweden.
    Hahn, Robert G
    South Hospital, Stockholm, Sweden.
    Volume expansion and plasma protein clearance during intravenous infusion of 5% albumin and autologous plasma2005Ingår i: Clinical Science, ISSN 0143-5221, E-ISSN 1470-8736, Vol. 108, nr 3, s. 217-224Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Autologous plasma may be used to replace plasma volume and plasma proteins during surgery, but its effectiveness is largely unknown. In the present study, the characteristics of predonated frozen and thawed autologous plasma were compared with those of 5% albumin in 15 male volunteers who received 10 ml/kg of body weight of these colloids as intravenous infusions over 30 min. Venous blood was sampled and urine was collected over 8 h to outline the volume expansion and blood-interstitial fluid space transport of three plasma proteins (albumin, fibrinogen and antithrombin) by means of mass balance analysis. The maximum plasma dilution of 5% albumin and autologous plasma averaged 17 and 21% respectively, and their half-lives were 2.5 and 2.9 h respectively (P<0.03). The between-subject variability in dilution was most pronounced for autologous plasma. Transport of protein from blood to the interstitial space occurred faster when the infused fluid contained the protein in question. The rate was highest at 60 min, and the process was still in progress at 8 h when approx. 60% of the infused albumin, 45% of the fibrinogen and 75% of the infused antithrombin had been translocated to the interstitial fluid space. In contrast with the proteins, excess plasma water was removed by urinary excretion. It is concluded that the volume expansion is equivalent for the two colloid fluids, although it is more predictable for 5% albumin. The transport of protein outlasted the volume expansion.

  • 47.
    Heinius, Goran
    et al.
    Karolinska Institute.
    Hahn, Robert
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Sonden, Anders
    Karolinska Institute.
    HYPOTHERMIA INCREASES REBLEEDING DURING UNCONTROLLED HEMORRHAGE IN THE RAT2011Ingår i: Shock, ISSN 1073-2322, E-ISSN 1540-0514, Vol. 36, nr 1, s. 60-66Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Trauma registers show that hypothermia (HT) is an independent risk factor for death during hemorrhagic shock, although experimental animal studies indicate that HT may be beneficial during these conditions. However, the animal models were not designed to detect the expected increase in bleeding caused by HT. In a new model for uncontrolled bleeding, 40 Sprague-Dawley rats were exposed to a standardized femoral artery injury and randomized to either normothermia or HT. Ketamine/midazolam was used to minimize hemodynamic changes due to the anesthesia. The hypothermic rats were cooled to 30 degrees C and rewarmed again at 90 min. The study period was 3 h. The incidence, onset time, duration, and volume of bleedings as well as hemodynamic and metabolic changes were recorded. There was no difference between groups with respect to the initial bleeding. Rebleedings occurred among 60% of the animals in both groups. Hypothermic rebleeders had more, larger, and longer rebleedings, resulting in a total rebleeding volume amounting to 41% of their estimated blood volume. The corresponding figure for the normothermic rebleeders was 3% (P less than 0.001). Total rebleeding volume was significantly larger in the hypothermic group, even at body temperatures greater than 35 degrees C. We conclude that the risk of rebleeding from a femoral injury is greater in the presence of cooling and HT. The larger rebleeding volumes seen even at body temperatures greater than 35 degrees C indicate that factors other than temperature-induced coagulopathy also contributed to the increased hemorrhage.

  • 48.
    Heinius, Göran
    et al.
    Section of Surgery, Department of Clinical Science and Education, Karolinska Institutet, Stockholm, Sweden.
    Sondén, Anders
    Section of Surgery, Department of Clinical Science and Education, Karolinska Institutet, Stockholm, Sweden.
    Hahn, Robert G
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Effects of Different Fluid Regimes and Desmopressin on Uncontrolled Hemorrhage During Hypothermia in the Rat2012Ingår i: Therapeutic Hypothermia and Temperature Management, ISSN 2153-7658, E-ISSN 2153-7933, Vol. 2, nr 2, s. 53-60Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Resuscitation with large volumes of crystalloids during traumatic hemorrhagic shock might increase the mortality by inducing rebleeding. However, few studies have addressed this problem during hypothermic conditions. Sixty-eight Sprague-Dawley rats were exposed to a standardized femoral artery injury and resuscitated with low (LRe), medium (MRe), or high (HRe) intensity using lactated Ringer's solution after being cooled to 30°C. An additional MRe group was also given desmopressin since this drug might reverse hypothermic-induced impairment of the primary hemostasis. The rats were rewarmed after 90 minutes and observed for 3 hours. The incidence, on-set time, duration, and volume of bleedings and hemodynamic changes were recorded. Rebleedings occurred in 60% of all animals and were more voluminous in the HRe group than in the LRe group (p=0.01). The total rebleeding volume per animal increased with the rate of fluid administration (r=0.50, p=0.01) and the duration of each rebleeding episode was longer in the HRe group than in the LRe group (p<0.001). However, the mortality tended to be higher in the LRe group (LRe=6/15, MRe=1/15, HRe=2/15, p=0.07). Desmopressin did not change the bled volume or the mortality. Overall, the mortality increased if rebleeding occurred (10/35 rebleeders died vs. 1/25 nonrebleeders, p=0.015). Liberal fluid administration increased the rebleeding volume while a trend toward higher mortality was seen with the restrictive fluid program. Desmopressin had no effect on the studied parameters.

  • 49.
    Holte, Kathrine
    et al.
    Hvidovre University Hospital, Denmark.
    Hahn, Robert G
    South Hospital, Stockholm, Sweden.
    Ravn, Lisbet
    Hvidovre University Hospital, Denmark.
    Bertelsen, Kasper G
    Hvidovre University Hospital, Denmark.
    Hansen, Stinus
    Hvidovre University Hospital, Denmark.
    Kehlet, Henrik
    Rigshospitalet, Denmark.
    Influence of "liberal" versus "restrictive" intraoperative fluid administration on elimination of a postoperative fluid load2007Ingår i: Anesthesiology, ISSN 0003-3022, E-ISSN 1528-1175, Vol. 106, nr 1, s. 75-79Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    BACKGROUND: Previously, the authors found "liberal" fluid administration (approximately 3 l Ringer's lactate [RL]) to improve early rehabilitation after laparoscopic cholecystectomy, suggesting functional hypovolemia to be present in patients receiving "restrictive" fluid administration (approximately 1 l RL). Because volume kinetic analysis after a volume load may distinguish between hypovolemic versus normovolemic states, the authors applied volume kinetic analysis after laparoscopic cholecystectomy to explain the difference in outcome between 3 and 1 l RL.

    METHODS: In a prospective, nonrandomized trial, the authors studied 20 patients undergoing laparoscopic cholecystectomy. Ten patients received 15 ml/kg RL (group 1) and 10 patients received 40 ml/kg RL (group 2) intraoperatively. All other aspects of perioperative management were standardized. A 12.5-ml/kg RL volume load was infused preoperatively and 4 h postoperatively. The distribution and elimination of the fluid load was estimated using volume kinetic analysis.

    RESULTS: Patient baseline demographics and intraoperative data did not differ between groups, except for intraoperative RL, having a median of 1,118 ml (range, 900-1,400 ml) in group 1 compared with a median of 2,960 ml (range, 2,000-3,960 ml) in group 2 (P<0.01). There were no significant preoperative versus postoperative differences in the size of the body fluid space expanded by infused fluid (V), whereas the clearance constant kr was higher postoperatively versus preoperatively (P=0.03). The preoperative versus postoperative changes in volume kinetics including V were not different between the two groups.

    CONCLUSIONS: Elimination of an intravenous fluid load was increased after laparoscopic cholecystectomy per se but not influenced by the amount of intraoperative fluid administration.

  • 50.
    Hong Li, Yu
    et al.
    Zhejiang University, China.
    Bin Zhu, Hai
    Zhejiang University, China.
    Zheng, Xiaozhu
    Zhejiang Hospital, China.
    Jian Chen, Han
    Zhejiang University, China.
    Shao, Liang
    Yuhuan County Peoples Hospital, China.
    Hahn, Robert G
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Low doses of esmolol and phenylephrine act as diuretics during intravenous anesthesia2012Ingår i: Critical Care, ISSN 1364-8535, E-ISSN 1466-609X, Vol. 16, nr 1Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Introduction

    The renal clearance of infused crystalloid fluid is very low during anaesthesia and surgery, but experiments in conscious sheep indicate that the renal fluid clearance might approach a normal rate when the adrenergic balance is modified.

    Methods

    Sixty females (mean age, 32 years) undergoing laparoscopic gynecological surgery were randomized to control group and received only the conventional anesthetic drugs and 20 ml/kg of lactated Ringer's over 30 mins. The others were also given an infusion of 50 μg/kg/min of esmolol (beta1-receptor blocker) or 0.01 μg/kg/min of phenylephrine (alpha1-adrenergic agonist) over 3 hours. The distribution and elimination of infused fluid were studied by volume kinetic analysis based on urinary excretion and blood hemoglobin level.

    Results

    Both drugs significantly increased urinary excretion while heart rate and arterial pressure remained largely unaffected. The urine flows during non-surgery were 43, 147, and 176 ml in the control, esmolol, and phenylephrine groups, respectively (medians, P < 0.03). When surgery had started the corresponding values were 34, 65 and 61 ml (P < 0.04). At 3 hours, averages of 9%, 20%, and 25% of the infused volume had been excreted in the three groups (P < 0.01). The kinetic analyses indicated that both treatments slowed down the distribution of fluid from the plasma to the interstitial fluid space, thereby preventing hypovolemia.

    Conclusions

    Esmolol doubled and phenylephrine almost tripled urinary excretion during anesthesia-induced depression of renal fluid clearance.

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