Objectives: Cerebral complications continue to be a major cause of morbidity after cardiac surgery. Earlier studies have mainly focused on intraoperative events, but symptoms may also occur later in the postoperative period. The purpose of this study was to determine the incidence and risk factors of focal neurologic complications and timing of cerebral symptoms.

Design: A retrospective study.

Setting: Linköping University Hospital.

Participants: Two thousand four hundred eighty patients who underwent cardiac surgery from 1992 to 1995.

Interventions: Standard cardiopulmonary bypass (CPB) technique was used in all patients. Anticoagulant treatment included heparin and patients with coronary artery surgery were also administered acetylsalicylic acid and valve-surgery patients received warfarin or dicumarol.

Measurements and Main Results: Seventy-five patients (3%) had focal neurologic deficits and/or confusion postoperatively. In 32 patients (43%), the onset was not intraoperative but occurred later in the postoperative period. The lowest incidence of cerebral complications was found in patients who underwent single-valve replacement (1.2%) and the highest incidence was found in patients who underwent combined procedures (valve and coronary artery surgery; 7.6%). Patients greater than 70 years of age had a complication rate of 4.1% compared with 2.5% in patients aged 70 years and less (p < 0.05). The incidence of diabetes mellitus was 11.4% in the entire series, but was more common (18.7%; p < 0.05) in patients with cerebral symptoms. Also, 5.9% of all patients had a history of cerebrovascular disease compared with 14.7% (p < 0.01) of patients with cerebral complications.

Conclusion: Cerebral complications may be delayed after cardiac surgery, suggesting causes of cerebral damage other than intraoperative events. Valve-surgery patients had the lowest incidence and patients with combined procedures had the highest incidence of cerebral complications. Advanced age, diabetes mellitus, and preexisting cerebrovascular disease increased the risk.

Aims of the study: 1. to compare ropivacaine, a new long-acting amino-amide local anaesthetic drug, and bupivacaine (with/without adrenaline) concerning dermal analgesia and local vascular effects, 2. to design a suitable test procedure to evaluate changes in skin blood flow after intradermal injection of local anaesthetics, 3. to evaluate changes in skin blood flow of various concentrations of ropivacaine with/without adrenaline, 4. to investigate the influence of ropivacaine, bupivacaine, lidocaine, mepivacaine and prilocaine on the production of oxygen metabolites in human polymorphonuclear leukocytes (PMNL) (intra- and extracellular reactions), and 5. to examine the neural blocking characteristics on sensory, motor and sympathetic pathways using ropivacaine for epidural analgesia.

72 male patients scheduled for transurethral surgery and 50 male volunteers participated in this work. Heparinized blood was obtained from a total of 29 healthy adult blood donors.

Dermal analgesia was evaluated by pin-prick, skin colour changes by visual inspection, skin blood flow by laser Doppler flowmetry, sensory blockade by pin-prick, motor blockade by a modified Bromage scale, sympathetic blockade by assessments of skin resistance level (SRL) and response (SRR), skin temperature and skin blood flow (laser Doppler flowmetry). Production of oxygen metabolites by PMNLs was measured by luminal-enhanced chemiluminescence (intra- and extracellular reactions).

Ropivacaine produced significantly longer duration of dermal analgesia, following intradermal injection (0.1 ml, 30-G needle), compared with bupivacaine, in comparable concentrations. Addition of adrenaline increased the duration of both local anaesthetics. Local blanching was more frequent for plain solutions of ropivacaine.

The effect of drugs on local circulation may well be studied by intradennal injection (0.1 ml, 30-G needle, volar surface, forearms) and recording of changes in skin blood flow (laser Doppler flowmetry). The intradennal injection of a local anaesthetic drug may produce not only a further increase but also a decrease in skin blood flow, if the effect of an intradermal saline injection, causing a very reproducible flow increase, is considered in the evaluation of the net circulatory effect of the tested drug.

Intradermal injection of lidocaine 1% and bupivacaine 0.75% produced an increase in skin blood flow. Ropivacaine 1% produced a flow similar to saline, while a decrease was seen for ropivacaine 0.75%. Ropivacaine0.5%, 0.375%, 0.25%, 0.125% and 0.063% showed a gradual further reduction in flow, where 0.063% produced a flow similar to adrenaline-injection (5 Jlg/ml) and almost as low as at the untreated control sites. The combination of ropivacaine 1%, 0.5% , 0.25% and adrenaline did not accentuate but instead decreased the vasoconstrictive effect of adrenaline.

By and large a decrease in response of chemiluminescence for PMNLs was seen with the higher concentrations of the various local anaesthetics. Lidocaine showed a minor decrease even at lower concentrations. Ropivacaine 1000 J.Lg/ml showed a depression of both intra- and extracellular responses that was similar to, and even somewhat more pronounced than lidocaine 1000 J.Lg/ml. This effect could be of great interest e.g. for local antiinflammatory effects by topical administration, but it has to be further investigated. A marked increase for prilocaine (1000 Jlg/ml) in intracellular response accompanied with a reduction in extracellular response was noted.

Ropivacaine (0.5%, 0.75% with/without adrenaline) 20 ml administered epidurally provided a good sensory blockade and a motor blockade satisfactory for transurethral surgery. The maximum sensory level of analgesia was high, median Th 2-3. The majority of patients had a marked or complete sympathetic blockade in the lower limbs. Besides mild or moderate hypotension, which responded well to treatment with ephedrine, no other serious adverse reactions were seen, Addition of adrenaline did not provide any significant prolongation of the epidural blockade, and did not alter the influence upon the sympathetic blockade nor the hemodynamic changes during onset.

Background. Complications of an inadequate haemodynamic state are a leading cause of morbidity and mortality after cardiac surgery. Unfortunately, commonly used methods to assess haemodynamic status are not well documented with respect to outcome. The aim of this study was to investigate SV(O2) as a prognostic marker for short-and long-term outcome in a large unselected coronary artery bypass grafting (CABG) cohort and in subgroups with or without treatment for intraoperative heart failure. less thanbrgreater than less thanbrgreater thanMethods. Two thousand seven hundred and fifty-five consecutive CABG patients and subgroups comprising 344 patients with and 2411 patients without intraoperative heart failure, respectively, were investigated. SV(O2) was routinely measured on admission to the intensive care unit (ICU). The mean (SD) follow-up was 10.2 (1.5) yr. less thanbrgreater than less thanbrgreater thanResults. The best cut-off for 30 day mortality related to heart failure based on receiver-operating characteristic analysis was SV(O2) 60.1%. Patients with SV(O2) andlt;60% had higher 30 day mortality (5.4% vs 1.0%; P andlt; 0.0001) and lower 5 yr survival (81.4% vs 90.5%; P andlt; 0.0001). The incidences of perioperative myocardial infarction, renal failure, and stroke were also significantly higher, leading to a longer ICU stay. Similar prognostic information was obtained in the subgroups that were admitted to ICU with or without treatment for intraoperative heart failure. In patients admitted to ICU without treatment for intraoperative heart failure and SV(O2) andgt;= 60%, 30 day mortality was 0.5% and 5 yr survival 92.1%. less thanbrgreater than less thanbrgreater thanConclusions. SV(O2) andlt;60% on admission to ICU was related to worse short- and long-term outcome after CABG, regardless of whether the patients were admitted to ICU with or without treatment for intraoperative heart failure.

The first aim of this thesis was to evaluate a new minimally invasive axial blood flow pump for treatment of patients needing circulatory support after open heart surgery. This system, the Hemopump temporary cardiac assist device, is a very small catheter mounted intracorporeal pump, which is introduced transvalvularly into the left ventricle. The pump can be inserted either through the femoral artery or directly through a graft sutured to the ascending aorta. In an experimental model, the flow capacity of three different designs of the system was investigated. Flow capacity varied between 2.0 and 4.5 liters per minute, depending on the working conditions for the different pump models. Twenty,four patients were treated for post,cardiotomy heart failure. Fourteen patients (58 %) were weaned from the device and later discharged from the hospital. In a subgroup of these patients (54%) where early intervention was instituted, the survival rate was 85%. The pump proved to be an effective tool for unloading a failing left ventricle with preservation of multi-organ perfusion. A clinical protocol was established for postoperative management. The Hemopump was easy to adapt to the clinical setting, and device~ related complications were few.

The second aim was to develop a new less invasive procedure for CABG, avoiding the need for cardio~pulmonary bypass during these procedures. First an animal trial was performed as a feasibility study. In combination with the administration of a short~acting ~~blocker, esmolol, this method enabled precise coronary bypass surgery. When results became consistent a small pilot study was done on five patients showing that this was a reproducible technique. Finally a prospective randomized trial comparing this technique with conventional bypass surgery was carried out. The Hemopump supported bypass surgery did not prolong the procedure, did not require a longer time on circulatory support and bleeding was less. Postoperative enzyme levels indicated that ischemic insult to the myocardium was less than with conventional surgery.

In summary, this minimally invasive axial blood flow pump proved to be a powerful left ventricular assist system enabling a less invasive approach during conditions where circulatory support is needed.

Context The Modified Early Warning Score is a validated assessment tool for detecting risk of deterioration in patients at risk on medical and surgical wards. less thanbrgreater than less thanbrgreater thanObjective To assess the prognostic ability of the Modified Early Warning Score in predicting outcome after critical care. less thanbrgreater than less thanbrgreater thanDesign A prospective observational study. less thanbrgreater than less thanbrgreater thanSetting A tertiary care general ICU. less thanbrgreater than less thanbrgreater thanPatients Five hundred and eighteen patients aged at least 16 years admitted to the ICU at Linkoping University Hospital were included. less thanbrgreater than less thanbrgreater thanIntervention The Modified Early Warning Score was documented on arrival at the ICU and every hour for as long as the patient was breathing spontaneously, until discharge from the ICU. less thanbrgreater than less thanbrgreater thanMain outcome measures The primary endpoint was mortality in the ICU. Secondary endpoints were 30-day mortality, length of stay and readmission to the ICU. less thanbrgreater than less thanbrgreater thanResults Patients with a Modified Early Warning Score of at least six had significantly higher mortality in the ICU than those with a Modified Early Warning Score andlt;6 (24 vs. 3.4%, Pandlt; 0.001). A Modified Early Warning Score of at least six was an independent predictor of mortality in the ICU [odds ratio (OR) 5.5, 95% confidence interval (CI) 2.4-20.6]. The prognostic ability of the Modified Early Warning Score on admission to the ICU [area under the curve (AUC) 0.80, 95% CI 0.72-0.88] approached those of the Simplified Acute Physiology Score III (AUC 0.89, 95% CI 0.83-0.94) and the Sequential Organ Failure Assessment score on admission (AUC 0.91, 95% CI 0.86-0.97). A Modified Early Warning Score of at least six on admission was also an independent predictor of 30-day mortality (OR 4.3, 95% CI 2.3-8.1) and length of stay in the ICU (OR 2.3, 95% CI 1.4-3.8). In contrast, the Modified Early Warning Score on discharge from the ICU did not predict the need for readmission. less thanbrgreater than less thanbrgreater thanConclusion This study shows that the Modified Early Warning Score is a useful predictor of mortality in the ICU, 30-day mortality and length of stay in the ICU.

For direct visualization of myocardial ischemia during cardiac surgery, we tested the feasibility of presenting infrared (IR) tissue temperature maps in situ during surgery. A new augmented reality (AR) system, consisting of an IR camera and an integrated projector having identical optical axes, was used, with a high resolution IR camera as control. The hearts of five pigs were exposed and an elastic band placed around the middle of the left anterior descending coronary artery to induce ischemia. A proximally placed ultrasound Doppler probe confirmed reduction of flow. Two periods of complete ischemia and reperfusion were studied in each heart. There was a significant decrease in IR-measured temperature distal to the occlusion, with subsequent return to baseline temperatures after reperfusion (baseline 36.9 ± 0.60 (mean ± SD) versus ischemia 34.1 ± 1.66 versus reperfusion 37.4 ± 0.48; p < 0.001), with no differences occurring in the non-occluded area. The AR presentation was clear and dynamic without delay, visualizing the temperature changes produced by manipulation of the coronary blood flow, and showed concentrically arranged penumbra zones during ischemia. Surface myocardial temperature changes could be assessed quantitatively and visualized in situ during ischemia and subsequent reperfusion. This method shows potential as a rapid and simple way of following myocardial perfusion during cardiac surgery. The dynamics in the penumbra zone could potentially be used for visualizing the effect of therapy on intraoperative ischemia during cardiac surgery.

Thromboembolism (valve thrombosis and systemic embolism) is the main drawback of mechanical heart valve prostheses. The patients carrying these valves have to be subjected to life-long anticoagulant therapy to reduce thromboembolism. This therapy does not completely prevent these complications and may, if not properly controlled, even lead to life-threatening bleeding problems. Hemocompatibility of a mechanical heart valve is related to its engineering design and the construction material. To improve hemocompatibility of a mechanical heart valve, not only design but also valve material must be improved. Therefore the search for new materials or surface coatings that are more hemocompatible than those currently used must continue. The purpose of the present investigation was to develop an in vivo method, and to evaluate and compare hemocompatibility of some materials currently used, and for potential use, in ·prosthetic heart valves. Pyrolytic carbon (PyC), titanium (Ti), cobalt-chromium (CC), glutaraldehyde-treated bovine pericardium (Pe) and some new materials such as titanium nitride (TiN) and diamond-like carbon (DLC) were evaluated in three series of sheep experiments. The test materials were implanted in the central veins in the first and second series, and in the descending aorta in the third series. Up to four different materials could be tested simultaneously in each animal. No anticoagulant was given. After two hours of exposure to flowing blood, the test surfaces were explanted and prepared for photography and scanning electron microscopy (SEM). Thrombus area (the area covered by thrombus) was measured on close-up photographs of each surface using planimetry. Blood cell adhesion and blood-surface interaction were observed with SEM. The results showed more thrombi on PyC and Pe than on Ti and TiN. Leukocytes were the main type of blood cells adhering to PyC and DLC, and erythrocytes to Ti and TiN. Different materials exhibited different patterns of blood-surface interaction. Thrombus composition was largely related to the pattern of cell adhesion, indicating that the mechanism of early thrombus formation might be different on different surfaces. The results suggested that the method is practical and reliable. Under the present conditions PyC was not as hemocompatible as the metals currently used. TiN was more hemocompatible than PyC. Due to its combination of excellent hemocompatibility and wear resistance, TiN may be a promising new surface coating material for metallic components of mechanical heart valves, blood pumps and other devices in contact with blood.