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Respiratory monitoring using reflection mode photoplethysmography: clinical and physiological aspects
Linköping University, Department of Medical and Health Sciences, Anesthesiology. Linköping University, Faculty of Health Sciences.
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Photoplethysmography (PPG) is a non-invasive optical technique for monitoring variations in blood volume and blood flow in skin and other tissues. Light from a light-emitting diode is absorbed, scattered and reflected from the skin, and detected by a photodetector as a plethysmogram. The plethysmogram contains variations of different frequencies. The most clinically utilised is the pulse synchronous variation in the PPG application pulse oximetry, but there is also a respiratory rate synchronous variation (PPGt).

The aims of this work were to evaluate PPG as a clinical method for detection of breaths during anaesthesia, postoperative and intensive care, and to investigate possible circulatory factors in the physiological background of the respiratory synchronous part of the reflection mode PPG signal.

It was concluded that respiratory variations in reflection mode PPG derived from the forearm could be detected with high sensitivity and specificity. PPG, was not significantly affected by awake or anaesthetised state, though indirect signs of reduced sympathetic tone in the anaesthetic state were present, or by spontaneous or positive pressure ventilation. There were no significant differences between men and women or between young and old subjects. Circulatory pressure variations in phase with respiration were present on both the arterial and venous side and they showed the same degree of variation, as did PPG when provoking respiration. Squared coherence, cross-correlation and visual techniques for evaluating time differences were equally good.

Respiratory monitoring in the clinical setting is challenging and no golden standard exists. Methods based on airflow are mostly considered advantageous in detecting apnoea, but are less well tolerated by patients. The results indicate that PPG has a potential as a tool for monitoring respiratory rate. It is non-invasive, well tolerated and can be used for continuous monitoring.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet , 2005. , 70 p.
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 898
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:liu:diva-31535Local ID: 17335ISBN: 91-8529-905-7 (print)OAI: oai:DiVA.org:liu-31535DiVA: diva2:252358
Public defence
2005-05-26, Elsa Brändström-salen, Universitetssjukhuset, Linköping, 12:00 (Swedish)
Opponent
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2012-09-27Bibliographically approved
List of papers
1. Monitoring of respiratory rate in postoperative care using a new photoplethysmographic technique
Open this publication in new window or tab >>Monitoring of respiratory rate in postoperative care using a new photoplethysmographic technique
2000 (English)In: Journal of clinical monitoring and computing, ISSN 1387-1307, E-ISSN 1573-2614, Vol. 16, no 4, 309-315 p.Article in journal (Refereed) Published
Abstract [en]

Objective.Photoplethysmography (PPG) is a non-invasive optical technique that measures variations in skin blood volume and perfusion. The PPG signal contains components that are synchronous with respiratory and cardiacrhythms. We undertook this study to evaluate PPG for monitoring patients' respiratory rate in the postoperative care unit, using a new prototype device. We compared it with the established technique, transthoracic impedance (TTI).

Methods.PPG signals from 16 patients(ASA classes 1–2, mean age 43 years) who were recovering from general anaesthesia after routine operations were recorded continuously for 60minutes/patient. The respiratory synchronous part of the PPG signal was extracted by using a band pass filter. Detection of breaths in the filtered PPG signals was done both visually and by using an automated algorithm. In both procedures, the detected breaths were compared with the breaths detected in the TTI reference.

Results.A total of 10.661 breaths were recorded, and the mean ± SD respiratory rate was 12.3 ± 3.5breaths/minute. When compared with TTI, the rates of false positive and false negative breaths detected by PPG (visual procedure) were 4.6 ±4.5% and 5.8 ± 6.5%, respectively. When using the algorithm for breath detection from PPG, the rates of false positive andfalse negative breaths were 11.1 ± 9.7% and 3.7 ±3.8%, respectively, when compared to TTI. Lower respiratory rates increased the occurrence of false-positive breaths that were detected by the PPG using visual identification (p< 0.05). The same tendency was seen with the automated PPG procedure (p< 0.10).

Conclusions.Our results indicate that PPG has the potential to be useful for monitoring respiratory rate in the postoperative period.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-26704 (URN)10.1023/A:1011424732717 (DOI)11296 (Local ID)11296 (Archive number)11296 (OAI)
Available from: 2009-10-08 Created: 2009-10-08 Last updated: 2017-12-13Bibliographically approved
2. Respiratory variations in the reflection mode photoplethysmographic signal: relationships to peripheral venous pressure
Open this publication in new window or tab >>Respiratory variations in the reflection mode photoplethysmographic signal: relationships to peripheral venous pressure
2003 (English)In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 41, no 3, 249-254 p.Article in journal (Refereed) Published
Abstract [en]

Photoplethysmography (PPG) is a non-invasive optical way of measuring variations in blood volume and perfusion in the tissue, used in pulse oximetry for instance. Respiratory-induced intensity variations (RIIVs) in the PPG signal exist, but the physiological background is not fully understood. Respiration causes variations in the blood volume in the peripheral vascular bed. It was hypothesised that the filling of peripheral veins is one of the important factors involved. In 16 healthy subjects, the respiratory synchronous variations from a PPG reflection mode signal and the peripheral venous pressure (PVP) were recorded. Variations of tidal volume, respiratory rate and contribution from abdominal and thoracic muscles gave significant and similar amplitude changes in both RIIV and the respiratory variation of PVP (p<0.01). The highest amplitudes of both signals were found at the largest tidal volume, lowest respiratory rate and during mainly thoracic breathing, respectively. The coherence between PVP and RIIV signals was high, the median (quartile range) being 0.78 (0.42). Phase analysis showed that RIIV was usually leading PVP, but variations between subjects were large. Although respiratory-induced variations in PVP and PPG showed a close correlation in amplitude variation, a causal relationship between the signals could not be demonstrated.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-26703 (URN)10.1007/BF02348428 (DOI)11295 (Local ID)11295 (Archive number)11295 (OAI)
Available from: 2009-10-08 Created: 2009-10-08 Last updated: 2017-12-13Bibliographically approved
3. Macrocirculation is not the sole determinant of respiratory induced variations in the reflection mode photoplethysmographic signal
Open this publication in new window or tab >>Macrocirculation is not the sole determinant of respiratory induced variations in the reflection mode photoplethysmographic signal
2003 (English)In: Physiological Measurement, ISSN 0967-3334, E-ISSN 1361-6579, Vol. 24, no 4, 925-937 p.Article in journal (Refereed) Published
Abstract [en]

Photoplethysmography (PPG) is a non-invasive optical technique sensitive to variations in blood volume and perfusion in the tissue. Reflection mode PPG may have clinical advantages over transmission mode PPG. To improve clinical usefulness and further development of the reflection mode PPG, studies on factors that modify the signal are warranted. We studied the coherence between the respiratory induced intensity variations (RIIV) of the PPG signal and respiratory synchronous pressure variations in central venous pressure (CVP), peripheral venous pressure (PVP) and arterial blood pressure (ABP) during positive pressure ventilation on 12 patients under anaesthesia and on 12 patients with spontaneous breathing. During positive pressure ventilation the coherence between all signals was high. Inspiration was followed first by an increase in CVP, then by increases in ABP and PVP and lastly by RIIV indicating less back-scattered light. In spontaneously breathing patients the coherence was high, but the phases between the signals were changed. During inspiration, ABP decreased slightly before CVP, followed by a decrease in RIIV and PVP. The phase relation between RIIV and respiratory induced variation in macrocirculation changed with ventilatory mode, but not in a uniform way, indicating the influence of mechanisms other than macrocirculation involved in generating the RIIV signal.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-26705 (URN)10.1088/0967-3334/24/4/009 (DOI)11297 (Local ID)11297 (Archive number)11297 (OAI)
Available from: 2009-10-08 Created: 2009-10-08 Last updated: 2017-12-13Bibliographically approved
4. Respiration can be monitored by photoplethysmography with high sensitivity and specificity regardless of anaesthesia and ventilatory mode
Open this publication in new window or tab >>Respiration can be monitored by photoplethysmography with high sensitivity and specificity regardless of anaesthesia and ventilatory mode
2005 (English)In: Acta Anaesthesiologica Scandinavica, ISSN 0001-5172, E-ISSN 1399-6576, Vol. 49, no 8, 1157-1162 p.Article in journal (Refereed) Published
Abstract [en]

Background:  Photoplethysmography (PPG) is a non-invasive optical technique used, for instance, in pulse oximetry. Beside the pulse synchronous component, PPG has a respiratory synchronous variation (PPGr). Efforts have been made to utilize this component for indirect monitoring of respiratory rate and volume. Assessment of the clinical usefulness as well as of the physiological background of PPGr is required. We evaluated if anaesthesia and positive-pressure ventilation would affect PPGr.

Methods:  We recorded reflection mode PPGr, at the forearm, and the respiratory synchronous changes in central venous pressure (CVP), peripheral venous pressure (PVP) and arterial blood pressure (ABP) in 12 patients. Recordings for each patient were made on three occasions: awake with spontaneous breathing; anaesthetized with spontaneous breathing; and anaesthetized with positive-pressure ventilation. We analyzed the sensitivity, specificity, coherence and time relationship between the signals.

Results:  PPGr sensitivity for breath detection was [mean (SD)] >86(21)% and specificity >96(12)%. Respiratory detection in the macrocirculation (CVP, PVP and ABP) showed a sensitivity >83(29)% and specificity >93(12)%. The coherence between signals was high (0.75–0.99). The three measurement situations did not significantly influence sensitivity, specificity or time shifts between the PPGr, PVP, ABP, and the reference CVP signal despite changes in physiological data between measurements.

Conclusion:  A respiratory synchronous variation in PPG and all invasive pressure signals was detected. The reflection mode PPGr signal seemed to be a constant phenomenon related to respiration regardless of whether or not the subject was awake, anaesthetized or ventilated, which increases its clinical usefulness in respiratory monitoring.

Keyword
general anaesthesia, monitoring, photoplethysmography, positive-pressure ventilation, respiration
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-31542 (URN)10.1111/j.1399-6576.2005.00721.x (DOI)17342 (Local ID)17342 (Archive number)17342 (OAI)
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2017-12-13Bibliographically approved
5. Age and gender do not influence the ability to detect respiration by photoplethysmography
Open this publication in new window or tab >>Age and gender do not influence the ability to detect respiration by photoplethysmography
Show others...
2006 (English)In: Journal of clinical monitoring and computing, ISSN 1387-1307, E-ISSN 1573-2614, Vol. 20, no 6, 431-436 p.Article in journal (Refereed) Published
Abstract [en]

Objective  The non-invasive technique photopl- ethysmography (PPG) can detect changes in blood volume and perfusion in a tissue. Respiration causes variations in the peripheral circulation, making it possible to monitor breaths using an optical sensor attached to the skin. The respiratory-synchronous part of the PPG signal (PPGr) has been used to monitor respiration during anaesthesia, and in postoperative and neonatal care. Studies addressing possible differences in PPGr signal characteristics depending on gender or age are lacking.

Methods  We studied three groups of 16 healthy subjects each during normal breathing; young males, old males and young females, and calculated the concordance between PPGr, derived from a reflection mode PPG sensor on the forearm, and a reference CO2 signal. The concordance was quantified by using a squared coherence analysis. Time delay between the two signals was calculated. In this process, we compared three different methods for calculating time delay.

Results  Coherence values ≥0.92 were seen for all three groups without any significant differences depending on age or gender (p = 0.67). Comparison between the three different methods for calculating time delay showed a correlation r = 0.93.

Conclusions  These results demonstrate clinically important information implying the possibility to register qualitative PPGr signals for respiration monitoring, regardless of age and gender.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-37154 (URN)10.1007/s10877-006-9050-z (DOI)33808 (Local ID)33808 (Archive number)33808 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-13Bibliographically approved

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