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The influence of breathing pattern in ventilation monitoring using photoplethysmography
Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Objective. The present study aimed at determining the relative influences of tidal volume and thoraco-abdominal separation (relative thoracic and abdominal contribution to the tidal volume) on the respiratory induced intensity variations (RIIV) of the photoplethysmographic (PPG) signal. The effects were studied in two body positions.

Methods. Respiratory inductive plethysmography (RIP) was used for quantifying thoracoabdominal separation and for assessing tidal volumes. 10 subjects were trained to perform widely varying degrees of thoraco-abdominal separations at different tidal volumes. The relationship between the RIIV signal peak-to-peak value (measured at the forearm), and the tidal volume and separation was investigated in two body positions with the use of multiple linear regression.

Results. Larger tidal volume and more thoracic contribution to respiration were found to increase the RIIV peak-to-peak value (p<0.0005). In the supine position, tidal volume had a stronger influence than separation, and in the sitting position, the opposite was seen.

Conclusions. The effects on the RIIV signal from changes in thoraco abdominal separation and tidal volume are of similar magnitude. In the supine position, the influence of separation is less than in the sitting position, but the regression model fit is reduced. PPG is a promising technique for monitoring tidal volumes. However, in situations where the relative thoracic and abdominal contributions are likely to vary, the tidal volume information is less reliable.

National Category
Engineering and Technology
URN: urn:nbn:se:liu:diva-88950OAI: diva2:606449
Available from: 2013-02-19 Created: 2013-02-19 Last updated: 2013-02-19
In thesis
1. Photoplethysmography in multiparameter monitoring of cardiorespiratory function
Open this publication in new window or tab >>Photoplethysmography in multiparameter monitoring of cardiorespiratory function
2000 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Photoplethysmography (PPG) is an optical, non-invasive method to assess tissue blood volume/perfusion. When measured on human skin, the PPG signal includes both cardiac synchronous variations (AC) and respiratory induced intensity variations (RIIV). This makes the PPG signal appropriate for cardiorespiratory monitoring, as a single non-invasive sensor extracts both cardiac and respiratory information.

In this thesis, the origin of the RIIV signal is discussed, and invasive measurements of pressures in the circulatory system support the hypothesis of a venous origin. Important factors are intrathoracic and intra-abdominal pressure fluctuations, affecting venous return from the extrathoracic veins and the peripheral venous bed.

Previous reports have demonstrated a possibility to extract the RIIV signal for assessing respiratory rates. A more effective and reliable monitoring would be achieved if tidal volumes could be estimated from the PPG signal in addition to respiratory rates. This would provide a possibility to calculate and detect ventilatory trends. A relationship between the RIIV amplitude and the tidal volume was hypothesised, demonstrated in healthy subjects and verified in a theoretical (Windkessel) model of the circulatory system. Other factors than tidal volume influence intrathoracic and intra-abdominal pressures. Effects of thoraco-abdominal separation, posture and respiratory rate were observed, and their influence in tidal volume/ventilation monitoring was discussed.

Monitoring the cardiorespiratory function is essential in the postoperative and neonatal care environments. Studies have been performed in clinical settings including comparisons between the PPG method and more established monitoring systems. PPG was found to be suitable for monitoring heart and respiratory rates in these environments.

The arterial blood pressure contains respiratory related information, including heart rate fluctuations (respiratory sinus arrhythmia, RSA) and respiratory variations in cardiac stroke volume. These phenomena are seen in the PPG signal as frequency and amplitude modulation of the AC signal. An algorithm based on pattern recognition (neural networking) is presented, in which these respiratory components are extracted and combined with the RIIV signal. As the respiratory components are of different origins, the neural network algorithm is robust and more accurate for breath detection than algorithms utilising the components separately.

The main purposes of cardiorespiratory monitoring are to detect pathologic minute ventilation, apnoea, hypoxaemia, cardiac arrest, arrhythmia, and trends in heart rate. By using PPG, simultaneous information about heart rate, respiratory rate and tidal volume is obtained. Furthermore, as the measurement of arterial oxygen saturation by PPG is well established, a good coverage of the cardiorespiratory function can be obtained from a single non-invasive sensor.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet, 2000. 63 p.
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 629
National Category
Medical and Health Sciences
urn:nbn:se:liu:diva-29446 (URN)14793 (Local ID)91-7219-715-3 (ISBN)14793 (Archive number)14793 (OAI)
Public defence
2000-04-28, Elsa Brändströms sal, Universitetssjukhuset, Linköping, 13:15 (Swedish)
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2013-02-19

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Johansson, AndersStrömberg, Tomas
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