Pilot investigation of photoplethysmographic signals and blood oxygen saturation values during blood pressure cuff-induced hypoperfusion

P.A Kyriacou,K Shafqat,S.K Pal

doi:10.1016/j.measurement.2009.02.005

P.A Kyriacou, K Shafqat + Show 1 more

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https://doi.org/10.1016/j.measurement.2009.02.005

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Journal: Industrial Metrology	Publication Date: Mar 9, 2009
Citations: 21	License type: cc-by

Affiliation: City, University of London

Abstract

Photoplethysmography (PPG) is a non-invasive electro-optical technique widely used in the monitoring of the pulsations associated with changes in blood volume in a peripheral vascular bed. The technique is based on the absorption properties of vascular tissue when it is transilluminated by light. Photoplethysmography is also used in the estimation of arterial blood oxygen saturation ( SpO 2 ) by pulse oximetry where the technique relies on the presence of adequate peripheral arterial pulsations. The aim of this study was to investigate (14 healthy volunteers) the effect of pressure cuff-induced hypoperfusion on PPG signals and SpO 2 s using a custom made finger blood oxygen saturation PPG / SpO 2 sensor and a commercial finger pulse oximeter. PPG signals with high signal-to-noise ratios were obtained from all induced pressures prior to full brachial occlusion. An Analysis of Variance (ANOVA) on ranks showed that there are statistically significant differences ( p < 0.05 ) between the PPGs in the low pressures (0–80 mmHg) than those in the upper pressures (90–150 mmHg). Both pulse oximeters showed gradual decrease of saturations during induced hypoperfusion which demonstrate the direct relation between blood volumes (PPG amplitudes), arterial vessel stenosis and blood oxygen saturation. The custom made pulse oximeter was found to be more sensitive to SpO 2 changes than the commercial pulse oximeter especially at high occluding pressures.

Highlights

Photoplethysmography is a non-invasive optical technique widely used in the study and monitoring of the pulsations associated with changes in blood volume in a peripheral vascular bed [1,2,3,4,5,6,7,8]
A Kruskal–Wallis One Way Analysis of Variance (ANOVA) was performed to see if there was any significant difference between the mean PPG amplitudes at all induced pressures
The systematic occlusion of the brachial artery caused the volume of blood reaching the finger to decrease which was obvious from the changes in the amplitude of the ac PPG signal obtained from the custom made finger probe

Summary

Introduction

Photoplethysmography is a non-invasive optical technique widely used in the study and monitoring of the pulsations associated with changes in blood volume in a peripheral vascular bed [1,2,3,4,5,6,7,8]. Photoplethysmography is used in the estimation of arterial blood oxygen saturation ðSpO2Þ by pulse oximetry. Pulse oximeters estimate arterial oxygen saturation by shining light at two different wavelengths, red and infrared, through vascular tissue. In this method, the pulsatile photoplethysmographic (ac PPG) signal associated with cardiac contraction is assumed to be attributable solely to the arterial blood component. The amplitudes of the red and infrared ac PPG signals are sensitive to changes in arterial oxygen saturation because of differences in the light absorption of oxygenated and deoxygenated haemoglobin at these two wavelengths. From the ratios of these amplitudes, and the corresponding dc photoplethysmographic components, arterial blood oxygen saturation ðSpO2Þ is estimated. The technique of pulse oximetry relies on the presence of adequate peripheral arterial pulsations, which are detected as photoplethysmographic (PPG) signals [9]

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