Estimation of Continuous Blood Pressure with Amplitude of Photoplethysmogram and Pulse Transit Time of Finger and Toe.

Seo,  Kwang Suk; Kim,  Jung Soo; Ahn,  Wonsik; Park,  Kwang Suk; Kim,  Hyun Jeong; Yum,  Kwang Won; Goo,  Eui Kyoung

doi:2007.53.2.159

Original Article

Korean Journal of Anesthesiology 2007;53(2):159-168.
DOI: https://doi.org/10.4097/kjae.2007.53.2.159

Estimation of Continuous Blood Pressure with Amplitude of Photoplethysmogram and Pulse Transit Time of Finger and Toe.

Kwang Suk Seo, Jung Soo Kim, Wonsik Ahn, Kwang Suk Park, Hyun Jeong Kim, Kwang Won Yum, Eui Kyoung Goo

¹Department of Dental Anesthesiology, Seoul National University Dental Hospital, Korea.
²Department of Biomedical Engineering, Seoul National University College of Medicine, Korea.
³Department of Anesthesiology and Pain Medicine, College of Medicine, Seoul National University Hospital, Seoul, Korea. aws@snu.ac.kr

Abstract

BACKGROUND
The amplitude (AMP) of Photoplethysmogram (PPG) is used as a marker of vasodilatation. The pulse transit time (PTT), which shows a good correlation with blood pressure (BP), is not strong enough to detect the changes in BP. This study examined the sensitivity of the combined effect of the finger and toe AMP, and the PTT of PPG as a marker of the changes in BP during general anesthesia.
METHODS
Forty patients receiving maxillofacial surgery under general anesthesia were enrolled in this study. During surgery, the intra-arterial BP, ECG, finger and toe PPG signals were measured. Using the R-wave from the ECG, the AMP and PTT was derived from PPG data. The correlation between BP and PPG parameters (AMP and PTT) were compared. New parameters that show high correlation with the BP were found. Regression equations for calculating the BP using the PPG parameters were formulated.
RESULTS
The new parameter, log (fingerAMP/toeAMP), showed the highest correlation in each patient (mean correlation coefficient in the systolic BP: -0.846, diastolic BP: -0.858). However, when the data from all 40 patients were combined, the correlation coefficient of the toe PTT was highest (systolic BP: -0.726, diastolic BP: -0.646). The regression equation showed the highest correlation between the actual BP and calculated BP when the toe PTT and log (fingerAMP/toeAMP) were included.
CONCLUSIONS
The AMP of the toe and finger PPG can be used to estimate the invasive continuous blood pressure.

Key Words: blood pressure; measurement; photoplethysmogram; pulse transit time