Finger Photoplethysmography to Monitor Chest Compression Rate during Out-of-Hospital Cardiac Arrest

Cardiac arrest survival rate is strongly associated with high quality cardiopulmonary resuscitation (CPR), which includes chest compression (CC) rates above 100 min^-1. Currently, defibrillator monitors use external hardware such as CPR assist pads to monitor CC rate and give feedback to the rescuer. The photoplethysmogram (PPG) provides information about the level of oxygen saturation in blood and can be easily recorded by a pulse oximeter in the fingertip. The aim of this study was to analyze the feasibility of using the finger PPG to monitor the presence and rate of CCs in out-of-hospital cardiac arrest (OHCA). The dataset used in the study consisted of 112 segments from 46 OHCA patients, with a total duration of 256 min and 27667 CCs. The method is based on the power spectral density analysis of 10 s segments of the PPG. CC presence was determined through thresholding, and CC rate was computed applying a maximum slope criterion. The dataset was divided patient-wise intro training (60%) and testing (40%) sets. For the test set the algorithm presented a sensitivity and a positive predictive value of 85.2% and 98.1% respectively for CC detection, a CC rate error of 2.8 (6.8)min^-1 and 3.4% of the values with an error above 10%.