Photoplethysmographic detection of a spontaneous pulse during manual experimental cardiopulmonary resuscitation

Abstract

Introduction: Pulse checks by manual palpation during cardiopulmonary resuscitation (CPR) are challenging, can be timeconsuming and interrupt chest compressions. Long interruptions for pulse checks can negatively impact CPR outcome. We have investigated photoplethysmography (PPG) for non-invasive pulse detection support during compressions, which could reduce the interruptions and thereby improve outcome. Methods: Ventricular fibrillation (VF) was induced in 10 anesthetized pigs, followed by 2min ofmanual CPR targeting a 100/min compression rate. Next, defibrillation shocks were delivered, each followed by 2min of manual CPR. Infrared lip PPG signals were measured with aortic blood pressure (ABP) as a reference, and an accelerometer on the chest measured the compressions. In retrospect, spectrograms and time traces of the signals were analysed. Spectrograms show which frequencies are present in a signal over time. Results and discussion: Five animals had return of spontaneous circulation (ROSC). The spontaneous pulse rate (PR) could be recognized in the spectrograms of the PPG signal and distinguished from the manual compression rate, provided that the compression rate and spontaneous pulse rate were different (Fig. 1a). Furthermore, an increased complexity could be observed in the PPG signal time trace when a spontaneous pulse appeared, as confirmed by the ABP signal, provided that the characteristics of the manual compressions remained unaltered (Fig. 1b and c). Fig. 1. PPG signal during manual CPR. (a) Spectrogram. (b) Compressions during cardiac arrest. (c) Compressions with underlying spontaneous pulse.