Spectral Characteristics and Parameters of Pulse Oximetry Waveforms for Assessing Resuscitation Status

Real-time assessment of physiological resuscitation status is critical for guiding personalised cardiopulmonary resuscitation (CPR) and avoiding unnecessary harm from prolonged chest compressions. Non-invasive, objectively trackable tools for this purpose remain limited.

This multicentre retrospective study (2013-2018) included 451 adult patients with cardiac arrest (497 CPR episodes) from 14 Chinese tertiary hospitals, comprising 158 Out-of-Hospital Cardiac Arrest (OHCA) episodes with prehospital SpO₂/ECG monitoring continued upon ED arrival and full pulse oximetry plethysmography (POP)/ECG/end-tidal carbon dioxide (ETCO₂) monitoring established in the ED, and 339 In-Hospital Cardiac Arrest (IHCA) episodes occurring in the ED. We analysed POP waveforms across four statuses: compression-only (CC), chest compression with return of spontaneous circulation (CC+ROSC, spontaneous circulation during ongoing compressions), non-compression without ROSC, and spontaneous circulation-only (SC). Time-domain (area under the POP curve [POP_AUC]) and frequency-domain spectral features were evaluated against clinically documented ROSC.

A frequency-domain "hybrid" pattern during the CC+ROSC identified ROSC with 100% specificity (PPV 1.000). In CC status,POP_AUC was higher in stable-ROSC than unstable-ROSC (3232.2±1008.2 vs. 2769.6±1013.0 PVPG, P=0.007). The POP_AUC was lower in CC+ROSC status than in SC status for stable-ROSC (2768.2±997.8 vs. 3335.8±842.4 PVPG, P=0.001), but the reverse was observed for unstable-ROSC (2697.5±941.0 vs. 1338.1±952.6 PVPG, P<0.001). POP waveforms disappearance with concurrent ECG presence identified pulseless electrical activity with 100% specificity.

Pulse oximetry plethysmography waveform analysis-using signals already available on standard monitors-may provide a non-invasive, real-time approach that may help identify ROSC during ongoing compressions and distinguish between stable and unstable circulation.