[The role of pulse oximetry plethysmographic waveform monitoring as a marker of restoration of spontaneous circulation:a pilot study].

OBJECTIVE:To investigate the feasibility of using pulse oximetry plethysmographic waveform (POP) to identify the restoration of spontaneous circulation (ROSC) during cardiopulmonary resuscitation (CPR). METHODS:An observational research was conducted. A porcine model of ventricular fibrillation (VF) arrest was reproduced. After 3 minutes of untreated VF, animals received CPR according to the latest CPR guidelines, providing chest compressions to a depth of 5 cm with a rate of 105 compressions per minute and instantaneous mechanical ventilation. After 2 minutes of CPR, animals were defibrillated with 100 J biphasic, followed by continuous chest compressions. Data of hemodynamic parameters, partial pressure of end-tidal carbon dioxide (PETCO₂) and POP were collected. The change in POP was observed, and the characteristics of changes of the waves were recorded during the peri-CPR period using the time and frequency domain methods. RESULTS:VF was successfully induced in 6 pigs, except 1 death in anesthesia induction period. (1) After VF, invasive blood pressure waveform and POP of the animals disappeared. PETCO₂was (18.83 ± 2.71) mmHg (1 mmHg=0.133 kPa), and diastolic arterial pressure was (23.83 ± 5.49) mmHg in compression stage. Animals attained ROSC within 1 minute after defibrillation, with PETCO₂[(51.83 ± 9.35) mmHg] and diastolic arterial pressure [(100.67 ± 10.97) mmHg] elevated significantly compared with that of compression stage (t1 = 8.737, t2 = 25.860, both P = 0.000), with appearance of arterial blood pressure waveform.(2) Characteristic changes in POP were found in all experimental animals. During the stages of induced VF, compression, ROSC, and compression termination, POP showed characteristic waveform changes. POP showed disappearance of waveform, regular compression wave, fluctuation hybrid and stable pulse wave in time domain method; while in the frequency domain method waveform disappearance, single peak of compression, double or fusion peak and single peak of pulse were observed. CONCLUSIONS:Analysis of POP using time and frequency domain methods could not only quickly detect cardiac arrest, but also show a role as a feasible, non-invasive marker of ROSC during CPR.