Abstract 2055: Non-Invasive Measurements for Predicting Duration of Untreated Cardiac Arrest
Objective. Initial chest compression rather than defibrillation has evolved as the initial intervention when the duration of untreated cardiac arrest exceeds 4 min. Accordingly, we sought methods by which the duration of untreated cardiac arrest could be reliably estimated and communicated to the rescuer. Both AMSA (the amplitude spectrum area) together with measurements of tissue PCO2 in the buccal mucosa (PBUCO2) were investigated. We hypothesized that decreases in AMSA, reflecting reduced myocardial electrical function, and increases in PBUCO2, reflecting the severity of anaerobic metabolism, would fulfil this need.
Materials and Methods. In 9 domestic male pigs weighing 41 ± 2 kg, ventricular fibrillation (VF) was electrically induced and untreated for 15 min. AMSA was analyzed by fast Fourier transform from the ECG signal obtained through conventional precordial electrodes. PBUCO2 was continuously measured utilizing a miniature optical sensor system (CO2 ABG Module, Vasomed, Minneapolis, MN) applied non-invasively on to the buccal mucosa.
Results. After 3 min of untreated VF, the AMSA value decreased significantly (p < 0.01, Figure⇓). PBUCO2 progressively increased, exceeding threshold levels after 4 min. AMSA and PBUCO2 were remarkably highly correlated with the durations of untreated cardiac arrest (r = 0.99 and r = 0.92, p < 0.0001) and with each other (r = −0.95, p < 0.0001).
Conclusion. AMSA and PBUCO2 both represent methods by which the duration of untreated cardiac arrest may be identified such as to prompt rescuer to immediately defibrillate or begin chest compression.