Survival with one versus three centimeters of active decompression during automated head-up CPR in a porcine cardiac arrest model

Background : Automated head-up (AHUP) CPR, combining head/thorax elevation, active compression-decompression CPR, and an impedance threshold device, has shown improved survival with favorable neurological outcomes versus conventional (C) CPR. The optimal degree of active lift (AD) during AHUP-CPR to optimize survival remains unknown. This study focused primarily on 24-hour survival with 1-cm of active lift (AL-1cm) with a rectilinear waveform versus 3-cm of active lift (AL-3cm) with a trapezoidal waveform. Methods : Anesthetized pigs (n=24, ∼ 40kg) were randomized to AL-1cm or AL-3cm after 10 minutes of ventricular fibrillation. CPR began with 2 minutes of C-CPR (21% AP depth, sinusoidal waveform, 100/min), followed by 18 minutes of AHUP-CPR using the assigned AL. Asynchronous ventilation (10 ml/kg, 10/min) was provided. Epinephrine and amiodarone were administered after 19 minutes of CPR with defibrillation 1 minute later. Primary outcome : 24-hour survival; Secondary outcomes: return of spontaneous circulation (ROSC), hemodynamics, epinephrine response, and neurological function (Neurological Deficit Score [NDS], 0 = normal, 320 = death). Statistical analyses included t-test, Kaplan-Meier, log-rank, and Mann-Whitney U tests. Results : ROSC occurred in 6/12 pigs with AL-1cm vs 12/12 with AL-3cm (p=0.03), and 24-hour survival rates were 16.7% vs 41.7%, respectively (p=0.04). Hemodynamics, ETCO2, epinephrine response, and changes in rSO2 values were significantly higher with AL-3cm. NDS was 286 ± 79 (AL-1cm) vs 213 ± 130 (AL-3cm, p=0.09). Conclusion 24-hr survival rates were significantly higher with AL-3 cm vs AL-1cm during AHUP-CPR. Together with improved hemodynamics observed with AL-3cm, these outcomes underscore the critical importance of AL-3cm to optimize AHUP-CPR.