Combined end-tidal CO₂ and diastolic blood pressure-guided CPR improves survival from cardiac arrest in porcine model.

Abstract

To determine whether dynamically increasing both chest compression depth and rate in response to real-time physiologic feedback-guided by end-tidal CO₂ (ETCO₂) alone or in combination with diastolic blood pressure (DBP)-improves resuscitation outcomes compared with standard cardiopulmonary resuscitation (CPR) with fixed compression mechanics, in a porcine ventricular fibrillation (VF) arrest model. Conventional "one-size-fits-all" CPR employs fixed compression depth and rate, failing to adapt to individual physiologic needs. ETCO₂ serves as a surrogate for pulmonary perfusion, while DBP reflects myocardial perfusion. However, the combined use of ETCO₂ and DBP as dual physiologic targets to guide dynamic adjustment of compression depth and rate during CPR has not been previously studied, and its efficacy remains unknown. Thirty healthy Landrace pigs (14-16 weeks old, 35-40 kg) underwent 10 min of untreated VF. Animals were randomized to one of three CPR strategies (n = 10 per group): (1) Standard CPR: fixed compression depth (5 cm) and rate (100 compressions per minute); (2) ETCO₂-guided CPR: adjustments every 30 s to maintain ETCO₂ ≥ 10 mmHg; (3) Combined-guided CPR: adjustments every 30 s to maintain both ETCO₂ ≥ 10 mmHg and DBP ≥ 30 mmHg. Defibrillation and epinephrine were administered per protocol. Resuscitation was continued for up to 20 min or until ROSC was achieved. Primary outcome was 24-hour survival. Secondary outcomes included ROSC, neurological outcomes, and hemodynamic parameters. Group comparisons used one-way ANOVA, Kruskal-Wallis, Fisher's exact test, and log-rank test. Repeated measures were analyzed using generalized estimating equations and linear mixed-effects models. Return of spontaneous circulation (ROSC) rates were 100 %, 90 %, and 50 % in Combined-guided, ETCO₂-guided, and Standard groups, respectively. Twenty-four-hour survival was 80 %, 50 %, and 20 % (Combined vs. Standard, p = 0.023; ETCO₂ vs. Standard, p = 0.038; Combined vs. ETCO₂, p = 0.162). Combined guidance yielded superior Cerebral Performance Category scores (median 1.0 vs. 3.0; p = 0.022) and lower S100B levels (3585 vs. 4216 pg/mL; p = 0.022), while differences between Combined and ETCO₂ groups did not reach significance. Highest ETCO₂ (16.1 ± 0.8 mmHg), DBP (32.0 ± 0.5 mmHg), mean arterial pressure (36.7 ± 0.5 mmHg), and coronary perfusion pressure (22.5 ± 0.5 mmHg) were shown with Combined-guided CPR. No increase in major injuries was observed. Physiologic-feedback CPR-achieved by dynamically adjusting both compression depth and rate based on ETCO₂ and DBP targets-significantly improved survival, neurological outcome, and hemodynamics compared to standard CPR in this porcine VF cardiac arrest model. Although combined ETCO₂ and DBP guidance resulted in significantly better physiological perfusion parameters compared to ETCO₂ guidance alone, observed differences in survival and neurological outcomes between these two groups did not reach statistical significance.