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

Abstract

Objectives: 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.

Background: 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.

Methods: 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.

Results: 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.

Conclusions: 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.