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

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.