Abstract Body: Background: Animal and recent clinical studies have identified differences in the hemodynamic response to epinephrine between survivors and non-survivors. We aimed to evaluate how sequential epinephrine responses during CPR relate to survival outcomes in an animal model of cardiac arrest with standard chest compression depth.
Hypothesis: Hemodynamic responses to sequential epinephrine doses during CPR change over time and are associated with ROSC.
Methods: We retrospectively analyzed hemodynamic data acquired in pediatric swine models (Sus scrofa, 9-13kg) of asphyxia-associated cardiac arrest treated with CPR (n=69). Epinephrine (0.02mg/kg) was administered every 3-4min starting 2 minutes into CPR. Defibrillation was attempted after 10 or 15min of CPR based off the cohort. Manual or mechanical chest compressions were performed at a set depth and rate throughout CPR. Median and interquartile ranges were calculated for diastolic blood pressure (DBP), systolic blood pressure (SBP), end-tidal CO₂ (ETCO₂), pulse pressure (SBP-DBP), and right atrium pressure (RaP) for each 15-second epoch and the change between pre-epinephrine values and each 15-second value for the 3m post-epinephrine were determined. Wilcoxon rank-sum tests were used for sequential Epi dose to compare survivors and non-survivors at each epoch. Trends across Epi doses within both groups were compared using Kruskal-Wallis test with Bonferroni correction.
Results: Sixty-nine animals (survivor 42, non-survivor 27) were included. Baseline characteristics were similar between groups. Comparisons between survivors and non-survivors for the first 3 Epi doses are show in in Figure 1. During the evaluation period, non-survivors had progressively diminished responses to Epi as noted by lower delta DBP and SBP. RaP showed no significant change. Non-survivors exhibited progressive decline in median pulse pressure with each subsequent dose (Figure 2), whereas survivors maintained stable pulse pressure with no significant change between the first and the third doses.
Discussion: In an animal model of asphyxia-associated cardiac arrest, the response to successive epinephrine administration diverge between survivors and non-survivors. Although the two groups have comparable responses to the first Epi dose, non-survivors have lower blood pressures and a decreased response to subsequent Epi doses. Future studies should explore alternative resuscitation strategies for animals based off Epi responsiveness.