Introduction: Hemodynamic-directed CPR (HD-CPR) improves intra-arrest hemodynamics and 24-hour survival outcomes. The increased vasoactive dosing in HD-CPR may worsen cerebral blood flow (CeBF). We hypothesized that 3 different CPR strategies may variably impact intra-arrest CeBF, post-arrest cardiac function, and 7-day outcomes. Methods: 4-week-old swine (sus scrufa) underwent 7-minutes of asphyxia, induction of ventricular fibrillation arrest, and 15-min of CPR. Pigs were randomized to 3 CPR strategies (n=15 each). 1) HDhigh: a) chest compression depth (CCD) titrated to systolic BP ~110mmHg and b) vasoactives (epinephrine and vasopressin) titrated to diastolic BP ~45mmHg; 2) HDlow: BP titrated to ~80/30; 3) AHA: fixed CCD and vasoactive interval. Six shams underwent anesthesia and instrumentation without cardiac arrest. We assessed intra-arrest invasive laser doppler CeBF (normalized to pre-arrest flow; rCeBF), post-return of spontaneous circulation (ROSC) left ventricular (LV) systolic function by apical 4 strain and 7-day survival. Mixed-effect linear regression models with CPR group as a fixed effect, a spatial exponential covariance structure to account for repeated observations and post-hoc Tukey’s test or a Kruskal-Wallis tests were used. Results: CCD differed among CPR strategies (overall P< 0.001; AHA vs HDhigh point estimate +4.4±1.8mm, P=0.06) as did vasoactive doses (HDhigh 9 7-10 v. HDlow 8 5-9 v. AHA 4 4-4, p< 0.001). Intra-arrest rCeBF differed among groups (overall P=0.02; AHA vs HDhigh point estimate +40.2±14.5%, P=0.02) as did 1-hour post-ROSC LV function (HDhigh -15.7% -19.8,-12.7 v. HDlow -13.9% -16.4,-12.8 v. AHA -12.8% -14.9,-9.5 v. sham -20.3% -21.9, -17.5, p=0.025). 7-day survival did not differ among strategies (HDhigh 9/15 v. HDlow 5/15 v. AHA 7/15 p=0.4). Conclusions: In this randomized preclinical trial of different physiology-directed and guideline-based resuscitation strategies, animals targeting the highest intra-arrest BP had more vasoactive doses and lower intra-arrest rCeBF compared to AHA CPR, yet improved post-ROSC cardiac function (more negative strain). There were no differences in 7-day survival. Future studies should evaluate optimal CPR strategies to improve ROSC, intra-arrest CBF, post-arrest cardiac and neurologic function.
Herrmann et al. (Sun,) studied this question.