The association between early impairment in cerebral autoregulation and outcome in a pediatric swine model of cardiac arrest.

aimsEvaluate cerebral autoregulation (CAR) by intracranial pressure reactivity index (PRx) and cerebral blood flow reactivity index (CBFx) during the first four hours following return of spontaneous circulation (ROSC) in a porcine model of pediatric cardiac arrest. Determine whether impaired CAR is associated with neurologic outcome.

methodsFour-week-old swine underwent seven minutes of asphyxia followed by ventricular fibrillation induction and hemodynamic-directed CPR. Those achieving ROSC had arterial blood pressure, intracranial pressure (ICP), and microvascular cerebral blood flow (CBF) monitored for 4 h. Animals were assigned an 8 -h post-ROSC swine cerebral performance category score (1 = normal; 2-4=abnormal neurologic function). In this secondary analytic study, we calculated PRx and CBFx using a continuous, moving correlation coefficient between mean arterial pressure (MAP) and ICP, and between MAP and CBF, respectively. Burden of impaired CAR was the area under the PRx or CBFx curve using a threshold of 0.3 and normalized as percentage of monitoring duration.

resultsAmong 23 animals, median PRx was 0.14 [0.06,0.25] and CBFx was 0.36 [0.05,0.44]. Median burden of impaired CAR was 21% [18,27] with PRx and 30% [17,40] with CBFx. Neurologically abnormal animals (n = 10) did not differ from normal animals (n = 13) in post-ROSC MAP (63 vs. 61 mmHg, p = 0.74), ICP (15 vs. 14 mmHg, p = 0.78) or CBF (274 vs. 397 Perfusion Units, p = 0.12). CBFx burden was greater among abnormal than normal animals (45% vs. 24%, p = 0.001), but PRx burden was not (25% vs. 20%, p = 0.38).

conclusionCAR is impaired early after ROSC. A greater burden of CAR impairment measured by CBFx was associated with abnormal neurologic outcome.CHOP Institutional Animal Care and Use Committee protocol 19-001327.