Optimal mean arterial pressure in comatose survivors of out-of-hospital cardiac arrest: An analysis of area below blood pressure thresholds

Abstract

Aim of the study: To determine the optimal mean arterial pressure (MAP) during the early-to-intermediate phase care of comatose survivors of out-of-hospital cardiac arrest (OHCA).

Methods: We identified consecutive comatose survivors of OHCA with an initial shockable rhythm. Using blood pressure-over-time plots, we calculated the area below pre-specified MAP thresholds (ABT; mmHg*hours) during the first 96 h of admission. We used incremental MAP thresholds ranging between 65 and 85 mmHg. Logistic regression analyses were used to examine the association between ABT and clinical outcomes for each MAP threshold and to adjust for age, duration of cardiac arrest, and bystander CPR. The primary outcome was severe neurological dysfunction as defined by a cerebral performance category (CPC) ≥3.

Results: We identified 122 consecutive OHCA patients meeting inclusion criteria. The rate of the primary outcome was 33%. There was a significant association between ABT and the rate of the primary outcome when MAP thresholds of 60 (p = 0.01), 65 (p < 0.01), 70 (p < 0.01), 75 (p < 0.01), and 80 mmHg (p < 0.01) were used. This association was lost once a MAP threshold of 85 mmHg was reached (p = 0.63). In the adjusted analysis, the association between ABT and the primary outcome was no longer present when the MAP threshold reached 75 mmHg.

Conclusions: In comatose survivors of OHCA with an initial shockable rhythm, higher ABT is associated with increased rates of severe neurological dysfunction when MAP thresholds <75 mmHg are used. The current findings support the hypothesis that higher MAP targets (≥75 mmHg) may be indicated in this patient population.

Keywords: Anoxic brain injury; Hemodynamic targets; Out-of-hospital cardiac arrest; Post-cardiac arrest care; Resuscitation.