Introduction:
Comatose survivors of OHCA develop a post cardiac arrest syndrome (PCAS) characterized by myocardial dysfunction and cerebrovascular dysregulation. Hemodynamic derangements related to PCAS can jeopardize cerebral oxygen delivery and therefore impair neurologic recovery. However, optimal hemodynamic targets to ensure adequate cerebral oxygen delivery following OHCA remain undefined. Accordingly, we examined the relationship between cardiac index (CI), mean arterial pressure (MAP), and regional cerebral oxygen saturation (rO
2
%) following OHCA.
Methods:
CAPITAL-RETURN was a prospective, single-center observational study examining hemodynamics in comatose survivors of OHCA undergoing targeted temperature management after an initial shockable rhythm. Between August 2016 and December 2017, comatose survivors of OHCA underwent continuous, blinded, non-invasive monitoring of CI and rO
2
% using bioimpedance (Cheetah Medical, Portland, OR, USA) and near-infrared spectroscopy (Covidien, Boulder, CO, USA), respectively, for 96 hours after intensive care unit admission. In the present study, we examined the relationship between CI, MAP, and rO
2
% using multivariable linear regression.
Results:
In 56 patients in this analysis, the mean CI and MAP during the first 96 hours of intensive care unit admission were 3.2±0.5 L/min/m
2
and 76±6 mmHg, respectively (Figure). The mean rO
2
% was 63±9% and increased over time (+0.1% per hour; p<0.001). Higher CI was associated with improved rO
2
% (+3.2% per L/min/m2 increase in CI; p<0.0001). There was no association between MAP and rO
2
% (p=0.42). After adjustment for MAP, the association between CI and rO
2
% remained significant (+3.1% per L/min/m2 increase in CI; p<0.0001).
Conclusion:
In comatose survivors of OHCA with an initial shockable rhythm, a higher CI is associated with improved rO
2
%. Further studies are needed to determine whether CI targets improve rO2% and neurologic outcomes following OHCA.
The impact of extracorporeal membrane oxygenation on cerebral oxygen delivery during cardiac arrest: a case series