Hemodynamic targets during therapeutic hypothermia after cardiac arrest: A prospective observational study

Abstract

Aim: In analogy with sepsis, current post-cardiac arrest (CA) guidelines recommend to target mean arterial pressure (MAP) above 65mmHg and SVO2 above 70%. This is unsupported by mortality or cerebral perfusion data. The aim of this study was to explore the associations between MAP, SVO2, cerebral oxygenation and survival. Methods: Prospective, observational study during therapeutic hypothermia (24. h - 33. °C) in 82 post-CA patients monitored with near-infrared spectroscopy. Results: Forty-three patients (52%) survived in CPC 1-2 until 180 days post-CA. The mean MAP range associated with maximal survival was 76-86mmHg (OR 2.63, 95%CI [1.01; 6.88], p=0.04). The mean SVO2 range associated with maximal survival was 67-72% (OR 8.23, 95%CI [2.07; 32.68], p=0.001). In two separate multivariate models, a mean MAP (OR 3.72, 95% CI [1.11; 12.50], p=0.03) and a mean SVO2 (OR 10.32, 95% CI [2.03; 52.60], p=0.001) in the optimal range persisted as independently associated with increased survival. Based on more than 1625000 data points, we found a strong linear relation between SVO2 (range 40-90%) and average cerebral saturation (R2 0.86) and between MAP and average cerebral saturation for MAP's between 45 and 101mmHg (R2 0.83). Based on our hemodynamic model, the MAP and SVO2 ranges associated with optimal cerebral oxygenation were determined to be 87-101mmHg and 70-75%. Conclusion: we showed that a MAP range between 76-86mmHg and SVO2 range between 67% and 72% were associated with maximal survival. Optimal cerebral saturation was achieved with a MAP between 87-101mmHg and a SVO2 between 70% and 75%. Prospective interventional studies are needed to investigate whether forcing MAP and SVO2 in the suggested range with additional pharmacological support would improve outcome.