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 SVO 2 above 70%. This is unsupported by mortality or cerebral perfusion data. The aim of this study was to explore the associations between MAP, SVO 2, 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 SVO 2 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 SVO 2 (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 SVO 2 (range 40-90%) and average cerebral saturation (R 2 0.86) and between MAP and average cerebral saturation for MAP's between 45 and 101mmHg (R 2 0.83). Based on our hemodynamic model, the MAP and SVO 2 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 SVO 2 range between 67% and 72% were associated with maximal survival. Optimal cerebral saturation was achieved with a MAP between 87-101mmHg and a SVO 2 between 70% and 75%. Prospective interventional studies are needed to investigate whether forcing MAP and SVO 2 in the suggested range with additional pharmacological support would improve outcome.