Authors: Roberts BW, Kilgannon JH, Hunter BR, et al. Association Between Elevated Mean Arterial Blood Pressure and Neurologic Outcome After Resuscitation From Cardiac Arrest: Results From a Multicenter Prospective Cohort Study. CCM. 2019 Jan;47(1):93-100.
Reviewed by: Sara Stern-Nezer, MD, MPH; and Kyle Hobbs, MD
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Even in the era of TTM, a large number of post-cardiac arrest patients have poor outcomes, in part owing to the ongoing secondary brain injury that occurs after ROSC.
In these reviews, we consider additional targets to improve outcomes for survivors of cardiac arrest (CA). Increased MAP may have benefit to improve cerebral blood flow in tissue that lacks normal autoregulation and steroids may provide benefit to the sepsis-like inflammatory picture and relative adrenal insufficiency that develop after CA. The study below suggests that thinking beyond targeted temperature management after CA is necessary to continue improvement in patient outcomes.
Post-cardiac arrest hypotension is associated with increased mortality and worse neurological function, but the optimal BP for brain perfusion remains undetermined.
In this retrospective analysis of a prospective cohort of 280 patients who experienced in- and out-of-hospital cardiac arrest with ROSC >20 minutes, study authors examined the relationship between early elevated MAP and neurological outcome after CA.
Patients were dichotomized into low MAP (70-90mmHg) and high MAP (>90mmHg) groups; patients with MAP<70mmHg during the first 6 hours after ROSC were excluded. Primary outcome was good outcome (mRS<=3) at discharge. In both patient groups, 30% of patients had good outcome at discharge; a higher proportion of patients in the high MAP (42%) had good outcomes vs. the lower MAP (15%) group (p<0.001). This was also true for both secondary outcomes, including in-hospital mortality and four score >6 at 72hrs after ROSC, and remained true after adjusting for potential confounders. Moreover, a dose-response effect was seen between MAP and good neurological outcome. Of note, a higher proportion of patients with MAP 70-90mmHg had withdrawal of life support (58% vs 35%, p<0.001), but among patients who survived to discharge, MAP>90 remained an independent predictor of good outcome (p<0.001). The relationship was strongest in patients with a history of hypertension. The association was true in subgroup analyses looking at in- and out-of-hospital CA as well as shockable and non-shockable rhythms.
This study presents further evidence to support an association between early post-arrest MAP and neurological outcome at discharge. The increased strength of association in patients with a history of hypertension also points to the need to individualize MAP goals based on patient history and etiology of CA.
Longer duration at higher MAPs was more strongly associated with positive outcomes, but it is unclear whether altering MAP will improve outcomes or whether it simply reflects the degree of initial injury severity. Higher MAP may be associated with less brain injury during CA, with patients at higher MAP having sustained less injury initially.
The retrospective nature of this analysis precludes knowing if MAP has a causal relationship on outcome; however, it does suggest a need to revisit MAP goals after CA with a focus on randomized controlled trials in the future.