Optimal mean arterial pressure for favorable neurological outcomes in survivors after extracorporeal cardiopulmonary resuscitation

Background: This study aimed to evaluate the optimal target of mean arterial pressure (MAP) for favorable neurological outcomes in patients who underwent extracorporeal cardiopulmonary resuscitation (ECPR). Methods: This was a retrospective, single-center, and observational study of adult patients who underwent ECPR during hospitalization between January 2013 and December 2019. The average MAP was defined as the sum of obtained MAPs divided by their obtained numbers of times during 6, 12, 24, 48, 72, and 96 hrs after cardiac arrest, respectively. The primary outcome was the neurological status upon discharge, as assessed by the Cerebral Performance Categories (CPC) scale (range from 1 to 5). Results: Ultimately, 253 patients were analyzed in this study. Among these patients, 144 (56.9%) survived until discharge from the hospital. Of these survivors, 104 patients had favorable neurologic outcomes (CPC 1 or 2). Overall, patients with favorable neurological outcomes tended to have a higher average MAP than those with poor neurological outcomes. Ensemble algorithms for machine learning revealed that age, Glasgow Coma Scale (GCS) on admission, duration of cardiopulmonary resuscitation (CPR) and average MAPs were significantly associated with neurological outcomes. Six models were established based on these variables and observation times. There was no significant difference in the predicted performance between the 6 hrs model and other models. The patients with average MAP around 75 mmHg had the least probability of poor neurologic outcomes in all the models. However, those with average MAPs below 60 mmHg had a high probability of poor neurological outcomes. Also, based on an increase in the average MAP, the risk of poor neurological outcomes tended to increase in patients with an average MAP greater than 75 mmHg. Conclusions: In this study, age, GCS on admission, CPR duration and average MAPs were identified to be associated with neurological outcomes. Especially, it is hypothesized that the average MAP during the initial 6 hrs may be associated with secondary cerebral injury. Therefore, it is theorized that at an early stage, maintaining the survivor’s MAP to about 75 mmHg may be important for neurological recovery after ECPR.