What is the optimal prehospital blood pressure level after cardiac arrest? A retrospective cohort study on the association of blood pressure and mortality among patients treated with vasoactive medication.

Abstract

Vasoactive drugs are often initiated during prehospital post-resuscitation care by Helicopter Emergency Medical Services (HEMS). Evidence is limited regarding treatment targets to ensure optimised survival. Hence, guidelines remain vague. We aimed to compare 30-day and 1-day mortality based on systolic blood pressure (SBP) attained after the administration of vasoactive medication during prehospital post-resuscitation care. We conducted a retrospective registry-based cohort study including post-resuscitation care cases attended by a HEMS-physician in which vasoactive treatment was used between 1.1.2012 and 31.8.2019. Patients were categorised according to SBP at handover to hospital: <100, 100-119, 120-140, >140 mmHg. Multivariate logistic regression was used to assess 30- and 1-day mortality, while controlling for age, sex, time to return of spontaneous circulation, presumed cardiac aetiology for arrest, whether the arrest was witnessed, initial rhythm and presence of bystander cardiopulmonary resuscitation. 3029 post-resuscitation cases were attended by HEMS. In these cases, a total of 1861 patients received vasoactive medication. 1665 patients had necessary variables recorded and were included in our primary analysis. Compared to hypotensive (SBP < 100 mmHg), odds ratios for 30-day mortalities were 0.54 (0.37-0.80), 0.58 (0.40 - 0.85), and 0.78 (0.51-1.18) in respective SBP categories of 100-119, 120-140 and > 140 mmHg. Furthermore, odds ratios for 1-day mortalities were 0.42 (0.28-0.61), 0.42 (0.29-0.61), and 0.36 (0.23-0.55), respectively. Normotension (SBP 100-140 mmHg) was associated with lower mortality compared to hypo- and hypertensive patients. This can be considered a basis for future prospective trials.