Reviewer: Dr Elif Ayduk Gövdeli

Name of the Study: Blood pressure and oxygenation targets in post-resuscitation care, a randomized clinical trial: the BOX trial

Published Congress: ESC 2022

Link : https://www.escardio.org/The-ESC/Press-Office/Press-releases/Trial-finds-no-benefit-of-raising-blood-pressure-target-in-post-cardiac-arrest-patients

Background:

Patients in coma after out-of-hospital cardiac arrest have an increased risk of death and neurological damage due to hypoxic brain injury. Previous studies have focused on temperature target, however there is limited research on optimal arterial blood pressure target.

Objective:

The aim of this study is to compare the effect of two different mean arterial blood pressure targets (77mmHg and 63mmHg), which are frequently used in clinical practice, on mortality and neurological function.

Methods:

789 adult patients in coma after resuscitation from out-of-hospital cardiac arrest of presumed cardiac cause were enrolled. They were randomised 1:1 to a blood pressure target of 63 mmHg or 77 mmHg. The trial was double-blinded in terms of blood pressure targets.

The primary outcome is all-cause mortality within 90 days or discharge from hospital with Cerebral Performance Category CPC 3 or 4 (defining dependence on others in daily activities or worse). The secondary outcome was determined as the blood 48-hour neuron-specific-enolase level to detect brain injury, all-cause mortality within three months, CPC, the modified Rankin Scale score to assess disability, and the Montreal Cognitive Assessment score (MoCA) to measure mild cognitive impairment.

Results:

The average age of the participants was 63 and 81% were male. The primary outcome was seen in 133 (34%) patients in the 77mmHg group and 127 (32%) patients in the 63mmHg group respectively (hazard ratio 1.08; 95% CI 0.84-1.37; p-value 0.56).

Neuron-specific-enolase levels were similar in both groups. At 3 months, there were no difference between two groups in survival (p-value 0.35), CPC (p-value 0.63), modified Rankin Scale (p-value 0.53) and MoCA (p-value 087).

Conclusion:

In patients surviving cardiac arrest, the blood pressure target of 77mmHg provides no additional benefit in terms of survival and neurological outcomes compared to the target of 63mmHg.

Interpretations:

In patients who survive cardiac arrest, low after-load supports cardiac recovery and also provides adequate perfusion pressure for the recovering brain. The BOX study did not demonstrate clinical benefit of a high blood pressure target compared to a low blood pressure target. These results support post-resuscitation treatment guidelines that recommend at least 65mmHg as the mean arterial blood pressure target.