Abstract Body: BACKGROUND: In the post-resuscitation phase, cardiac arrest patients develop a systemic inflammatory response and fever is likely if not actively treated. The Blood Pressure and Oxygenation Targets after Out-of-hospital Cardiac Arrest (BOX) trial, randomized patients to a total duration of device-based fever prevention for 36 or 72 hours. The trial found no differences in mortality or neurologic outcome. Use of device-based fever prevention for a shorter or longer duration could however result in clinically relevant differences in the magnitude of inflammation, vasopressor usage, and oxygen consumption.

AIM: To assess the effect of a shorter or longer duration of device-based fever prevention on inflammation, vasopressor usage, and oxygen consumption in the intervention period from 36 to 72 hours.

METHODS: The BOX trail [NCT03141099] randomized comatose resuscitated out-of-hospital cardiac arrest (OHCA) patients to three different treatment targets in the post-resuscitation phase: mean arterial blood pressure target of 63 or 77mmHg; oxygenation targets of 68-75 or 98-105 mmHg; and duration of device-based fever prevention in comatose patients for a total of 36 or 72 hours. Endpoints at 48 and 72 hours: leukocytes; CRP; vasoactive-inotropic score (VIS); systemic oxygen consumption determined by use of Fick’s principle. Analyses were performed both on the total BOX population, and for a sensitivity analysis, selectively on patients still comatose at 72 hours (i.e., not awake or dead) as these had the most exposure to the intervention.

RESULTS: The total population consists of 789 patients, with 393 and 396 randomized to a total duration of device-based fever prevention for 36 and 72 hours respectively. For the analysis of patients still comatose at 72 hours, 122 and 148 were available for analysis in the 36-hour and 72-hour group respectively. There were no differences between the 36- and 72-hour group for leukocytes, CRP, VIS, or oxygen consumption during the intervention period from 36 until 72 hours, neither for the total population (Figure 1, all p>0.05) or the cohort of patients still comatose at 72 hours (Figure 2, all p>0.05).

CONCLUSIONS: There were no group differences for patients randomized to device-based fever prevention for 36 or 72 hours with respect to the magnitude of inflammation, vasopressor usage, or oxygen consumption. These findings were consistent for the cohort as a whole, and when examining those with most exposure to the intervention.