Arterial blood pressure during targeted temperature management after out-of-hospital cardiac arrest and association with brain injury and long-term cognitive function

Objectives: During targeted temperature management after out-of-hospital cardiac arrest infusion of vasoactive drugs is often needed to ensure cerebral perfusion pressure. This study investigated mean arterial pressure after out-of-hospital cardiac arrest and the association with brain injury and long-term cognitive function. Methods: Post-hoc analysis of patients surviving at least 48 hours in the biobank substudy of the targeted temperature management trial with available blood pressure data. Patients were stratified in three groups according to mean arterial pressure during targeted temperature management (4-28 hours after admission; <70 mmHg, 70-80 mmHg, >80 mmHg). A biomarker of brain injury, neuron-specific enolase, was measured and impaired cognitive function was defined as a mini-mental state examination score below 27 in 6-month survivors. Results: Of the 657 patients included in the present analysis, 154 (23%) had mean arterial pressure less than 70 mmHg, 288 (44%) had mean arterial pressure between 70 and 80 mmHg and 215 (33%) had mean arterial pressure greater than 80 mmHg. There were no statistically significant differences in survival (P=0.35) or neuron-specific enolase levels (P=0.12) between the groups. The level of target temperature did not statistically significantly interact with mean arterial pressure regarding neuron-specific enolase (P-interaction_MAP*TTM=0.58). In the subgroup of survivors with impaired cognitive function (n=132) (35%) mean arterial pressure during targeted temperature management was significantly higher (P-group=0.03). Conclusions: In a large cohort of comatose out-of-hospital cardiac arrest patients, low mean arterial pressure during targeted temperature management was not associated with higher neuron-specific enolase regardless of the level of target temperature (33 degrees C or 36 degrees C for 24 hours). In survivors with impaired cognitive function, mean arterial pressure during targeted temperature management was significantly higher.