The association of body mass index with time to target temperature and outcomes following post-arrest targeted temperature management.
BACKGROUND
Evidence suggests that more rapid attainment of target temperature (32-34°C) improves neurologic outcome following cardiac arrest and targeted temperature management (TTM). It is unclear to what extent body mass index (BMI) is associated with the time to reach target temperature and subsequent clinical outcomes.


OBJECTIVE
We sought to determine whether the time to target temperature was affected by BMI. In addition, we wished to determine whether the incidence of skin breakdown, survival to discharge and neurologic outcomes were associated with BMI.


METHODS
Multicenter retrospective cohort study of cardiac arrest patients who underwent TTM between July 2007 and December 2012. We examined the association between BMI and the time from initiation of cooling to attainment of target temperature (32-34°C).


RESULTS
Of 236 patients treated with TTM, 184 were included in the study. Mean age was 57.8±17.0 years; 78/184 (42%) were female and 48/184 (26%) had VF/VT as the initial rhythm. Median time to reach target temperature from ROSC was 6.4 (4.1, 9.8)h and median time from initiation of TTM to target temperature was 3.4 (2.1, 5.8)h. Cooling duration was a median of 24.0 (23.0, 24.0)h and median rewarming time was 12.0 (9.5, 18.0)h. Overall, 104/184 (56.5%) achieved target temperature within 4h and 128/184 (69.6%) within 6h. Increased BMI was associated with a longer time to achieve target temperature from initiation of TTM (p=0.01). There was no significant difference across BMI groups in time to achieve target temperature from ROSC (0.07), skin breakdown (p=0.35), survival (p=0.21), nor rate of good neurologic outcome (p=0.32).


CONCLUSIONS
Target temperature was frequently achieved within 4-6h; as BMI increased, the time to reach target temperature from initiation of TTM was prolonged. There was no significant difference across BMI groups for survival or good neurologic outcome.