We performed a retrospective analysis of patients cooled to 32–34 °C during 24 h after CA, who regained neurological responsiveness after rewarming. We measured the time until awakening, defined as obedience to verbal commands.
We included 163 CA survivors (84.7% male, 60.2 years) who regained consciousness after TTM: target temperature was either 32 °C (36.2%), 33 °C (56.4%) or 34 °C (6.7%). Mean time of awakening was 3.8 days. Thirty-four patients (20.9%) regained neurological responsiveness after 5 days after CA. All of them had been cooled to either 32 °C (18 patients) or 33 °C (16), and no patient cooled to 34 °C awakened after day 5. A lower target temperature was associated with a later awakening (p < 0.001). The time to advanced cardiopulmonary resuscitation (CPR) was shorter among the early awakers (p = 0.04), but we found no other predictors of an earlier awakening.
A high proportion of CA survivors induced to TTM regained consciousness after 5 days, and cooling to a lower target temperature may influence on a late neurological recovery. Therefore, withdrawal of life supporting treatment should be delayed to more than 5 days in patients cooled to 33 °C or less. Time to advanced CPR was found to be a predictor of early awakening.