Time to Awakening Is Often Delayed in Patients Who Receive Targeted Temperature Management After Cardiac Arrest

Post cardiac arrest, neuroprognostication remains a complex and clinically challenging issue for critical care providers. For this reason, our primary objective in this study was to determine the frequency of survival and favorable neurological outcomes in post-cardiac arrest patients with delayed time to awakening. To assess whether early withdrawal of care may adversely impact survival, we also sought to describe the time to withdrawal of care of non-surviving patients. We performed a retrospective study of patients resuscitated after cardiac arrest in two large academic community hospitals. We performed a structured chart review of patients treated with therapeutic hypothermia (TH) at one hospital from 2009 to 2015 and at a second hospital from 2013 to 2015. Demographics and Utstein style variables were recorded on all patients, as well as temporal variables to characterize the time interval from Return of Spontaneous Circulation (ROSC) to awakening as recorded by ICU nurses and defined as Glasgow Coma Scale (GCS) of >8. Descriptive data were also captured regarding time to withdrawal of care. We pre-hoc defined delayed awakening as >72 hours post ROSC or >72 hours post rewarming. Our primary outcome was survival to hospital discharge with a secondary outcome of a favorable cerebral performance category of 1 or 2. During this study period, 321 patients received TH, with 111 (34.6%) discharged alive and, of these, 67 (68.5%) experienced a good neurological outcome. Awakening more than 72 hours after return of circulation was common with 31 patients surviving to discharge. Of these, 16 of 31 (51.6%) were found to have a good neurological outcome on hospital discharge. Of the patients who died before discharge, 54 (29.5%) had care withdrawn less than 72 hours after ROSC. A delayed time to awakening is not infrequently associated with a good neurological outcome after TH in patients resuscitated from cardiac arrest.