Awakening after cardiac arrest and post resuscitation hypothermia: are we pulling the plug too early?
BACKGROUND
Time to awakening after out-of-hospital cardiac arrest (OHCA) and post-resuscitation therapeutic hypothermia (TH) varies widely. We examined the time interval from when comatose OHCA patients were rewarmed to 37°C to when they showed definitive signs of neurological recovery and tried to identify potential predictors of awakening.


METHODS
With IRB approval, a retrospective case study was performed in OHCA patients who were comatose upon presentation to a community hospital during 2006-2010. They were treated with TH (target of 33°C) for 24h, rewarmed, and discharged alive. Comatose patients were generally treated medically after TH for at least 48h before any decision to withdraw supportive care was made. Pre-hospital TH was not used. Data are expressed as medians and interquartile range.


RESULTS
The 89 patients treated with TH in this analysis were divided into three groups based upon the time between rewarming to 37°C and regaining consciousness. The 69 patients that regained consciousness in ≤48h after rewarming were termed "early-awakeners". Ten patients regained consciousness 48-72h after rewarming and were termed "intermediate-awakeners". Ten patients remained comatose and apneic >72h after rewarming but eventually regained consciousness; they were termed "late-awakeners". The ages for the early, intermediate and late awakeners were 56 [49,65], 62 [48,74], and 58 [55,65] years, respectively. Nearly 67% were male. Following rewarming, the time required to regain consciousness for the early, intermediate and late awakeners was 9 [2,18] (range 0-47), 60.5 [56,64.5] (range 49-71), and 126 [104,151]h (range 73-259), respectively. Within 90 days of hospital admission, favorable neurological function based on a Cerebral Performance Category (CPC) score of 1 or 2 was reported in 67/69 early, 10/10 intermediate, and 8/10 late awakeners.


CONCLUSIONS
Following OHCA and TH, arbitrary withdrawal of life support <48h after rewarming may prematurely terminate life in many patients with the potential for full neurological recovery. Additional clinical markers that correlate with late awakening are needed to better determine when withdrawal of support is appropriate in OHCA patients who remain comatose >48h after rewarming.
Department of Anesthesiology, Universersity of Minnesota, United States. Electronic address: GoldX002@umn.edu.
Barbara
B
Gold
Department of Emergency Medicine at Hennepin County Medical Center, Minneapolis, MN, United States.
Laura
L
Puertas
Department of Medicine, St. Cloud Hospital, United States.
Scott P
SP
Davis
Department of Emergency Medicine at Hennepin County Medical Center, Minneapolis, MN, United States.
Anja
A
Metzger
Department of Internal Medicine, University of Minnesota, United States.
Demetris
D
Yannopoulos
Department of Medicine, St. Cloud Hospital, United States.
Dana A
DA
Oakes
Take Heart Minnesota, United States.
Charles J
CJ
Lick
Take Heart Minnesota, United States.
Debbie L
DL
Gillquist
Take Heart Minnesota, United States.
Susie Y Osaki
SY
Holm
Department of Medicine, St. Cloud Hospital, United States.
John D
JD
Olsen
Department of Medicine, St. Cloud Hospital, United States.
Sandeep
S
Jain
Department of Medicine, St. Cloud Hospital, United States; Take Heart Minnesota, United States; Department of Internal Medicine, University of Minnesota, United States; Department of Emergency Medicine at Hennepin County Medical Center, Minneapolis, MN, United States.
Keith G
KG
Lurie
D000368:Aged; D016887:Cardiopulmonary Resuscitation; D003128:Coma / Q000503:physiopathology; D005260:Female; D006801:Humans; D007036:Hypothermia, Induced; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D058687:Out-of-Hospital Cardiac Arrest / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*; D020127:Recovery of Function; D012189:Retrospective Studies; D017694:Rewarming; D015996:Survival Rate; D016896:Treatment Outcome; D014851:Wakefulness / Q000502:physiology*; D028761:Withholding Treatment
Cardiac arrest; Cerebral Performance Category; Comatose; Hypothermia; Life support