Time to awakening after cardiac arrest and the association with target temperature management

Abstract

Aim: Target temperature management (TTM) at 32-36 °C is recommended in unconscious survivors of cardiac arrest. This study reports awakening in the TTM-trial. Our predefined hypotheses were that time until awakening correlates with long-term neurological outcome and is not affected by level of TTM.

Methods: Post-hoc analysis of time until awakening after cardiac arrest, its association with long-term (180-days) neurological outcome and predictors of late awakening (day 5 or later). The trial randomized 939 comatose survivors to TTM at 33 °C or 36 °C with strict criteria for withdrawal of life-sustaining therapies. Administered sedation in the treatment groups was compared. Awakening was defined as a Glasgow Coma Scale motor score 6.

Results: 496 patients had registered day of awakening in the ICU, another 43 awoke after ICU discharge. Good neurological outcome was more common in early (275/308, 89%) vs late awakening (142/188, 76%), p < 0.001. Awakening occurred later in TTM33 than in TTM36 (p = 0.002) with no difference in neurological outcome, or cumulative doses of sedative drugs at 12, 24 or 48 h. TTM33 (p = 0.006), clinical seizures (p = 0.004), and lower GCS-M on admission (p = 0.03) were independent predictors of late awakening.

Conclusion: Late awakening is common and often has a good neurological outcome. Time to awakening was longer in TTM33 than in TTM36, this difference could not be attributed to differences in sedative drugs administered during the first 48 h.

Keywords: Awakening; Cardiac arrest; Sedation; Target temperature management; Withdrawal.