Inhaled isoflurane sedation during therapeutic hypothermia after cardiac arrest: a case series.

ABSTRACT

OBJECTIVE: Therapeutic hypothermia in the ICU requires mechanical ventilation and sedation. Hypothermia reduces the metabolism of commonly used IV sedatives. The use of long-acting sedative agents may confound neurologic assessment. Volatile anesthetics have been reported to provide protection against ischemia-reperfusion injury and have been safely used in the ICU to provide sedation in trials with shorter wake-up times. There are no clinical studies in this setting. We describe a case series and discuss potential benefits. DESIGN: Retrospective study. SETTINGS Ten-bed ICU, university hospital. PATIENTS Twelve patients resuscitated from cardiac arrest with Glasgow Coma Scale score less than or equal to 4. INTERVENTION Isoflurane sedation with the AnaConDa during 24 hours therapeutic hypothermia, until rewarming. MEASUREMENTS AND MAIN RESULTS: Data were extracted from the computerized ICU chart/monitors, hospital and prehospital charts, and the national death index. Patients were 49-76 years old. Median return of spontaneous circulation was 14 minutes. Glasgow Coma Scale scores were assessed within 24 hours from reaching normal body temperature and compared with outcomes at 6 months six patients had poor Glasgow Coma Scale scores (< 8) that remained low and all died before 6-month follow-up, whereas another six patients had high scores (> 8) and survived to 6 months with good Cerebral Performance Category. In the ICU, four of the survivors were directly extubated after rewarming while two were once more sedated due to pneumonia requiring invasive ventilator therapy. All patients required norepinephrine to maintain adequate mean arterial pressure. Isoflurane sedation was changed to midazolam in two nonsurviving patients because of hemodynamic instability, which persisted despite the change. CONCLUSIONS: Sedation with volatile anesthetics during therapeutic hypothermia may be a feasible short-acting option with potential postconditioning effects protecting vital organs from ischemia-reperfusion injury. Its measurability and insignificant drug accumulation could facilitate early neurologic assessment. Prospective clinical trials are warranted.