Use of hypothermia for out-of-hospital cardiac arrest survivors: a single-centre experience

Introduction

Out-of-hospital cardiac arrest patients have a poor prognosis. Recent randomised controlled trials have shown that moderate hypothermia improves neurologic outcome and survival in selected patients after cardiac arrest [1]. Therapeutic hypothermia is now recommended by the ALS Task Force of the ILCOR and incorporated in the American and European resuscitation guidelines for postresuscitation care.

Methods

Case notes of all OHCA patients admitted alive to our ICU in 2006 were retrospectively analysed. All patients received standard care including adequate sedation and mechanical ventilation. Mild hypothermia was initiated as soon as possible and ideally maintained at 32–34°C for 12–24 hours with a combination of cold saline, cooling blanket and ice packs. Patients were allowed to passively rewarm. The institution's ethics committee approved the study. Discharged survivors were followed up for 6 months, and neurologic outcome was evaluated using the Glasgow Outcome Score (GOS).

Results

Twenty-five patients were admitted following OHCA. Twenty (80%) fulfilled our cooling criteria. Eight patients had cooling initiated in A&E whereas nine had cooling initiated in the ICU and three were not cooled. Five patients were at target temperature on arrival in A&E. Of the 17 patients who had cooling initiated in hospital, the target temperature was achieved in only 15 patients. In patients where cooling was initiated in A&E, the median time to reach the target temperature from hospital admission was 4.25 hours; and when cooling was initiated in the ICU, it was 6.25 hours. A temperature above 37.5°C was noted in 12 (48%) patients during rewarming. Seven (28%) had a favourable outcome and were discharged from the hospital with a GCS of 15 and all had a GOS of 5 at 6 months. Five out of seven survivors were cooled. The cause of death was hypoxic brain injury in 15 (60%) and cardiogenic shock in three (12%) patients. All deaths occurred in hospital following treatment limitation decisions at (median (range)) 41 (9.5–94) hours.

Conclusion

Our mortality rate of 72% was higher than the HACA study but the same as the Intensive Care National Audit and Research Centre. All survivors had a good neurologic outcome. Using this method of cooling we failed to achieve consistent hypothermia. Preventing rebound hyperthermia was difficult and many treatment limitation decisions were made before 72 hours.