554 (2012)

Introduction: Therapeutic hypothermia improves neurological outcome for comatose survivors of out-of-hospital cardiac arrest. Generally, it is known that faster cooling and stable maintenance of hypothermia result in better outcomes, although there is insufficient clinical evidence. Therefore, the reliable cooling devices are necessary for the effective and safe therapeutic hypothermia. We want to compare the effectiveness and safety of Arctic Sun (AS) and water blanket (WB) during therapeutic hypothermia. Hypothesis: There is no difference between AS and WB regarding the effectiveness and safety during therapeutic hypothermia. Methods: Retrospective analysis was performed in single hospital. Patients who received therapeutic hypothermia after cardiac arrest from January 2010 to May 2012 were identified. Patients who did not complete 24-hour of therapeutic hypothermia were excluded. Demographics and resuscitation factors were abstracted. The time to target temperature (<34?) from the application of cooling was measured to evaluate the effectiveness of cooling method. After the achievement of target temperature, the temperature most remote from 33? was selected every hour. If the selected temperature was not between 32? and 34?, then that hour was considered as violation of maintenance. The rate of violation during maintenance of hypothermia was compared to evaluate the safety of cooling method. In addition, generalized estimation equations (GEE) analysis, which can adjust the correlation among serial temperature of one patient, was used to compare the absolute temperature differences from 33? during maintenance period. All patients were treated by either AS or WB and were continuously monitored using rectal thermometer. Hospital survival and 28-day cerebral performance category score were obtained. Cerebral performance category score 1 and 2 were considered as good neurologic outcome.Statistics: Continuous variables were compared using t-test or GEE. The proportions were compared using Chi square test. P value < 0.05 was considered statistically significant. Stata version 10.1 was used for statistical analysis. Results: AS was used in 23 patients among 53 patients enrolled. Demographics and factors associated with resuscitation did not differ between two groups. Patients discharged alive were more frequent in AS group (73.9% [AS] vs. 43.3% [WB], p=.026). Patients with good neurologic outcome were not different between two groups (26.1% [AS] vs. 16.7% [WB], p=.402). There was no difference between two groups regarding temperature at start of cooling (35.6? [AS] vs. 35.6? [WB], p=.992). Time to target temperature (134.2 min [AS] vs. 233.4 min [WB], p=.056) was lesser in AS group, but it was not statistically significant. Patients with target temperature before 4-hour of cooling (87.0% [AS] vs. 63.3% [WB], p=.053) were not different between two groups. Total maintenance duration (22.7 hr [AS] vs. 21.6 hr [WB], p=.091) was not different between two groups. However, violation of maintenance (2.0% [AS] vs. 23.7% [WB], p<.001) was more frequently observed in WB group. Most violations (103/156 [76.3%]) were hypothermic event (<32?) in WB group. However, all violations were hyperthermic event (>34?) in AS group. The mean absolute temperature differences from 33? during maintenance period were 0.19? (95% CI, 0.17?-0.21?) in AS and 0.76? (95% CI, 0.71?-0.80?) in WB. GEE has revealed that AS decreased this difference by 0.59? (95% CI, 0.44?-0.75?; p<.001) compared to WB. Conclusions: Arctic Sun is superior to water blanket in the maintenance of therapeutic hypothermia. Strict temperature control achieved by Arctic Sun may be useful to minimize unwanted adverse effects of therapeutic hypothermia in cardiac arrest victims.