Seasonal variability and influence of outdoor temperature on body temperature of cardiac arrest victims.

Aim of the study: Mild therapeutic hypothermia is a major advance in post-resuscitation-care. Some questions remain unclear regarding the time to initiate cooling and the time to achieve target temperature below 34 degrees C. We examined whether seasonal variability of outside temperature influences the body temperature of cardiac arrest victims, and if this might have an effect on outcome. Methods: Patients with witnessed out-of-hospital cardiac arrests were enrolled retrospectively. Temperature variables from 4 climatic stations in Vienna were provided from the Central Institute for Meteorology and Geodynamics. Depending on the outside temperature at the scene the study participants were assigned to a seasonal group. To compare the seasonal groups a Student's t-test or Mann-Whitney U test was performed as appropriate. Results: Of 134 patients, 61 suffered their cardiac arrest during winter, with an outside temperature below 10 degrees C; in 39 patients the event occurred during summer, with an outside temperature above 20 degrees C. Comparing the tympanic temperature recorded at hospital admission, the median of 36 degrees C (IQR 35.3-36.3) during summer differed significantly to winter with a median of 34.9 degrees C (IQR 34-35.6) (p < 0.05). This seasonal alterations in core body temperature had no impact on the time-to-target-temperature, survival rate or neurologic recovery. Conclusion: The seasonal variability of outside temperature influences body temperature of out-of-hospital cardiac arrest victims. (C) 2012 Elsevier Ireland Ltd. All rights reserved.