Rapid rewarming after therapeutic hypothermia worsens outcome in sepsis

OBJECTIVE: This study was performed to investigate the effect of the rewarming rate on survival and acute lung injury in sepsis. METHODS: Male Sprague-Dawley rats underwent cecal ligation and incision. After 1 hour of sepsis induction, normothermia (37°C±0.5°C, NT group) or hypothermia (32°C±0.5°C) was induced. Hypothermia was maintained for 4 hours and rats were divided into two groups according to the rewarming rate: RW1 group, 1 hour of rewarming; and RW2 group, 2 hours of rewarming. In the survival study, rats were observed for 12 hours after sepsis induction (n=6 per group). In the second experiment, rats were sacrificed 7 hours after sepsis induction, and lung tissues and plasma were harvested (n=10 per group). RESULTS: In the survival study, the RW2 group survived longer than the RW1 group (P<0.05), but the RW1 and NT groups showed no significant difference in survival duration (P>0.05). The histological lung injury score and malondialdehyde concentrations in the lung tissues were significantly higher in the RW1 group than in the RW2 group (P<0.05). Plasma interleukin (IL)-6 concentration and the ratio of IL-6 to IL-10 were higher in the RW1 group than in the RW2 group (P<0.05). CONCLUSION: Rapid rewarming after therapeutic hypothermia results in a shorter survival period and acute lung injury in sepsis, which could be associated with the inflammatory responses.