Mild perioperative hypothermia and the risk of wound infection.

Background: Bacterial destruction caused by free radicals, which are synthesized by neutrophils in the presence of oxygen, depends on adequate tissue perfusion. Mild perioperative hypothermia causes vasoconstriction, reducing nutrient and oxygen supply to wounds and increasing frequency of surgical wound infection. However, the causal role of hypothermia in surgical wound infection is the subject of controversy. The present work proposes the hypothesis that mild perioperative hypothermia is associated with infection of the surgical wound.
Methods: A prospective cohort of 290 surgical patients was studied in a second-level hospital; 261 (90%) of the patients concluded the follow-up. The relationship of hypothermia and of other confounding factors, such as diabetes mellitus, antibiotic treatment, and wound drains with infection outcome was evaluated. One physician, blinded to patient hypothermia, gathered the data. Surgical wound infection was defined as the surgeon's diagnosis with positive culture.
Results: Twenty subjects (7.6%) showed infection of surgical wound; 18 (11.5%) of 156 hypothermics and two (2%) 105 normothermics (p = 0.004). Hypothermia proved to be a significant independent risk of infection with relative risk of 6.3 (p = 0.01).
Conclusions: Mild perioperative hypothermia is associated with infection of the surgical wound and its prevention is therefore justified.