Efficacy of Forced-Air Warming to Prevent Perioperative Hypothermia in Morbidly-Obese Versus Non-obese Patients.

Background: Hypothermia is associated with an increased postoperative morbidity and mortality. Forced-air warming systems are the most effective methods for its prevention. When using a mattress, a reduction in the area of diffusion of warm air by crushing due to excess weight cannot be ruled out.

Methods: We designed a prospective study to compare the efficacy of a forced-air warming mattress (Bair Hugger® 585) to prevent hypothermia (core temperature (CT°) < 36 °C) in morbidly obese (group MO, body mass index (BMI) ≥ 40 kg/m) and non-obese patients (group NO, BMI < 30 kg/m).

Results: Twenty-six patients were included in group MO (84% bariatric surgery, 96% laparoscopic procedures) and 32 in group NO (37.5% cholecystectomy, 62.5% laparoscopic procedures). The incidence of hypothermia was not different between the two groups 1 h after induction (H1) and at extubation: 22 vs 19% (not significant (NS)) and 23 vs 19% (NS) for the group MO versus group NO. At H1, the mean CT° was not different: 36.3 ± 0.4 °C vs 36.4 ± 0.5 °C (NS), group MO versus group NO. No patient presented severe hypothermia (CT° < 34.9 °C). Dysfunction of the forced-air warming mattress was observed for eight patients (31%) in group MO but for none in group NO.

Conclusion: The forced-air warming mattress is effective in preventing hypothermia in MO patients. However, excess weight is associated with frequent dysfunction of the system, which does not make it a practical system in a context of MO.