Hypothermia during laparotomy can be prevented by locally applied warm water and pulsating negative pressure

Conflicting results have been obtained when using heat and constant negative pressure applied to the arm to induce re-warming in patients with mild hypothermia due to surgery. We hypothesized that pulsating negative pressure would increase skin blood flow and thus heat transfer. The purpose of this study was to compare a new method of applying heat and pulsating negative pressure to the skin with conventional forced-air warming for preventing perioperative hypothermia.

Twenty patients undergoing prolonged laparotomy for gastric surgery were randomized into two groups. One group (SM) received hospital standard method: forced-air warming, 43 degrees C (Bair Hugger) on the thoracic and upper arm surface. The other group (NM) received the new method: warm water and pulsating negative pressure treatment applied in a transparent acrylic cylinder (50 x 16 cm) on one arm. The cylinder was circulated with water at 42.5 degrees C, leaving an air pocket inside the device. Pulsating pressure between 0 and -40 mm Hg was generated in the air pocket inside the cylinder.

Two groups of 10 patients were studied. Warming was started shortly after induction of general anaesthesia. The two methods performed similarly during the first 60 min, with a mean 0.7 degrees decrease in core temperature. The tympanic temperature curve in NM group then increased and returned to baseline (37 degrees C) by 120 min. The temperature of SM group increased more slowly, reaching 36 degrees C by 120 min (P < 0.05).

Warm water and pulsating negative pressure was significantly better at treating hypothermia during laparotomy than forced-air warming.