Local wound heating improves tissue oxygen tension in postoperative patients.
Forty normothermic and well-hydrated patients recovering from elective open abdominal surgery.
A comparison between an experimental bandage system (Warm-Up; Augustine Medical Inc, Eden Prairie, Minn) and conventional gauze covered with elastic adhesive (Medipore Dress-it; 3M, St Paul, Minn). The experimental system is heated to 38°C and does not touch the wound.
Main Outcome Measures
Subcutaneous tissue oxygen tension was measured postoperatively and on the first postoperative day. In a subgroup, we also evaluated the effects of bandage pressure per se on tissue oxygen.
Initial postoperative tissue oxygen tensions were approximately 30 mm Hg greater with the experimental bandage, even before warming. Subcutaneous oxygen tension during heating remained significantly greater in patients with the warmed bandage than the conventional elastic bandage (116±40 vs 85±34 mm Hg, respectively) while the patients were breathing approximately 50% oxygen. The difference was smaller on the first postoperative day, but still statistically significant (82±30 vs 65±22 mm Hg, respectively). In the subgroup analysis, tissue oxygen tension increased significantly by 12±4 mm Hg when the heating bandage was substituted for a conventional bandage (P<.001).
In normothermic and well-hydrated surgical patients, much benefit from the heating bandage system appears to result from pressure relief. These data suggest that relieving wound pressure markedly improves tissue perfusion and oxygenation.