['Sternal wound dehiscence and infection complicate 1% of cardiac surgeries. Tissue oxygen tension (PsqO(2)) is the primary determinant of surgical wound infection risk and is often critically low in surgical incisions. We tested the hypothesis that local transdermal delivery of oxygen improves oxygenation in sternotomy wounds after cardiac surgery. Our secondary hypothesis was that supplemental inspired oxygen improves sternal wound PsqO(2).', 'After undergoing cardiopulmonary bypass, 30 patients randomly received (1) 2 EpiFlo oxygen generators (Ogenix, Inc., Beachwood, OH) that provided oxygen at 6 mL/h into an occlusive wound dressing or (2) identical-appearing inactive generators. PsqO(2) and temperature were measured in the wound approximately 5 mm below the skin surface. PsqO(2) and arterial oxygen (Pao(2)) were measured 1 h after intensive care unit admission (Fio(2) = 60%) and on the first and second postoperative mornings at Fio(2) of both 30% and 50% in random order.', 'Data from four patients were excluded for technical reasons. Patient characteristics were similar in each group, as were type of surgery and perioperative management. Increasing Fio(2) from 30% to 50% improved Pao(2) from 99 [84-116] to 149 [128-174] mm Hg (P < 0.001, mean [95% CI]) and sternal wound PsqO(2) from 23 [16-33] to 27 [19-38] mm Hg (P < 0.001). In contrast, local oxygen delivery did not improve tissue oxygenation: 24 [14-41] vs 25 [16-41] mm Hg (P = 0.88).'] Does transdermal oxygen improve sternal wound oxygenation in patients recovering from cardiac surgery?