Subcutaneous tissue oxygen tension after coronary revascularisation with and without cardiopulmonary bypass

Directly measured subcutaneous tissue oxygen tension reflects the adequacy of regional tissue oxygenation and influences wound infection and healing. We tested the hypothesis that off-pump coronary artery bypass would increase subcutaneous tissue oxygen tension by minimizing cardiopulmonary bypass-induced systemic inflammation. Ten consecutive patients scheduled for off-pump coronary artery bypass were compared with 10 undergoing conventional cardiopulmonary bypass. All patients had a tissue oxygen sensor implanted longitudinally into the subcutaneous tissue of the leg in the saphenous vein harvest wound. Data were collected from closure of the saphenous vein wound for 20 h postoperatively. Although more off-pump patients had only one coronary artery grafted, postoperative subcutaneous tissue oxygen tension was significantly higher in off-pump patients throughout the 20-h study. Absolute mean (SD) differences ranged from 2.3 kPa in the first 2 h [14.4 (2.3) vs. 12.1 (2.4) kPa in off-pump and cardiopulmonary bypass, respectively, p = 0.04] to 4.6 kPa at 8-10 h [14.0 (3.5) vs. 9.3 (2.7) kPa, p = 0.007]. In contrast, there were no significant differences in arterial oxygen tension values over this period. Mean arterial pressure and haemoglobin were transiently higher in off-pump patients at 8 h only. We conclude that postoperative subcutaneous tissue oxygen tension was higher for 20 h after off-pump compared with conventional cardiopulmonary bypass.