Intra-Operative Tissue Oxygen Tension Is Increased by Local Insufflation of Humidified-Warm CO(2) during Open Abdominal Surgery in a Rat Model

INTRODUCTION: Maintenance of high tissue oxygenation (PtO(2)) is recommended during surgery because PtO(2) is highly predictive of surgical site infection and colonic anastomotic leakage. However, surgical site perfusion is often sub-optimal, creating an obstructive hurdle for traditional, systemically applied therapies to maintain or increase surgical site PtO(2.) This research tested the hypothesis that insufflation of humidified-warm CO(2) into the abdominal cavity would increase sub-peritoneal PtO(2) during open abdominal surgery. MATERIALS AND METHODS: 15 Wistar rats underwent laparotomy under general anesthesia. Three sets of randomized cross-over experiments were conducted in which the abdominal cavity was subjected to alternating exposure to 1) humidified-warm CO(2) & ambient air; 2) humidified-warm CO(2) & dry-cold CO(2); and 3) dry-cold CO(2) & ambient air. Sub-peritoneal PtO(2) and tissue temperature were measured with a polarographic oxygen probe. RESULTS: Upon insufflation of humidified-warm CO(2), PtO(2) increased by 29.8 mmHg (SD 13.3; p<0.001), or 96.6% (SD 51.9), and tissue temperature by 3.0°C (SD 1.7 p<0.001), in comparison with exposure to ambient air. Smaller, but significant, increases in PtO(2) were seen in experiments 2 and 3. Tissue temperature decreased upon exposure to dry-cold CO(2) compared with ambient air (-1.4°C, SD 0.5, p = 0.001). CONCLUSIONS: In a rat model, insufflation of humidified-warm CO(2) into the abdominal cavity during open abdominal surgery causes an immediate and potentially clinically significant increase in PtO(2). The effect is an additive result of the delivery of CO(2) and avoidance of evaporative cooling via the delivery of the CO(2) gas humidified at body temperature.