Maintenance of subcutaneous cavities with CO2

Since mechanical retractors in endoscopic plastic surgery cause certain drawbacks, we developed a model in dogs, which, by insufflating CO2 into a subcutaneous cavity, we were able to maintain. We evaluated the magnitude of subcutaneous emphysema and absorption of CO2 by insufflating different pressures and the efficacy of external pressure on the skin with the purpose of limiting the subcutaneous emphysema. Sixteen dogs were divided in 3 groups, A, B, and C. We controlled the pulmonary function by using a volume-cycle ventilator. In all groups, we maintained a subcutaneous cavity by insufflating CO2. Groups A and C were insufflated at 15 mm Hg; group B, at 8 mm Hg. We placed circumferential Esmarch bandages on the thorax of groups B and C to delimit superiorly and inferiorly the surgical area. Arterial blood gas analyses (ABGA) were taken from the femoral artery 60 minutes after intubation, 60 minutes after Esmarch bandage was placed and at the end of the CO2 insufflation. Statistically, results were analyzed by Wilcoxon test. P < 0.05 was considered statistically significant. Group A showed extensive subcutaneous emphysema. Two dogs died. The systemic increase of the CO2 showed a median of 9.6 mm Hg (P < 0.05). In Group B, Esmarch bandages caused increase in CO2, with a median of 1.65 mm Hg (P < 0.028). None of these dogs showed subcutaneous emphysema during the insufflation after CO2 insufflation pressure augmented with a median of 3.7 mm Hg (P < 0.028). In Group C, chest restriction increased CO2 median of 6.1 mm Hg (P < 0.043), and subcutaneous emphysema shown was less extensive than group A. The CO2 increased after insufflation a median of 16 mm Hg (P < 0.043). CONCLUSIONS: Subcutaneous cavities can be maintained open with CO2 insufflation at 8 mm Hg, limiting perfectly the surgical area; as done with Esmarch bandages, it reduces CO2 absorption and makes this procedure safe.