EFFECT OF SUBCUTANEOUS CARBON-DIOXIDE INSUFFLATION ON ARTERIAL PCO(2)

PURPOSE: Subcutaneous emphysema following laparoscopy could result in postoperative respiratory acidosis from prolonged CO2 absorption, We s tudied the magnitude and duration of alterations in PaCO2 coincident w ith direct CO2 insufflation into the subcutaneous fat of the anterior abdominal wall of 5 anesthetized juvenile pigs. METHODS: First, each p ig was insufflated with 6 L of CO2 to produce moderate emphysema over the trunk, Following return to baseline PaCO,, each pig was re-insuffl ated with 12 L of CO2 to produce severe emphysema over lower limbs, ne ck, head, and trunk, Measurements of arterial blood gases were perform ed every 5 or 10 min, Minute ventilation was held constant to represen t the worst case scenario. RESULTS: From baseline PaCO2 of 41.8 +/- 2. 3 mm Hg, PaCO2 peaked at 68.3 +/- 8.6 (P < 0.02) and 92.9 +/- 10.7 (P < 0.01) mm Hg for the 6- and 12-L volumes, respectively, 20 to 25 minu tes following insufflation. Front baseline arterial pH of 7.40 +/- 0.0 2, respective nadirs of pH were 7.21 +/- 0.06 (P < 0.02) and 7.08 +/- 0.05 (P < 0.01). PaCO2 and arterial pH took approximately 100 minutes to return to baseline after insufflation with both 6 and 12 L volumes CONCLUSIONS: When minute ventilation is fixed, subcutaneous CO2 insuff lation causes increased PaCO2 and decreased pH that may persist for a prolonged period of time, Therefore, patients with subcutaneous emphys ema after laparoscopy should be observed in postanesthetic recovery un til PaCO2 and pH approach baseline.