Carbon Dioxide Tolerance in Interstitial and Intravascular Spaces in Dogs

The renewed interest in the adrenal, pancreas, and other retroperitoneal structures stands as a challenge to better diagnostic methods. The outline of the retroperitoneal space has been attempted with small quantities of air or oxygen.^1,2,5,9 However, air embolism following the presacral or flank injection of air or oxygen is being reported with increasing frequency.^3,4,6,8 Use of CO₂ as the agent for retroperitoneal insufflation would have the following advantages: (1) The high solubility of CO₂ would reduce the hazard of gas embolization; (2) CO₂ is free of allergic or idiosyncratic properties, and (3) CO₂ is readily available and is inexpensive. Stauffer, Durant, and Oppenheimer⁷ have safely used CO₂ for delineation of the cardiac chambers in doses of 7.5 cc/kg. In the past six months we have been interested in the investigation of CO₂ as a medium for outlining the retroperitoneal, intraperitoneal, intravascular,