A Simple DSA Method to Detect Air Contamination During CO₂ Venous Studies

Abstract

The use of CO₂ as a contrast agent has increased significantly for visualization of the central veins, inferior vena cava, and portal vein. The most serious complication associated with CO₂ studies is air contamination. We evaluated a simple digital subtraction angiogram (DSA) method to detect air contamination during CO₂ venous studies. After injections of 5, 10, and 20 cm³ of CO₂ and 5 cm³ of air into the inferior vena cavas of five domestic swine in the left lateral decubitus position, a DSA was performed using the cross-table lateral projection to visualize the gases trapped in the right atrium. The time to complete dissolution of CO₂ at increased doses was compared to that of air. Vital signs were observed during and after CO₂ or air injection. In all animals, DSA showed the trapped gas outlining the wall of the right atrium. Five cubic centimeters of CO₂ was cleared from the right atrium in an average of 46 sec (21–60 sec), whereas 5 cm³ of air remained visible over 5 min. Ascending doses of CO₂ increased the time of dissolution to 54 sec (47–67 sec) for 10 cm³ and 70 sec (45–90 sec) for 45 cm³. Vital signs remained stable during the study. Using DSA, CO₂ can be distinguished from air by demonstrating rapid absorption of the former, thus allowing detection of air contamination during CO₂ venous studies. If the gases trapped in the right atrium remain visible 90 sec after the injection, air contamination should be suspected.