PURPOSE: To evaluate the safety and usefulness of carbon dioxide (CO2) as a venous contrast agent for upper-arm placement of peripherally inserted central venous catheter (PICC), vena caval filter placement, and for visualization of the portal vein in transjugular intrahepatic portosystemic shunt (TIPS). MATERIALS AND METHODS: About 20-30ml of CO2 was used as an alternative to iodinated contrast material for digital subtraction angiography (DSA) and fluoroscopy to guide upper-arm placement of PICC in 46 patients, for inferior venacavogram before filter placement in five, and for visualization of the portal vein during TIPS in two. Vital signs, peripheral arterial oxygen saturation, and renal function were checked during and after delivery of CO2. RESULTS: All CO2 DSA for PICC placement clearly delineated patency or stenosis of the central veins. In 41 of 46 patients (89%), PICC placement with CO2 guidance was successful. The mean number of venipunctures for PICC placement was 1.9, and the mean volume of CO2 injected for venipuncture was 35 ml. In five patients, Titanium Greenfield filters were successfully implanted into the inferior vena cava following CO2 vena cavography. In two patients in whom hepatopetal portal flow was seen on indirect portography, the portal vein was visualized by CO2-wedged hepatic venography. Injection of CO2 into the splenic vein following TIPS placement revealed shunt patency. Vital signs and oxygen saturation did not change, and there was no evidence of renal toxicity following CO2 injection. CONCLUSION: CO2 is a safe and useful alternative contrast agent for upper-arm placement of PICC, pre-filter placement cavography, and wedged hepatic venography and portography for TIPS.