Purpose: The authors examined the nephrotoxicity of carbon dioxide injected directly into the renal arteries as an arterial contrast agent.
Materials and methods: Fourteen anesthetized dogs received selective renal infusions of CO2 ranging from a normal dose of 7 cm3/kg to high doses of 11-54 cm3/kg. Two dogs received conventional iodinated contrast media. The effects on renal function and histologic appearance were evaluated by means of radionuclide studies (iodine-131 iodohippurate sodium and technetium-99m dimercaptosuccinate) and histopathologic examination (light, transmission, and scanning electron microscopy).
Results: Although there was a mean decrease in renal blood flow of 11.86% (standard error [SE], 7.1) immediately after the injection of CO2, flow had returned to baseline (0.17%; SE, 5.27) after 24 hours. Although the sample size was small, there was no dose-dependent effect of CO2 on renal function and histologic appearance. Mild histologic changes and one case of moderate acute tubular necrosis were seen only in cases in which the kidney was positioned vertically rather than laterally.
Conclusion: Although formal studies in patients are required, the results of this investigation suggest that CO2 may be a safe contrast agent and less nephrotoxic than existing contrast agents, providing care is taken to ensure that CO2 is not trapped in a vertically positioned kidney, as might occur in renal transplant recipients.