{'fraction_non_alphanumeric': 0.021696252465483234, 'fraction_numerical': 0.018878557340095803, 'mean_word_length': 4.996621621621622, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Commentary: Carbon Dioxide Automated Angiography in Patients With a High Risk of Contrast-Induced Nephropathy Who Undergo Percutaneous Interventions for Critical Limb Ischemia

Carbon dioxide (CO 2 ) angiography is a diagnostic radiologic procedure introduced about 50 years ago to obtain vascular images without the use of iodinated contrast medium (ICM). Nevertheless, some procedural aspects of CO 2 angiography remain unsettled. In most cases, a manual injection is used, and expert operators state that a long period of empirical training is required to obtain good quality images. This is because it is necessary to acquire the skill to control the manual injection and to use the natural properties of CO 2 (buoyancy) in order to optimally fill the vessel with the gas. The operative learning process is mainly based on observation of the images obtained and the effects of changes in manual operations. How the gas is injected under the different operative conditions is a consequence of previous positive and negative experiences; a knowledge of the mechanical behavior of the gas in the vascular cavity is assumed not to be important. The problem of injection control has mainly been tackled by controlling the pressure. While automatic injectors have been proposed, manual injection remains the most common technique even in very complex procedures. In this issue of the JEVT, Palena et al tested the safety, efficacy, and diagnostic accuracy of automated CO 2 angiography (ACDA) for the evaluation of diabetic patients with critical limb ischemia (CLI) and baseline chronic renal insufficiency [chronic kidney disease (CKD)] in order to compare ACDA with ICM during endovascular interventions. They concluded that ACDA is an accurate, safe, and effective technique than can be used to guide endovascular interventions in diabetic CLI patients with baseline CKD. They did not find significant changes in the estimated glomerular filtration rate from baseline to 24 hours, and the diagnostic accuracy of CO 2 was very high (89.8%) and very similar to the accuracy of ICM angiography. In the past, many interventionists expressed concern about the suitability of using CO 2 imaging in the lower extremities, particularly in smaller below-the-knee (BTK) vessels. Several studies have reported the use of CO 2 as an alternative to ICM, with good diagnostic quality in lower limb arteries located above the knee (ATK). In a study by Rolland et al, the imaging quality of CO 2 angiography was equivalent to ICM angiography at the pelvis in 93% and at the thigh in 74% of 120 arteries studied. The same quality was achieved distally in only half of the cases. Oliva et al found no significant differences in the mean stenosis values obtained with CO 2 or ICM in any segment for any of the observers; however, such favorable results have not been demonstrated when imaging BTK vessels using CO 2 . In a recent series, CO 2 angiography showed a diagnostic accuracy of 97.1% in the ATK district and 96.7% in the BTK district. There are several reasons for these different results: the prevalence of patients with complete occlusion of the proximal vessels, the site of the CO 2 injection, the CO 2 delivery system employed, and the use of CO 2 -dedicated postprocessing software. As some investigators indicated, the unsatisfactory opacification of the BTK vessels by CO 2 could be related to the high prevalence of patients with complete occlusion of 620870 JETXXX10.1177/1526602815620870Journal of Endovascular TherapyScalise research-article2015