January 16, 2020

Background: Computed tomography pulmonary angiography (CTPA) is the current gold standard for diagnosing acute pulmonary embolism in the ED.  It has a high sensitivity, and specificity, is readily available, and can establish analternative diagnoses.  One issue with CTPA is that many hospital protocols create barriers for patients with chronic kidney disease or acute kidney injury (AKI) protocols in place from getting the necessary IV contrast.  There are several studies [2][3][4] that have evaluated the causal relationship between contrast exposure and nephrotoxicity. However, most of these studies are observational and retrospective in nature. The issue with retrospective studies is that they often cannot control for confounders and observational studies cannot give us causation, only association. We now have another retrospective observational study asking the same question, which has the inherent issues of previous studies.