Several recent articles about contrast-induced nephropathy (CIN) prompted us to search our now nearly 1000 columns to see what we have written about CIN. Much to our surprise we only found one (see our June 2011 What's New in the Patient Safety World column “Reducing the Risk of Contrast-Related Damage from Imaging Studies”) and that one dealt as much with other contrast-related injuries as it did with CIN.
The study that attracted our attention was one that looked at long-term outcomes in patients who developed CIN (Mitchell 2015). They followed 633 emergency department patients undergoing contrast-enhanced CT, of whom 11% developed acute kidney injury consistent with contrast-induced nephropathy. Within one year 15% experienced at least 1 major adverse event (defined as the combined outcome of death of any cause, renal failure, myocardial infarction, and stroke or other arterial vascular events, in any anatomic territory, requiring invention), including 7% who died. After adjustment for a number of clinical variables the rate of these adverse events was almost 2 and a half times that of patients who did not develop CIN.
Our 2011 column noted many of the risk factors for CIN and mentioned a risk stratification nomogram for predicting CIN in patients undergoing contrast enhanced abdominal CT scans in the emergency room (Kim 2011). But another new study was a systematic review of predictive models that identified patients at risk of contrast induced nephropathy among adults undergoing a diagnostic or interventional procedure using conventional radiocontrast media (media used for computed tomography or angiography, and not gadolinium based contrast) (Silver 2015). Those authors found a total of 12 prediction models but found that ability to predict CIN was modest at best and really only relevant to patients receiving contrast for coronary angiography. The authors conclude that further research is needed to develop models that can better inform patient centered decision making, as well as improve the use of prevention strategies for contrast induced nephropathy.
Pertinent to management, a new study (Qian 2016) addressed prevention of CIN in a particularly high risk group – those patients with chronic kidney disease (CKD) and congestive heart failure (CHF). The incidence of CIN in this group of patients is more than 20%. So the Chinese investigators compared those patients managed with CVP-guided fluid administration vs. those without CVP monitoring in a randomized controlled trial. The incidence of CIN was 15.9% in the group managed with CVP-guided fluid administration vs. 29.5% in the group without CVP monitoring. The former group overall had a higher volume of fluid replacement and higher urinary output. The occurrence of acute heart failure did not differ between the two groups. Since hydration is the cornerstone for prevention of CIN, this study shows that our fears of precipitating acute heart failure or pulmonary edema may be keeping us from optimal fluid management in such patients receiving contrast. It demonstrates that use of CVP monitoring allows for more aggressive fluid management in this high risk group and helps avoid CIN.
While a CVP might allow for more aggressive fluid management, we’ll again note that a simple bedside maneuver may obviate the need for such catheters. Ever since our residency days we’d take great pride in showing our colleagues how a passive leg raise or equivalent can help with decisions about fluid/hemodynamic status in patients, avoiding the need for invasive monitoring.
The Royal College of Physicians also recently made available a toolkit on acute kidney injury and intravenous fluid therapy that includes advice on managing AKI and issues related to contrast (Royal College of Physicians 2015).
Mitchell AM, Kline JA, Jones AE, Tumlin JA. Major Adverse Events One Year after Acute Kidney Injury After Contrast-Enhanced Computed Tomography. Ann Emerg Med 2015; 66(3): p267-274.e4; Published online: May 21 2015
Kim KS, Kim K, Hwang SK, et al. Risk stratification nomogram for nephropathy after abdominal contrast-enhanced computed tomography. The American Journal of Emergency Medicine 2011; 29: 412-417
Silver SA, Shah PM, Chertow GM, et al. Risk prediction models for contrast induced nephropathy: systematic review. BMJ 2015; 351: h4395
Qian G, Fu Z, Guo J, et al. Prevention of Contrast-Induced Nephropathy by Central Venous Pressure–Guided Fluid Administration in Chronic Kidney Disease and Congestive Heart Failure Patients. J Am Coll Cardiol Intv 2016; 9(1): 89-96
Royal College of Physicians. Acute care toolkit 12: Acute kidney injury and intravenous fluid therapy. September 2015
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