Preventing Contrast-Induced Nephropathy in the Emergency Department

Christopher I. Doty, MD

Disclosures

March 29, 2010

Question

Are intravenous fluids useful in the prevention of contrast-induced nephropathy in the emergency department?

Response from Christopher I. Doty, MD
Assistant Professor of Emergency Medicine, Residency Director, SUNY Downstate Medical Center, Brooklyn, New York

Contrast-induced nephropathy (CIN) is the third leading cause of hospital-acquired acute renal failure in the United States, accounting for 10% of all cases of hospital-acquired renal failure. The increasing use of intravenous (IV) contrast-enhanced imaging exposes an expanding number of patients to this potential complication. Several studies have examined the prevention of CIN, but few address the unique time limitations that physicians in the emergency department face in treating patients.

Although CIN is generally limited to a transient decline of renal function, it is not a benign complication. Some degree of residual renal impairment has been reported in as many as 30% of patients affected by CIN, and CIN has been associated with prolonged hospital stays, higher medical costs, and increased in-hospital and long-term mortality. Therefore, decreasing the incidence of CIN in our patients should be a goal of all emergency physicians.

Most of the published studies have focused on protocols involving pretreatment and often posttreatment for invasive cardiac angiographic procedures. Most of these protocols involve treatment beginning 24 hours or more prior to the contrast exposure. Extended pretreatment and hydration protocols are not practical for the emergency department patient. In addition, CIN is much less common after IV contrast exposure for computed tomography scans than for intra-arterial coronary procedures. The administration of IV fluids to expand intravascular volume before, during, and after the contrast procedure is the mainstay of CIN prevention.

Periprocedural hydration has been shown to be preventive for CIN in most trials and in several large meta-analyses. One retrospective cohort review, however, showed an increased risk for CIN with isotonic sodium bicarbonate solution.[1] The control group was not well defined and it is unclear whether patients getting the control treatment were getting hydration with some other isotonic solution (ie, sodium chloride) or were getting no hydration at all.

Hogan and coworkers[2]produced a large meta-analysis comparing sodium bicarbonate and sodium chloride as periprocedural hydration for contrast procedures. Their study showed that sodium bicarbonate was vastly superior in preventing CIN. However, heterogeneity of patients within the included random controlled trials, and assessment of publication bias within those randomized controlled trials suggest that the results of the meta-analysis were overly influenced by the large treatment effect seen in several small studies. Thus the benefit of sodium bicarbonate may not be as large as calculated. However, a fail-safe analysis in the Hogan study did show that the treatment effect is real and is not likely to be a type 1 error.The evidence suggests that bicarbonate does, in fact, decrease the incidence of CIN.

Conclusions

Preprocedure hydration seems to be the best strategy for preventing CIN. Isotonic sodium bicarbonate is probably the best fluid for hydration, but a large randomized controlled trial comparing sodium bicarbonate with normal saline is required to clearly establish superiority in CIN prevention.

Comments

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