Clinicians have been worrying about contrast induced nephropathy for decades. I’m referring to acute kidney injury caused by the infusion of iodinated agents used as part of imaging studies such CT scans. Over time it became standard practice to infuse fluid such as saline or sodium bicarbonate solution as a preventative agent. Patients thought to be at risk for this syndrome are those with underperfused kidneys irrespective of cause. These groups includes patients with kidney, liver, or heart disease as well as patients with longstanding diabetes mellitus.
Of course, such prevention carried the risk of fluid overload with its attendant complications. But if fluid infusion were done with careful monitoring it seemed that complications could be avoided and acute kidney injury secondary to the diagnostic procedures mentioned above could be prevented. So that’s what everyone started to do. As is typical in medicine this prevention lacked carefully performed clinical trials to underpin its utility.
Several problems emerged as the decades passed. The first was that the syndrome (contrast induced nephropathy) was uncommon and therefore it was difficult to assess measures designed to prevent it. A number of studies began to appear which questioned the efficacy of prophylactic fluid administration to patients deemed to be at high risk for this syndrome. Still clinicians were reluctant to forgo such treatment.
The JAMA has just published a multi center study from the Netherlands – Effect of No Prehydration vs Sodium Bicarbonate Prehydration Prior to Contrast-Enhanced Computed Tomography in the Prevention of Postcontrast Acute Kidney Injury in Adults With Chronic Kidney Disease – The Kompas Randomized Clinical Trial. OK, it’s not “Call me Ishmael” but it does convey what was done. The abstract reads: “Among patients with stage 3 CKD undergoing contrast-enhanced computed tomography, withholding prehydration did not compromise patient safety. The findings of this study support the option of not giving prehydration as a safe and cost-efficient measure.” The studies key finding are shown in the table below. Click on the table for a larger view.
These data appear convincing that doing nothing as opposed to infusing fluid prior to imaging studies following the intravenous infusion of iodinated contrast material resulted in an outcome indistinguishable from that observed in treated patients. Another example where less is, if not more, is the same as more. I leave you to figure out that gnarled sentence on your own.
The study just looked at patients with Stage 3 kidney disease. And it only applies to those receiving intravenous contrast dye. Whether the same result would surface in patient receiving intra-arterial iodinated material is not discerned from this work. Also patients with other risk factors like heart failure or advanced liver disease were not studied and thus we can’t know whether doing nothing in these patients would be as benign as in those with Stage 3 kidney disease. There’s really no way at present to know. So once again physicians will have to make important decisions on the basis of inadequate information. My guess, and it’s nothing more than that, is that prophylactic fluid administration in these individuals will lack beneficial effect.
The Dutch study here mentioned was really hard to do. A similar study in the other conditions just mentioned will be as difficult to satisfactorily complete as the one from the Netherlands, probably more difficult. It’s more than possible that such an investigation will never be done. It’s no fun, much less professionally rewarding, to show that something doesn’t work.
