Contrast-induced nephropathy (CIN) has previously been linked to increased morbidity and mortality, and sodium chloride has been shown to reduce these risks. However, a new study, published June 1 in the American Journal of Cardiology, shows that administering sodium chloride in conjunction with sodium bicarbonate is more effective for preventing CIN than sodium chloride alone. Also, they found that the combination can lead to better long-term renal function.
A previous study has shown that sodium bicarbonate could be more effective than sodium chloride for prophylaxis of CIN, however, this finding is not universal and evidence is still sparse, the authors wrote.
To better understand whether sodium bicarbonate can sidestep CIN in patients with chronic kidney dysfunction, Masayuki Motohiro, MD, of the Kyoto Kujo Hospital in Kyoto, Japan, and colleagues conducted a randomized trial that enrolled 155 patients undergoing coronary angiography who had a glomerular filtration rate (GFR) that was <60 ml/min/1.73 m 2.
During the trial, 78 patients were randomized to receive sodium chloride plus sodium bicarbonate and 77 patients received sodium chloride alone. Patients received a sodium bicarbonate infusion from three hours to six hours after coronary angiography and were treated at two Japanese hospitals between November 2004 and May 2007.
The researchers defined CIN as a 25 percent increase in serum creatinine from baseline or an absolute increase of 0.5 mg/dl or greater that appeared two days prior to contrast.
Motohiro and colleagues reported that patients who received both chloride and bicarbonate had a higher GFR compared with those who received chloride alone on day two, 45.8 versus 40.9 ml/min/1.73 m 2. Patients who received bicarbonate also had higher levels of GFR at one month, 49.5 versus 43.7 ml/min/1.73 m 2.
In the study, CIN occurred in 10 patients in the chloride group and two patients in the bicarbonate group. Ten of these patients had diabetes mellitus. These results led the authors to conclude that the addition of sodium bicarbonate to sodium chloride is more effective to prevent CIN than chloride alone. Additionally, the authors found that sodium bicarbonate also had a long-term benefit in renal function.
“The mechanism by which CIN occurs is not well understood,” the authors wrote. However, they speculated that these mechanisms could be explained by renal vasoconstriction and renal tubular toxicity; the latter of which may cause tubular injury and can generate oxygen free radicals.
“In general, administration of sodium chloride is cornerstone treatment to decrease the risk of CIN,” the authors wrote. “Our data suggest that prophylactic and therapeutic use of sodium bicarbonate plus sodium chloride for preventing CIN improved long-term renal function and further decreased mortality after PCI in patients with chronic kidney disease,” the authors concluded.
Motohiro et al noted that a limitation of the study was the study's small sample size and the fact that the study was only conducted at two centers, which decreased the power of the study.
Lastly, the authors noted that some may argue that the dosage of sodium bicarbonate administered was higher than necessary to prevent CIN and said that further studies should be conducted to evaluate whether or not a lower intravenous dose could have been equally effective.