NEW YORK (Reuters Health) — Patients with chronic kidney disease (CKD) who are administered sodium bicarbonate before emergency coronary procedures might be less likely to suffer contrast-induced nephropathy (CIN), compared to those administered sodium chloride, according to a new study.

The study adds to previous findings that have suggested that sodium bicarbonate can help prevent CIN when administered before elective heart procedures. Some other studies, however, have shown no difference in the effectiveness of sodium chloride and sodium bicarbonate at preventing dangerous increases in serum creatinine levels following fluid administration.

Still, taking previous research into account, “these results suggest that bolus injection of sodium bicarbonate just before contrast injection might be useful for the prevention of CIN, irrespective of the clinical setting,” the authors, led by Dr. Hiromichi Ueda of the Osaka General Medical Center, write in The American Journal of Cardiology.

In the current study, Dr. Ueda and his colleagues randomly assigned 59 patients with CKD who were scheduled to have an emergency coronary procedure to receive either a bolus intravenous injection of 154 mEq/L of sodium bicarbonate or sodium chloride at a dose of 0.5 ml/dg. All patients had glomerular filtration rates of less than 60 ml/min. Emergency coronary procedures included coronary angiography and percutaneous coronary intervention, all scheduled for less than one hour following the injection of sodium bicarbonate or sodium chloride.

Following the treatment procedure, patients in both groups received an infusion of 154 mEq/L sodium bicarbonate for 6 hours, at a dose of 1 ml/kg/hour.

Serum creatinine levels were measured in all patients at baseline, 2 and 3 days after the treatment procedure, and at discharge. CIN was defined as increase in serum creatinine level of more than 25% or more than 0.5 mg/dl within two days after the procedure.

Compared to the baseline reading, serum creatinine levels significantly increased in the sodium chloride group (from 1.51 +/- 0.59 to 1.91 +/- 1.19 mg/dl, P = 0.006) within two days after the procedure, but did not change in the group that received sodium bicarbonate (from 1.32 +/- 0.46 to 1.38 +/- 0.60 mg/dl, P = 0.33). The overall incidence of CIN was significantly lower in patients that received sodium bicarbonate (3.3%) than in those that were pretreated with sodium chloride (27.6%, P = 0.01). Patients in the sodium chloride group, serum creatinine levels remained elevated at discharge.

Heart failure occurred in a total of 11 patients, all following the protocol fluid administration — 5 patients in the sodium bicarbonate group and 6 in the sodium chloride group. There was no difference in the overall incidence of adverse effects in each group.

The study was terminated early because of the authors’ ethnical concerns regarding the continued use of sodium chloride prior to fluid administration.

When speculating on how sodium bicarbonate may prevent CIN, the authors write, “A possible mechanism underlying the prevention of CIN by sodium bicarbonate is that the compound inhibits the development of free radical renal injury through alkalization of the renal tubular fluid.” In other words, infusion of sodium bicarbonate could produce a favorable environment for the passage of contrast medium through the kidney, they write.

Dr. Ueda and his colleagues caution, however, that the study was single-blind and at only one center, with patients who had mild CKD. The results may not be applicable to patients with severe CKD, they write, and a large, double-blind study is necessary to confirm their findings.

The American Journal of Cardiology, online February 25, 2011.