An infusion protocol using sodium chloride plus sodium bicarbonate is more effective than sodium chloride alone for preventing contrast-induced nephropathy (CIN) in patients with an impaired glomerular filtration rate (GFR) undergoing coronary angiography or intervention. The dual therapy also is more effective at maintaining long-term kidney function, Japanese researchers report in a study published online March 21, 2011, ahead of print in the American Journal of Cardiology.

The investigators, led by Masayuki Motohiro, MD, of Kyoto Kujo Hospital (Kyoto, Japan), randomized 155 patients with a GFR < 60 ml/min/1.73m² who were undergoing coronary angiography or intervention to receive sodium chloride plus sodium bicarbonate or sodium chloride alone by infusion.

Sodium chloride 154 mEq/L was administered 1 ml/kg/hour before and after the procedure. Those randomized to the combined protocol also received sodium bicarbonate (154 mEq/L in 5% dextrose as an infusion at 1 ml/kg/hour) starting 3 hours before the procedure and continuing until 6 hours afterward.

Decrease in CIN Incidence Noted

While GFR was similar between the two groups at baseline, it was higher in patients in the combined protocol group compared with those in the sodium chloride group on day 2 and at 1 month. The incidence of CIN, defined as a 25% increase in serum creatinine from baseline or an absolute increase of ≥ 0.5 mg/dl appearing within 2 days of receiving contrast media, was more common in patients who received sodium chloride alone (table 1).

Table 1. CIN Incidence and GFR Levels

Abbreviation: CIN, contrast-induced nephropathy; GFR, glomerular filtration rate.

In addition, post-hoc analysis revealed that percent change in GFR after contrast administration improved significantly in the combined protocol group compared with the chloride group on day 1 (4.2% ± 12.1 vs. -0.8% ± 12.7; P = 0.014), day 2 (0.9% ±16.0 vs. -4.6% ± 15.6; P = 0.031), and at 1 month (9.3% ±19.3 vs. 1.5% ± 21.6; P = 0.020) after the procedure.

Improved Outcomes with Combination

“The major finding of this study is that treatment of patients with sodium bicarbonate plus sodium chloride before and after coronary angiography decreased the incidence of CIN compared to use of sodium chloride alone,” the study authors write. “In addition, [estimated] GFR was improved not only in the short term but also for the long term in patients treated with sodium bicarbonate plus sodium chloride.”

“The limitations of our study include the small sample and that it was 2-center study, which may decrease the power of the study. The study design, however, allowed us to make sodium bicarbonate-specific inferences. In addition, our data were limited to 1 month after coronary procedures; [the] effect of sodium bicarbonate on more long-term outcomes in patients with abnormal renal function remains unknown. The dose of sodium bicarbonate chosen was, it may be argued, higher than necessary to prevent CIN. A substantially lower intravenous dose may have been equally effective and this question merits further study.”

Related Stories:

• Early Bolus of Sodium Bicarb Reduces Contrast Nephropathy in Emergent PCI
• Sodium Bicarbonate More Effective Than Saline in CIN Prevention
• No Improvement with Sodium Bicarbonate over Saline for Preventing CIN