ACC: Saline or Bicarbonate Strategies Equivalent Against Contrast Nephropathy

NEW ORLEANS, March 28 -- Intravenous sodium bicarbonate is no better than sodium chloride at preventing renal failure from contrast dye used in cardiac catheterization, researchers here said.

The rate of contrast-induced nephropathy was 13.5% with infusion of sodium chloride starting before angiography compared with 13.6% with sodium bicarbonate infusion, reported Somjot Brar, M.D., of Kaiser Permanente Southern California in Los Angeles.

Because kidney function frequently does not return to normal after the complication, finding the best prevention method is key, Dr. Brar said at the American College of Cardiology meeting.

Newer non-ionic iso-osmolar contrast agents were expected to be the solution to contrast-induced nephropathy, but recent evidence has shown the risk to be similar to that with higher osmolar agents, he said.

"The best evidence we have is hydration, hydration, hydration," he said.

While a previous small study had suggested advantages of sodium bicarbonate over sodium chloride infusion, normal saline has remained the standard, commented William J. French, M.D., of the Harbor-University of California Los Angeles Medical Center, who was not involved in the study.

To more conclusively determine the better method, Dr. Brar and colleagues conducted a single-center study including 353 adults undergoing non-emergency coronary angiography with the non-ionic low osmolar (500 to 850 mosm/kg H20) contrast agent ioxilan (Oxilan).

The researchers selected a group of patients at moderate-to-high risk for contrast-induced nephropathy. Participants had to have baseline glomerular filtration rate (GFR) at least 60 mL/min/1.73 m², stable kidney function, and at least one risk factor such as diabetes, hypertension, history of chronic heart failure, or age greater than 75.

Those with hemodynamic instability, balloon counterpulsation, recent contrast exposure, prior sodium bicarbonate infusion, severe valvular disease, kidney transplant, or only one kidney were excluded.

The groups were similar in baseline characteristics including age, body mass index, and prior myocardial infarction or chronic heart failure. The percentage with severe kidney dysfunction at baseline and the volume of contrast agent used were also similar between groups.

The participants were randomized to infusion of either sodium chloride (0.9% normal saline) or. sodium bicarbonate (150mEq of sodium bicarbonate in 1L of 5% dextrose) at a rate of 3 mL/kg/hr an hour before the procedure then 1.5 mL/kg/hr during the procedure and for 48 hours afterward.

At 30 days, the findings were (saline versus sodium bicarbonate):

• No difference in the primary endpoint of contrast-induced nephropathy incidence measured by a 25% or more decrease in GFR (13.5% versus 13.6%, P=0.97).
• No difference in the secondary endpoint of contrast-induced nephropathy incidence measured by 25% or more increase in creatinine (15.4% versus 16.3%, P=0.82).
• Similar all-cause mortality rates (1.3% versus 2.0%, P=0.60).
• Infrequent need for dialysis in both groups (0.3% versus 0.0%).

There was no subgroup in which sodium bicarbonate was superior to saline.

Sodium chloride solution is easier to administer than sodium bicarbonate, which has to be "cooked up." Therefore, based on the finding of similar efficacy, "normal saline is the way to go," Dr. Brar concluded.