乌鸦传媒

NEW YORK, Sept. 2 -- Patients were at no less risk of contrast-induced nephropathy if they were hydrated with sodium bicarbonate rather than sodium chloride during coronary angiography, investigators here reported.

With both solutions, estimated glomerular filtration decreased by 25% or more in similar numbers of patients, Somjot S. Brar, M.D., of Columbia University, and colleagues reported in the Sept. 3 issue of the Journal of the American Medical Association.

Moreover, rates of death, dialysis, myocardial infarction, and cerebrovascular events did not differ between the groups at 30 days or six months.

"Any true difference between the hydration strategies is likely to be small and not clinically significant," the authors concluded.

Contrast-induced nephropathy is a recognized risk of exposure to iodine-containing contrast media. The estimated risk ranges from 2% in low-risk patients to as much as 50% in high-risk patients, the authors said.

The mechanisms of contrast-induced nephropathy remain unclear, they said, but some evidence has suggested renal vasoconstriction leading to medullary ischemia or direct nephrotoxicity.

Animal models of renal failure and limited clinical data suggest that hydration with sodium bicarbonate may prevent contrast-induced nephropathy. One mechanistic theory proposes that alkalinization of tubular urine with sodium bicarbonate attenuates free radical formation and resulting oxidant injury.

To further explore sodium bicarbonate hydration, Dr. Brar and colleagues conducted a randomized clinical trial involving 353 patients undergoing coronary angiography.

The patients were adults with an estimated glomerular filtration rate of ≤60 mL/min/1.73 m² and at least one high-risk characteristic (diabetes, heart failure, hypertension, or age greater than 75).

Median age was 71, 45% had diabetes, and the treatment groups had no significant differences in baseline characteristics.

The patients received either sodium bicarbonate or sodium chloride administrated at the same rate: 3 mL/kg for one hour before angiography followed by 1.5 mL/kg/hr during the procedure and for four hours afterward.

The primary endpoint was the proportion of patients who had at least a 25% decrease in estimated glomerular filtration rate after completion of the procedure.

In the sodium bicarbonate group, 13.3% met the primary endpoint compared with 14.6% of the sodium chloride group, a nonsignificant difference.

The 30-day event rates with sodium bicarbonate versus sodium chloride were:

· Death, 1.7% in each group

· Dialysis, 0.6% versus 1.1%

· MI, 0.6% versus 0%

· Cerebrovascular events, 0% versus 2.2%

Between 30 days and six months, the event rates were:

· Death, 0.6% versus 2.3%

· Dialysis, 0.6% versus 1.1%

· MI, 0.6% versus 2.3%

· Cerebovascular events, 0.6% versus 1.7%

None of the differences was statistically significant.

The authors acknowledged several limitations of the study. These included the fact that contrast-induced nephropathy could not be determined in 12% of patients, but, they noted, all were asymptomatic as outpatients.

They also acknowledged that clinicians were not blinded to treatment assignment, but said that procedure duration and contrast volume were similar in both groups.

Additionally, the study was performed at a single center, which potentially may limit the generalizability of the findings.

Finally, the researchers said, the sodium content of the two infusions differed slightly but were consistent with those used in registration studies.

The study was supported by Kaiser Permanente of Southern California. The authors reported no conflicts of interest.

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