Prevention of Contrast-Induced Nephropathy With Sodium Bicarbonate: A Randomized Controlled Trial

Source:	Merten et al. JAMA 2004; 291(19): 2328-2334
Editor:	Prasad
Summary Methods Results Discussion Summary: ARF after ischemia or contrast thought to be due to free-radical formation, which is promoted in acidic environment (e.g., renal medulla) NaHCO3 protective (vs. NaCl) in previous animal studies This study: incidence of contrast nephropathy lower with bicarb (1.7% vs. 13.6%) Solution: D5 NaHCO3 154 mEq/L load: 3 ml/kg over 1 hour, given 1 hr before contrast maintenance: 1 ml/kg/hr until 6 hours after procedure use 110kg max wt for calculations If bolus --> significant HTN: stop bolus, diurese before injecting contrast, then resume infusion Back to Top of Page Methods: single center, RCT eligible if... 18+ yo stable Cr >= 1.1 mg/dL cardiac cath, CT, arteriography, or TIPSS excluded if... Cr > 8 mg/dL change in Cr >= 0.5 mg/dL in last 24hrs h/o dialysis, multiple myeloma, pulmonary edema or uncontrolled HTN emergency catheterization IV contrast within 2days of study pregancy exposure to dopamine, mannitol, fenoldopam or N-acetylcysteine (a free-radical scavenger) during study period Protocol Group 1: D5NS (154 mEq/L NaCl) Group 2: D4.23 with NaHCO3 154 mEq/L Bolus 3 cc/kg/hr x 1 hr immediately before contrast Infusion 1 ml/kg/hr during procedure and till 6hrs later If wt > 110kg, used 110kg for dose calculations Collected demographic data, serum Cr preop and POD#1 and #2 Contrast-induced nephropathy defined as 25% increase in Cr Power analysis: assuming 15% incidence in control group and 5% in study group, needed 260 pts for 80% power (with alpha = 0.05) Back to Top of Page Results: study halted after 137 pts randomized (119 completed study), because of significantly better outcomes in study group subsequent 191 patients all enrolled in registry, all received bicarb (slightly more dilute IVF, but same mEq doses) similar... demographics (age, sex, ethnicity, h/o DM, weight) similar volume contrast type of procedure (~80% cardiac cath) differences: Grp 2... more with Cr >=2.5 (8 vs. 2) mean baseline Cr higher (p=0.09) Outcomes. Bicarb group... lower incidence contrast-nephropathy (1.7% vs. 13.6%): absolute risk reduction = 11.9% better % change in GFR (+8.5% vs. -0.1%) NNT to prevent 1 case of renal failure = 8.4 analyzing cardiac cath pts separately, benefit even better: 2% vs. 16.7% the 1 pt who had nephropathy also had an acute MI and 24hrs of "profound hypotension" Registry: contrast-nephropathy in 3/191 pts (1.6%) Back to Top of Page Discussion: recent meta-analysis: incidence of contrast-induced nephropathy 2-26% in pts getting N-acetylcysteine + NS vs. 11-45% in NS alone bicarb even better ... may be role for bicarb + N-acetylcysteine success likely not related to volume expansion, but to alkalinization of environment in renal medulla (see article for details): bicarb reduces formation of OH-, and scavenges peroxynitrates and other NO-related reactive species study limitations: single-institution small sample-size early termination Back to Top of Page