PREPARED: Preparation for Angiography in Renal Dysfunction: a randomized trial of inpatient vs outpatient hydration protocols for cardiac catheterization in mild-to-moderate renal dysfunction.

IV hydration before and after cardiac catheterization is effective in preventing contrast-associated renal dysfunction for patients with mild-to-moderate renal insufficiency, but necessitates overnight hospital admission. We tested an outpatient oral precatheterization hydration strategy in comparison with overnight IV hydration. We randomized 36 patients with renal dysfunction (serum creatinine > or = 1.4 mg/dL) undergoing elective cardiac catheterization to receive either overnight IV hydration (0.45 normal saline solution at 75 mL/h for both 12 h precatheterization and postcatheterization; n = 18) or an outpatient hydration protocol including precatheterization oral hydration (1,000 mL clear liquid over 10 h) followed by 6 h of IV hydration (0.45 normal saline solution at 300 mL/h) beginning just before contrast exposure. The predefined primary end point was the maximal change in creatinine up to 48 h after cardiac catheterization. The inpatient and outpatient groups were well matched for baseline characteristics and contrast volume. By protocol design, the outpatient group received a greater volume of hydration, although the net volume changes were comparable in the two groups. The maximal changes in serum creatinine in the inpatient (0.21+/-0.38 mg/dL; 95% confidence interval [CI], 0.02 to 0.39 mg/dL) and outpatient groups (0.12+/-0.23 mg/dL; 95% CI, 0.01 to 0.24 mg/dL) were comparable (p = not significant). There were no instances of protocol intolerance. A hydration strategy compatible with outpatient cardiac catheterization is comparable to precatheterization and postcatheterization IV hydration in preventing contrast-associated changes in serum creatinine. Hospital admission for IV hydration is unnecessary before elective cardiac catheterization in the setting of mild-to-moderate renal dysfunction.