Patients with pre-existing kidney disease are at high risk of acute renal failure when exposed to radio-contrast dyes, for example during a cardiac angiogram.

The investigators hypothesize that an infusion of saline + furosemide + mannitol will reduce rates of contrast-induced nephropathy when compared with saline infusion controls.

Patients with pre-existing kidney disease are at high risk of acute renal failure when exposed to radio-contrast dyes, for example during a cardiac angiogram.

We hypothesize that an infusion of saline + furosemide + mannitol will reduce rates of contrast-induced nephropathy when compared with saline infusion controls.

We define an episode of contrast nephropathy using the conventional often published definition of a 25% relative increase in serum creatinine OR a 44 umol absolute increase in serum creatinine within 48 hours of contrast exposure.

Inclusion Criteria:

• age > 21 years
• serum creatinine > 150 umol/L
• able and willing to provide informed consent

Exclusion Criteria:

• known hypersensitivity to contrast, furosemide, or mannitol
• unable to tolerate a fluid load (e.g., acute pulmonary edema)
• ESRD, on dialysis
• previous enrollment in this study or previous contrast administration with the last 2 weeks
• refusal by treating physician