Effect of i.v. furosemide on pelvic urinary oxygen tension in humans.

Urinary oxygen tension may be an index of renal medullary blood flow. The effect of i.v. furosemide on urinary oxygen tension was studied in four patients with indwelling nephrostomy tubes. An intravascular oxygen sensor (Paratrend 7, Biomedical Sensors Ltd, UK) was inserted into the renal pelvis via the nephrostomy and urine oxygen tension measured. In all cases, furosemide 20 mg i.v. produced a decrease in pelvic urinary oxygen. The possible mechanisms and implications are discussed.