Renal dysfunction in the surgical patient: maintenance of high output state with furosemide.

A sustained loss of concentrating ability (renal dysfunction) was identified in 29% of a patient population judged to be at risk for this problem on the basis of clinical criteria. Six patients in this group fulfilled previously developed criteria for early renal failure, i.e., free water clearance CH2O between +15 and -15 ml/hr and no change after furosemide. All of these patients were maintained in the high urinary output state with furosemide. Sequential determinations of free water clearance are a sensitive means of monitoring renal function which permits early identification and therapy of patients with renal vasomotor nephropathy.