Urine norepinephrine excretion in patients undergoing mitral or aortic valve replacement with morphine anesthesia

Urine norepinehprine concentration and excretion were measured before, during and after mitral or aortic valve replacement in four groups of patients anesthetized with 1 to 3 mg/kg of morphine plus oxygen or 0.5 to 1.5 percent halothane and oxygen. All patients were similarly premedicated 90 minutes before operation. A bladder catheter was implanted at the time until anesthesia was begun. Urine was also collected during induction of anesthesia, from the first incision until bypass, during bypass, after bypass, and for 2 hours in the recovery room. Urine was analyzed for norepinphrine via the fluorometric method of Vikota. Urine output of patients undergoing the same prodecure were similar during all study periods irrespective of anesthetic. Mean preoperative urine norepinephrine concentrations and excretions of all groups were also similar. Urine norepinephrine concentrations and excretions in patients receiving halothane were unchanged until the postoperative period, when they became significantly increased. Patients given morphine anesthesia had marked increases in urine norepinephrine concentrations and excretions during induction, at all times intraoperatively, and postoperatively. These data suggest that morphine anesthesia increases norepinephrine blood levels in patients with valvular heart disease undergoing surgical correction.