Renal Function and Stress Response during Halothane or Fentanyl Anesthesia

The effects of anesthesia on hormonal stress response and renal function were measured before institution of cardiopulmonary bypass in two groups of patients undergoing elective coronary artery surgery. Group 1 (10 patients) received fentanyl, 100 μg/kg, and N2O/O2; group 2 (12 patients) received halothane and N2O/O2. Patients in group 1 showed no significant changes in plasma levels of vasopressin, renin, or aldosterone during anesthesia or operation. This same group, however, demonstrated significant decreases in plasma levels of cortisol (8.4 ± 1 to 4.2 ± 1 μg%, p < 0.01), epinephrine (260 ± 72 to 97 ± 28 pg/ml, p < 0.05), and norepinephrine (715 ± 177 to 322 ± 46 pg/ml, p < 0.05) during operation. This was accompanied by an increase in urine volume (2.1 ± 0.8 to 7.6 ± 2 ml/min, p < 0.05), a decrease in urine osmolality (610 ± 82 to 166 ± 60 mOsm/kg, p < 0.01), and urine Na+ (54 ± 12 to 16 ± 4 meq/L, p < 0.01) and no change in creatinine clearance. In contrast, in the group 2 patients during operation plasma levels of cortisol (11.7 ± 2 to 31.1 ± 2 μg%, p < 0.01), aldosterone (60 ± 14 to 106 ± 2 pg/ml, p < 0.01), and vasopressin (10.4 ± 1 to 23.3 ± 3 pg/ml, p < 0.01) all increased. This was accompanied by a significant decrease in creatinine clearance (148 ± 52 to 92 ± 12 ml/min/m2, p < 0.05). The data demonstrate that high dose fentanyl anesthesia can significantly attenuate the hormonal stress response to operation and preserve renal function. They also suggest that decreases in renal function observed with anesthesia and operation may be a reflection of the hormonal changes associated with surgical stimulation.