The effects of high dose morphine and morphine plus nitrous oxide on urinary output in man

Effect of morphine on urine output: possible role of atrial natriuretic factor

We examined the possible role of atrial natriuretic factor (ANF) in morphine-induced diuresis. Morphine (20 micrograms/20 microliters) administered intracerebroventricularly (i.c.v.) in conscious, normally hydrated Sprague-Dawley rats significantly increased urine output from 0.22 +/- 0.16 ml/h/rat to 2.07 +/- 0.46 ml/h/rat, 3 h after injection. Morphine injection also significantly increased the plasma ANF level to a maximum of 364 +/- 46 pg/ml compared to control animals (33 +/- 7 pg/ml) in which 20 microliters of saline was injected i.c.v. (P < 0.001). This peak increase occurred 1 h after morphine administration, however, it continued to remain significantly elevated (171 +/- 36 pg/ml vs. 39 +/- 8 pg/ml in control animals; P < 0.001) 2 h later. The maximal diuresis observed 3 h after administration of morphine i.c.v. was abolished by pretreatment of the animals with 0.8 mg of naloxone given intravenously (i.v.) and also by anti-rat ANF serum (0.4 ml i.v.). A short, transient increase in blood pressure, occurred 2-5 min after morphine administration, but it is unlikely that this increase accounted for the increase in plasma ANF. We conclude that the diuresis induced by i.c.v. administration of morphine is due to enhanced release of ANF.

Fentanyl-oxygen anaesthesia for coronary artery surgery: cardiovascular and antidiuretic hormone responses

This study demonstrates that large doses of fentanyl, as the sole anaesthetic with ventilation with oxygen, produces complete anaesthesia and minimal changes in cardiovasuclar dynamics in patients with coronary artery disease. It also indicates that high dose fentanyl anaesthesia blocks the increase in plasma anti-diuretic hormone and cardiovascular dynamics which are so common with morphine and other anaesthetic techniques during tracheal intubation and surgical stimulation in patients with coronary artery disease. Our findings suggest that fentanyl-oxygen anaesthesia is an attractive technique in patients with coronary artery disease.

Radioimmunoassay of antidiuretic hormone during morphine anaesthesia

The effect of morphine anaesthesia on plasma antidiuretic hormone levels was studied in seven adult patients. Measurements of ADH showed no significant change with morphine and 50 per cent nitrous oxide. Significant elevation occurred with surgical stimulation as previously reported. Changes in urine flow with high doses of morphine are then not ADH related.

The effects of large doses of fentanyl and fentanyl with nitrous oxide on renal function in the dog

Renal effects of large doses of fentanyl (1 mg/kg) were determined in 14 mongrel dogs before and after addition of 50 per cent nitrous oxide. Fentanyl significantly increased urine osmolarity and decreased urine output and free water clearance but did not change inulin or PAH clearances. The arterial blood pressure and cardiac output were significantly decreased after 0.1 mg/kg fentanyl and these changes were then maintained during the remainder of the study period. Addition of nitrous oxide produced no further changes in cardiac output and arterial blood pressure but did increase urine output, PAH, inulin and free water clearances and decreased urine osmolarity. These data demonstrate that high doses of fentanyl have significant antidiuretic properties in the dog and these probably are related to the release of antidiuretic hormone. Our results also indicate that addition of nitrous oxide reverses fentanyl induced antidiuresis.