Glycosylated and non-glycosylated prolactin forms are increased after opioid administration as part of surgical anaesthesia

OBJECTIVE

Previous studies have shown that non-glycosylated prolactin (NG-PRL) increased more markedly than glycosylated hormone (G-PRL) after TRH or metoclopramide stimulation. The aim of the present study was to determine whether such results could be extended to opioid-induced PRL stimulation.

DESIGN

Open and prospective study. Using a newly developed IRMA specific for NG-PRL, we determined G-PRL and NG-PRL immunoreactivities after administration of 0.8-1.2 mg of the opioid drug phenoperidine as part of an anaesthesia.

PATIENTS

Ten male patients anaesthetized for surgical treatment of a prolapsed lumbar intervertebral disc.

MEASUREMENTS

Samples were obtained hourly pre and post-operatively, and every 15 minutes during operation for determination of plasma PRL, NG-PRL and G-PRL. Plasma cortisol, ACTH and GH levels were measured in an attempt to differentiate the respective roles of stress and opiate agonists in the variations of PRL levels during surgery.

RESULTS

A dramatic increase in PRL levels was observed in all patients from an average of 300 +/- 90 to 1200 +/- 330 mU/l (mean + SEM) 30 minutes after drug administration. The proportion of G-PRL immunoreactivity was not significantly different when basal (25.2%) and stimulated (27%) values were compared (P > 0.05), and when mean increments of NG-PRL and G-PRL were compared (345 and 348%, respectively). The opioid drug induced a significant decrease in cortisol levels after injection and during operation (from 585 +/- 63 to 99 +/- 51 nmol/l) with a concomitant decrease in ACTH levels. GH levels were not significantly altered during anaesthesia but were significantly greater (P < 0.05) after than before surgery (5.0 +/- 1.3 vs 0.98 +/- 0.54 mU/l, respectively).

CONCLUSIONS

We conclude from the present and from previous data that opioid induced anaesthesia is accompanied by an increase in both glycosylated and non-glycosylated PRL and that different PRL secretagogues may induce distinct responses in terms of PRL molecular forms.

Early extubation after coronary artery surgery in efficiently rewarmed patients: a postoperative comparison of opioid anesthesia versus inhalational anesthesia and thoracic epidural analgesia

Twenty-eight patients were studied after uncomplicated aortocoronary bypass surgery with hypothermic cardiopulmonary bypass (CPB). In all patients residual hypothermia was effectively treated by the use of extended rewarming during CPB and postoperatively by an external heat source. This treatment almost eliminated postoperative shivering, and it resulted in the lowering of oxygen uptake, carbon dioxide production, and required ventilatory volumes to stable levels where spontaneous breathing could be used safely. The patients were divided into two groups. In group I (n = 12), intraoperative anesthesia was based on an intravenous (IV) opioid (phenoperidine), which caused persistent respiratory depression and made mechanical ventilation necessary for a mean postoperative time period of 10.7 +/- 3.8 hours even with the rewarming. In group II (n = 16), thoracic epidural analgesia and intraoperative general anesthesia with enflurane were used. In this group, postoperative metabolic and ventilatory requirements were stable and low, finger skin temperature was normalized earlier, systemic vascular resistance was lower, and stroke index was higher. Emergence from anesthesia was uneventful and was achieved early postoperatively in Group II. The patients had good pain relief and were mentally alert. Adequate spontaneous breathing was resumed quickly and endotracheal extubation was performed within the first two postoperative hours (1.6 +/- 0.5 hours). No complications or increased morbidity occurred, and no patient needed to be reintubated in Group II.

Influence of bolus doses of phenoperidine on intracranial pressure and systemic arterial pressure in traumatic coma

The effects of bolus doses of phenoperidine 1-2 mg i.v. either alone, or combined with pancuronium 2-4 mg, were investigated in seven patients in traumatic coma. Phenoperidine alone significantly reduced mean arterial pressure (MAP) by a mean (+/- SEM) of 13.2 (+/- 2.8) mm Hg. Overall there was no significant change in intracranial pressure (ICP) despite the decreases in MAP and, consequently, cerebral perfusion pressure (CPP) decreased (14.0 +/- 2.4 mm Hg) on all but one occasion. In some instances these decreases were considerable (maximum 38 mm Hg). Similar results were obtained when phenoperidine was combined with pancuronium. These findings suggest that the bolus administration of phenoperidine and probably other opiates should be avoided in traumatic coma.

[Peridural analgesia and by phenoperidine in normal labor. Therapeutic trial with a control series]

The perinatal effects of phenoperidine and of epidural anaesthesia were studied in a randomised trial in which only normal patients were studied. Foetal heart rate curves, pH, pCO2 and neonatal clinical behaviour demonstrated that both kinds of analgesia had no harmful effects.

[Hemodynamic effects of equipotent doses of phenoperidine and fentanyl in man]

The haemodynamic effects of phenoperidine and fentanyl were studied in ten patients with craniocerebral trauma who presented no surgical indications. They were all mechanically ventilated with a constant tidal volume and rate and their cardiovascular state was stable. The patients were given 5 gamma/kg of fentanyl intravenously; the haemodynamic measurements were performed at two mn interval for 20 mn. Three hours later, the patients were given 30 gamma/kg of phenoperidine intravenously and the haemodynamic measurements were performed similarly. Phenoperidine and fentanyl had the same effects: a significant fall in heart rate, mean arterial pressure and cardiac index without any change in pulmonary wedge pressure. These changes do not dangerously alter the haemodynamic condition of the patients and thus are not a contra-indication to the general use of phenoperidine and fentanyl in anaesthetic practice and in intensive care.

[Study of recovery and the post-anaesthetic period (author's transl)]

The authors compare recovery and the post-anaesthetic period in 45 patients anaesthetised with a combination of either pentothal, nitrous oxide, fluothane and dolosal (group 1, 24 subjects), or of pentothal, nitrous oxide and phenoperidine (group 2, 21 subjects). The quality of recovery was judged at the end of anaesthesia by determining of occurrence of the first response to 3 types of stimulation (calling the name, noise and pain) and the density of these responses during each minute. During the post-anaesthetic period the respective percentages of wakefulness and sleep were calculated. In this way the authors demonstrate a significant (P less than 0.01) shortening in recovery time for group 2, reactivity to own name occurring first in both groups, and a very significant (P less than 0.001) increase in the percentage of physiological sleep in subjects of group 2 during the post-anaesthetic stage.

Dexclamol, a candidate for neuroleptanalgesia

Dexclamol, a potent neuroleptic, was found to potentiate the anesthetic actions of halothane when given at relatively small dose to albino rats. This effect was further enhanced by the addition of phenoperidine, a potent analgesic, at doses that per se did not influence the effects of halothane. Droperidol was used as a standard. In potentiating the effects of halothane, dexclamol behaved both qualitatively and quantitatively in a manner similar to droperidol. Dexclamol, however, was approximately 37 times less potent than droperidol in antagonizing the vasopressor effects of epinephrine.

Comparison of effect of morphine-like analgesics on transmurally stimulated guinea-pig ileum

1. Morphine-like analgesic drugs caused depression of twitches of the isolated guinea-pig ileum in response to transmural electrical stimulation. The drugs tested were the narcotic analgesics codeine, diamorphine, fentanyl, morphine, morphine-N-oxide, normorphine, oxymorphone, pethidine, phenazocine and phenoperidine and the analgesic narcotic antagonists nalorphine and pentazocine.2. With the first application of one of these drugs the extent of depression of twitches was proportional to concentration. Except in the case of pethidine, there was no further depression when additional drug was added to the organ bath. With the second application of a drug after washing out the first dose, the depressant effect was less; that is, tolerance developed. With pethidine, the depression of twitches was proportional to concentration and tolerance could not be observed.3. When tolerance had been produced by cumulative addition of these drugs, a concentration was reached at which further addition resulted in increased activity of the ileum.4. With codeine, morphine and normorphine, the twitches were increased in height and regular.5. With diamorphine, fentanyl, oxymorphone, pentazocine, phenazocine and phenoperidine there were increased but irregular responses to transmural stimulation.6. Having reached the concentration at which these effects were observed, washout of the drug resulted in reduction of activity; the twitches became smaller or the irregular responses ceased.7. Readministration of a drug after activity of the ileum had been depressed by withdrawal of that drug resulted in restoration of activity, the ileum being dependent on the presence of the drug for its activity.8. Codeine and nalorphine did not produce as great an increase in activity on readministration to a dependent ileum as did morphine: they seem to act as partial agonists in producing this effect.9. In similar experiments with the isolated urinary bladder of the rat and guinea-pig, morphine was less active in depressing responses to stimulation than it was on the ileum, and tolerance to the drug and dependence on it did not occur.10. These observations have been discussed in relation to analgesic activity, tolerance and dependence in man.