Influence of morphine anaesthesia on the endocrine-metabolic response to open-heart surgery

Intraoperative epidural blockade prevents the increase in protein breakdown after abdominal surgery

BACKGROUND

The aim of this study was to investigate the effect of epidural blockade with bupivacaine, restricted to the intraoperative period, on protein catabolism after major abdominal surgery.

METHODS

Fourteen patients undergoing cystoprostatectomy were randomly assigned to receive either general anaesthesia with isoflurane (control group, n=7) or a combination of general anaesthesia and epidural blockade with bupivacaine from segment T4 to S5 (epidural group, n=7). Rates of urea (Ra urea) and glucose production (Ra glucose) were measured three days before and three days after the operation using stable isotope tracers ([15N2]urea, [6,6-2H2]glucose). Protein breakdown was calculated from the urea production rate. Plasma concentrations of metabolic substrates (urea, glucose, lactate, glycerol, amino acids) and hormones (insulin, glucagon, cortisol, adrenaline, noradrenaline) were also determined.

RESULTS

Protein breakdown significantly increased after surgery in the control group (P<0.05), while it remained unaltered in the epidural group (control; 66 (54-76), epidural; 43 (29-58) mg x kg(-1) x h(-1), P<0.05, median (range)). Glucose plasma concentration and Ra glucose increased in both groups to a similar extent (P<0.05). Plasma concentration of branched chain amino acids decreased after epidural analgesia to a value significantly lower than in the control group (P<0.05). Glutamine plasma concentration decreased in the control group (P<0.05), but did not change in the epidural group. There were no differences in plasma concentrations of insulin, cortisol and catecholamines between the two groups. Glucagon plasma concentration in the epidural group was significantly lower than in the control group (P<0.05).

CONCLUSION

Intraoperative epidural blockade inhibits the increase in protein breakdown after abdominal surgery.

Effects of surgery on endocrine and metabolic responses to anaesthesia in horses and ponies

The effects of surgery on endocrine and metabolic responses to anaesthesia were investigated in seven horses and eight ponies. They were anaesthetised twice and surgery was carried out on one occasion. Cardiorespiratory monitoring was performed and blood samples were taken for assay of cortisol, glucose, lactate, insulin, catecholamines and non-esterified fatty acids. All groups developed arterial hypotension which was more marked in the surgical groups where post operative pulse rate was also higher. Plasma cortisol concentration increased in all groups during anaesthesia but remained higher after surgery. Plasma lactate increased in all animals but was higher during surgery. Glucose, insulin and catecholamines did not change significantly during anaesthesia in the horses but NEFA decreased. Plasma glucose increased during anaesthesia in the ponies and was higher in the non-surgical groups. The study suggests that surgery has little additional effect on the stress response to halothane anaesthesia in Equidae.

Persistent endocrine stress response in patients undergoing cardiac surgery

To investigate the endocrine stress response in patients undergoing major surgery with general anesthesia using a balanced technique with sufentanil, isoflurane and midazolam up to the second postoperative day, blood levels of cortisol, epinephrine, norepinephrine, prolactin and growth hormone were determined in 68 males for elective coronary artery bypass grafting (CABG) surgery. Intraoperatively, during extracorporeal circulation none of the measured parameters were significantly increased compared to preoperative values. The endocrine response of patients with perioperative epinephrine medication (n = 32) was not significant different to patients that did not receive exogenous epinephrine (n = 36). On the evening of the day of surgery, levels of cortisol (3 fold), epinephrine (4.7 fold), norepinephrine (1.7 fold) and growth hormone (16.5 fold) were significantly increased. Compared to preoperative values levels of cortisol (3.3 fold), growth hormone (5.5 fold) and norepinephrine (1.8 fold) remained elevated up to the evening of the second postoperative day. In conclusion, the endocrine stress response in patients undergoing CABG-surgery under general anesthesia with sufentanil, midazolam, isoflurane is intraoperatively prevented by anesthesia. Although hemodilution or hormone degradation might be responsible for the lack of an increase in endocrine parameters during CPB, this study indicates that a balanced technique with isoflurane, sufentanil and midazolam is more effective in blocking the endocrine stress response than previously described anesthetic techniques. In the early postoperative period, a sharp increase in cortisol, epinephrine, norepinephrine and growth hormone occurred suggesting that the predominant endocrine stress response begins in the intensive care unit with end of anesthesia. The postoperative elevated levels of cortisol, growth hormone and norepinephrine indicate a persisting stress-response for more than two days after surgical trauma.

Morphine stimulates adrenocorticotropin and cortisol release in the late-term ovine fetus

Opiates are widely used as obstetrical analgesics during pregnancy and, as such, their interactions with the fetal endocrine system may have important consequences. In this study, the effects of morphine administration to fetal sheep in utero on fetal plasma immunoreactive (ir)-ACTH and ir-cortisol were examined. At the lowest dose administered (0.6 mg/h, i.v.) morphine reduced, although not significantly, plasma ir-cortisol levels. A dose-dependent stimulation of cortisol release was observed with higher doses of morphine. Doses of 2.5 and 5.0 mg/h morphine resulted in a significant increase in ir-cortisol with a change from control levels equal to 9.6 +/- 1.1 ng/mL (p = 0.03) and 17.6 +/- 5.1 ng/mL (p = 0.03), respectively. This increase in plasma ir-cortisol was associated with a significant increase in ir-ACTH (111.8 +/- 23.2 pg/mL versus 42.8 +/- 5.1 pg/mL; p = 0.02) that was naloxone-reversible. These effects of morphine were observed in fetal lambs only > 125 d of gestation, suggesting a maturation of functional opioid receptors in the ovine fetal hypothalamic-pituitary-adrenal axis after this time.

A double-blind study of perioperative steroid requirements in secondary adrenal insufficiency

BACKGROUND

Patients treated long-term with supraphysiologic doses of glucocorticoids experience secondary adrenal insufficiency and are routinely given large doses of steroids in the perioperative period to prevent hypotension. Because the dose of steroids required to prevent hypotension is not known, we conducted a randomized, double-blind study to determine whether patients treated long-term with glucocorticoids actually require increased steroids in the perioperative period.

METHODS

Patients who had been taking at least 7.5 mg prednisone daily for several months and had secondary adrenal insufficiency as defined by adrenocorticotropic hormone testing formed the study population. Patients were randomized to two groups. One group received perioperative injections of saline solution alone; the other received perioperative saline solution and cortisol. All patients received their usual daily prednisone dose throughout the study.

RESULTS

Six patients were in the steroid-treated group and 12 were in the saline-treated group. Most subjects underwent major operations such as joint replacements, abdominal operations, and miscellaneous other procedures. Two patients had hypotension, one in each group. Hypotension resolved with volume replacement in both patients. The average pulse rates and blood pressures were similar in both groups during the perioperative period.

CONCLUSIONS

Patients with secondary adrenal insufficiency do not experience hypotension or tachycardia caused by inadequate glucocorticoid levels when given only their daily dose of steroids for surgical procedures.

Influence of acute and chronic morphine or stadol on the secretion of adrenocorticotrophin and its hypothalamic releasing hormone in the rat

The effects of acute and chronic treatment with morphine and stadol on the functional activity of the hypothalamo-pituitary-adrenocortical (HPA) system in the rat were studied by investigating their effects on the secretion of adrenocorticotrophin (ACTH) by the pituitary gland and corticotrophin-releasing hormone (CRH) by the hypothalamus. The acute injection of morphine or stadol (3.5 mg/100 g body weight i.p.) caused a rise at 5 and 25 min followed by a fall at 90 and 120 min in the concentrations of ACTH in the plasma and adenohypophysis and in hypothalamic CRH content. It appears that, in the rat, the response of HPA system to acute morphine or stadol administration could change depending upon the time of courses. In addition, chronic morphine or stadol (0.5 mg/100 g body weight i.p. daily) administration for a period of 7 days have little effect on plasma and adenohypophysis ACTH concentrations and hypothalamic CRH content. This may indicate that drug tolerance might have developed. Conversely, repeated daily doses of morphine or stadol (2 mg/ 100 g body weight i.p.) for 7 days cause a significant lowering of plasma and pituitary ACTH concentrations and hypothalamic CRH content. These data suggest that the effect of both drugs is dose related. Overall, the present results are consistent with an increased release of pro-opiomelanocortin-derived peptides after acute morphine or stadol treatment for a short-term, and with a decreased release of these peptides in chronic treatment. However, the results indicate that morphine and stadol change HPA activity by acting on specific receptors in the hypothalamus and raise the possibility that opioid peptides and their receptors are physiologically important in the control of the secretion of CRH.

Delayed ACTH response to human corticotropin releasing hormone during cardiopulmonary bypass under diazepam-high dose fentanyl anaesthesia

The inhibitory effect of high dose fentanyl (0.1 mg.kg-1) and diazepam (0.5 mg.kg-1) anaesthesia on the pituitary-adrenal response to coronary artery surgery during cardiopulmonary bypass was assessed by comparison of the adrenocorticotropic hormone and cortisol responses to intravenous boluses of either 0.1 mg (n = 14) or 0.2 mg (n = 14) human corticotropin releasing hormone administered 5 min after starting cardiopulmonary bypass, with the responses obtained in a control group (n = 14). Blood samples were taken before inducing anaesthesia, just before cardiopulmonary bypass and at 5, 20, 35, 50, 65 and 80 min thereafter. The administration of human corticotropin releasing hormone at both doses resulted in significantly greater plasma concentrations of adrenocorticotropic hormone at 50, 65 and 80 min compared to the control group; at the other sampling times there were no differences between the three groups. Plasma cortisol concentrations did not vary between the three groups at any sampling time. During cardiopulmonary bypass the early adrenocorticotropic responses to human corticotropin releasing hormone are blunted but later there is a good response, suggesting that the inhibitory effect of high dose fentanyl and diazepam anaesthesia takes place in the hypothalamus.

Peripheral tissue energy metabolism during recovery from hypothermia after cardiopulmonary bypass: effect of amino-acid infusions

We studied the effects of amino-acid administration on the leg exchange of energy substrates and amino-acids during recovery from hypothermia after open heart surgery. Glucose (G, n = 5), glucose and conventional amino-acids (CA, n = 5) or glucose and branched chain amino-acids (BC, n = 5) were infused during recovery from hypothermia after open heart surgery. The leg exchange of energy substrates and amino-acids were measured after arrival at the intensive care unit, after rewarming, and 2h and 4h after rewarming during increasing amino-acid intake. Despite a normal stress response to surgery, reflected by increased energy expenditure and increased concentrations of insulin and catabolic hormones, amino-acids had no effect on the leg exchange of branched chain amino-acids, glutamine, alanine and energy substrates. This suggests that the transport of amino-acids and energy substrates into the cell are impaired after hypothermic cardiopulmonary bypass and intracellular substrates are utilised for the increased demand for energy during rewarming.

[Post-aggression metabolism and peridural anesthesia: modification of catabolism by anesthesia procedures?]

Postoperative catabolic state of metabolism represents a danger for patients in regard to protein degradation. As postoperative nutrition seems already quite optimal, we examined if anaesthesia, predominantly peridural anaesthesia, would be able to reduce postaggressive metabolism. 20 patients with gastrectomy or subtotal gastric resection were randomized either for a combined anaesthesia with PDA and intubation or for balanced fentanyl analgesia. In both groups the typical characteristics of postaggressive metabolism could be demonstrated without any difference.

The neuroanatomy, neurophysiology, and neurochemistry of pain, stress, and analgesia in newborns and children

Beginning with a brief description of mature anatomic pathways and neurotransmitters in the "pain system," this article details their development in the human fetus, neonate, and child. Special emphasis is given to the basic mechanisms and physiologic effects of opioid analgesia. The clinical implications of these data are described, particularly with regard to the maintenance of cardiovascular stability and hormonal-metabolic homeostasis in newborns and children undergoing surgery or other forms of stress.

Multiple feedback regulatory loops upon rat hypothalamic corticotropin-releasing hormone secretion. Potential clinical implications

To examine whether the hypothalamic corticotropin-releasing hormone (CRH) neuron is regulated by CRH, by products of the proopiomelanocortin (POMC) gene, and/or by glucocorticoids, we used a rat hypothalamic organ culture system in which rat CRH secretion from single explanted hypothalami was evaluated by an RIA (iCRH) specific for rat CRH. The effects of graded concentrations of ovine CRH (oCRH), adrenocorticotropin hormone (ACTH), beta-endorphin (beta-EP), alpha-melanocyte-stimulating hormone (alpha-MSH), corticotropin-like intermediate lobe peptide (CLIP), ovine beta-lipotropin (ovine beta-LPH), and dexamethasone (DEX) upon unstimulated and serotonin- (5HT), acetylcholine- (ACh), and norepinephrine-(NE) stimulated CRH secretion were determined. oCRH and DEX inhibited unstimulated iCRH secretion with ID50 at the 10(-8) M range. ACTH had no detectable suppressive effect at 10(-8) M. oCRH, ACTH, and DEX inhibited 5HT-, ACh-, and NE-stimulated iCRH secretion in a dose-dependent fashion. beta-EP, alpha-MSH, and CLIP also inhibited 5HT-induced iCRH secretion. Of the latter peptides, the strongest inhibitor was beta-EP and the weakest was CLIP. Ovine beta-LPH had only a weak inhibitory effect on 5HT-induced iCRH secretion. Generally, the concentrations required for 50% suppression of neurotransmitter-stimulated iCRH secretion were significantly lower than those required for a similar suppression of unstimulated iCRH secretion. In conclusion, these data suggest the presence of multiple negative feedback loops involved in the regulation of the hypothalamic CRH neuron: an ultrashort CRH-mediated loop, a short, hypothalamic POMC-derived peptide loop, and a long, glucocorticoid-mediated negative feedback loop. The potency of these negative feedback loops may be determined by the state of activation of the CRH neuron.

Opiate anaesthesia

Current use of opioids in anaesthesia is reviewed with particular emphasis on the use of opioids in anaesthetic doses, techniques that recently have become popular in cardiovascular anaesthesia. A major benefit of opioid anaesthesia (particularly fentanyl) is the cardiovascular stability which obtains during induction and throughout operation, even in patients with severely impaired cardiac function. Anaesthetic doses of morphine are associated with a higher incidence of cardiovascular disturbances and other problems. Pethidine is unsuitable for cardiovascular surgery because of severe haemodynamic disturbances when high doses are given. Sufentanil and alfentanil may prove more suitable alternatives. High doses of opioids can reduce or prevent hormonal and metabolic responses to the stress of surgery. Even very large doses of fentanyl or its new analogues do not prevent marked increases in plasma catecholamine concentrations in response to cardiopulmonary bypass. The reduction in hormonal and metabolic stress response does not appear to continue postoperatively.

Effect of opiate-receptor blockade on normoglycemic and hypoglycemic glucoregulation

By use of the opiate antagonist naloxone, we have examined the hormonal and metabolic responses to opiate-receptor blockade under basal conditions and during insulin-induced hypoglycemia in normal dogs. Naloxone treatment had no measurable effect on glucose concentration, turnover, and norepinephrine levels, but stimulated plasma epinephrine, glucagon, and cortisol and inhibited insulin release. Insulin (7 mU X kg-1 X min-1) decreased plasma glucose to 42 +/- 4 mg/dl due to an initial decrease in glucose production and an increase in glucose disappearance. Glucose production then increased, and plasma glucose plateaued. After 50 min of insulin infusion, epinephrine levels increased 26-fold (P less than 0.05), norepinephrine and glucagon 3-fold (P less than 0.02), and cortisol 4-fold (P less than 0.01). Similarly, plasma beta-endorphin and adrenocorticotropin (ACTH) were elevated (6-fold, P less than 0.01, and 16-fold, P less than 0.05, respectively). When naloxone was given during insulin-induced hypoglycemia, there was earlier release of epinephrine, glucagon, beta-endorphin, ACTH, and cortisol as well as a greater release of glucagon (P less than 0.001) and cortisol (P less than 0.0001). This resulted in a greater increase in glucose production (P less than 0.01), thus lessening the insulin-induced hypoglycemic excursion. In conclusion, in the dog, endogenous opiates may play a small role in the regulation of basal insulin and glucagon release and can inhibit the pituitary-adrenal axis under basal conditions and during hypoglycemia. Thus increased glucose production in response to insulin-induced hypoglycemia is consistent with the excessive response of counterregulatory hormones during opiate-receptor blockade.

The cardiopulmonary bypass pump-priming fluid and nitrogen balance after open-heart surgery in adults

Different crystalloid cardiopulmonary bypass pump-priming fluids provide very different substrate loads to patients undergoing open-heart surgery. As a result they may modulate the endocrine milieu, and thus might be expected to alter postoperative nitrogen balance. To test this hypothesis, 24 adult patients undergoing open-heart valve surgery were randomized into four matched groups each to receive a different prime, namely: Hartmann's solution, Plasmalyte 148R, Solution 11 R and a prime consisting of equal volumes of Hartmann's solution and 5% dextrose. Accurate nitrogen balance studies were obtained each 24 hours from one day preoperatively to seven days postoperatively.

The results obtained demonstrated that postoperative nitrogen balance was unaffected by the nature of the crystalloid pump prime. Nitrogen balance in the patients studied was better than that reported from other centres in similar patients.

Hormonal effects of high dose naloxone in humans

Utilizing a double-blind crossover design, the hormonal effects of high dose, 2 mg/kg, were compared to low dose, 0.4 mg (approx. 5 micrograms/kg), naloxone administration in physically healthy humans. A significant naloxone dose effect on plasma cortisol levels was found (p less than 0.001), but no significant effect on plasma or serum levels of prolactin, follicle stimulating hormone, luteinizing hormone, norepinephrine or epinephrine. These results confirm involvement of the endogenous opioid system (EOS) in the tonic regulation of the hypothalamicpituitary-adrenal axis, but fail to find evidence of EOS involvement in the regulation of adrenal medullary function or the gonadotrophic axis in man. The results are however consistent with a continuing action of naloxone as an EOS antagonist even at high doses in man.

Adrenal function following coronary bypass surgery

Little is known about adrenocortical function after coronary bypass surgery in which moderate to deep hypothermia and cardiopulmonary bypass are used particularly with intraoperative steroid administration. Therefore, we performed a pilot study in which immediately preoperative and 18-hour postoperative serum cortisol levels were determined in eight patients who received 1.0 to 1.5 gm of methylprednisolone intravenously during surgery; postoperative serum cortisol (3 +/- 1 microgram%) levels were lower than preoperative levels (15 +/- 3 microgram%, p less than 0.05). To determine the possible cause of these striking findings, the effects of moderate to profound hypothermia and cardiopulmonary bypass upon adrenocortical functioning were investigated without the influence of intraoperative steroid administration. Serum cortisol and aldosterone levels and their response to adrenocorticotropic hormone (ACTH) (Cortrosyn) were determined before coronary bypass surgery and at various postoperative intervals in seven patients. Postoperative cortisol and aldosterone levels increased markedly over their preoperative values, reaching a maximum at 6 to 12 hours (cortisol 16 +/- 8 vs 63 +/- 23 micrograms%, p less than 0.05, aldosterone 15 +/- 5 vs 51 +/- 22 ng%, p less than 0.05). Adrenal response to ACTH was normal preoperatively, during rewarming from hypothermia, and 18 hours, and 7 days postoperatively. In summary, normal adrenal responsiveness occurs after coronary bypass surgery, in spite of hypothermic cardiopulmonary bypass and the effects of anesthesia, and a single dose of methylprednisolone during surgery is associated with markedly lower serum cortisol levels and prevents the usual adrenal stress response to bypass surgery for at least 18 hours postoperatively.

Plasma vasopressin response to extracorporeal circulation in children

Plasma vasopressin levels were measured during open-heart surgery in nine children. The control value of vasopressin was 5.5 +/- 1.5 (s.e.mean) microU/ml. During extracorporeal circulation, a maximum 7.3-fold increase of plasma vasopressin level was demonstrated. This high level of vasopressin was considered to have circulatory effects rather than anti-diuretic effects.

Morphine and postoperative rewarming in critically ill patients

Morphine sulfate (MSO4) has been demonstrated to attenuate the stress response. MSO4 might be useful in minimizing the stress associated with the perioperative period, particularly that due to awakening from anesthesia and rewarming. Two groups of critically ill patients who developed hypothermia (35.8 degrees C) during a surgical procedure were studied. The control group was observed during routine medical management. Group II received 1 or 4 mg/kg MSO4 followed by an infusion of 0.2 or 0.5 mg/kg/hr. During the postoperative rewarming period the control group patients demonstrated a major increase in metabolic demand and myocardial work. In group II patients the infusion of MSO4 resulted in a lower metabolic rate. This was associated with a significantly longer rewarming time and a significant reduction in shivering, heat loss, heart rate, mean arterial pressure, and rate-pressure product. Infusion of MSO4 in critically ill patients during the perioperative period suppressed metabolic demands and myocardial work while preserving cardiovascular function.

Long-term beta-receptor blockade--adrenergic and metabolic response to surgery and neurolept anaesthesia

Twenty-six patients on chronic (greater than 3 months) beta-receptor blocking therapy due to ischaemic heart disease and/or hypertension were randomly distributed to a 4-day gradual withdrawal (n = 13) or a continuation of ordinary therapy until a planned cholecystectomy under neurolept anaesthesia (n = 13). Plasma-adrenaline, -noradrenaline, -potassium, -glycerol, -FFA, -insulin and b-glucose were determined perioperatively. The metabolic response to surgery was as expected with hyperglycaemia and depressed insulin levels, which did not differ significantly between the two groups of patients. Plasma-catecholamines showed the highest mean values during emergence from anaesthesia. Plasma-adrenaline and -potassium were constantly highest in the beta-receptor-blocked patients, who also showed indices of a relatively depressed lipolysis compared to patients in whom beta-receptor blockers had been withdrawn. These discrepancies between withdrawal versus continuation of preoperative beta-receptor blockade seemed to be of small clinical importance and did not oppose the present view that beta-receptor blockers should generally be continued during surgery. However, findings in individual patients suggest that beta-receptor blockade may maintain hypoglycaemia in catabolic patients.

The endocrine-metabolic response to postoperative pain

A short review is given on the role of pain as a release mechanism of the endocrine-metabolic response to surgery. It is concluded that: (1) the stress-response is mainly released through afferent neurogenic stimuli from the surgical area; (2) pain may be an additional release mechanism but quantitatively of minor importance compared to other afferent stimuli; (3) neurogenic blockade and analgesia with local anaesthetics prevents a major part of the stress-response to surgery; (4) systemically administered opiates may lessen the postoerative endocrine-metabolic response, but further studies are needed before any definite conclusion can be drawn; and (5) epidural administration of opiates has no major influence on the postoperative stress-responses.

Influence of epidural morphine on postoperative pain, endocrine-metabolic, and renal responses to surgery. A controlled study

In order to assess the analgesic properties of epidural low-dose morphine and its possible influence on the adrenocortical, hyperglycemic, renal, electrolyte and leukocyte responses to surgery and nitrogen excretion, a double-blind randomized study was undertaken in 14 otherwise healthy patients admitted for hysterectomy under halothane, N2O/o2 anesthesia. Before induction of anesthesia, an epidural catheter was introduced into the lumbar epidural space. After induction of anesthesia, either morphine 4 mg in 10 ml saline or 10 ml saline was injected into the epidural space, according to the allocation. Postoperatively, the degree of pain was evaluated by mean of a visual analogue scale (0-10). When pain score exceeded 5 points during the 24 -h trial, either 4 mg morphine in saline or saline was given epidurally. If the pain score did not decrease more than 2 points after an epidural injection, morphine was given parenterally (5 mg i.v. +5 mg i.m.). The results showed that pain scores, duration of pain relief and doses of morphine differed significantly between groups (P less than 0.05). Plasma concentration of cortisol and glucose, plasma-and urine electrolytes, 24-h creatinine and free-water clearances, diuresis, fluid balance, leukocyte count and nitrogen excretion differed insignificantly between groups. In conclusion, epidural low-dose morphine is a superior alternative to conventional postoperative pain treatment because of greater and longer lasting pain relief, without apparent side-effects. The measured endocrine-metabolic and renal response did not differ between groups, indicating that low-dose epidural morphine does not inhibit afferent neurogenic stimuli from the site of surgical trauma.

Fentanyl and the metabolic response to gastric surgery

The effect of the supplementation of nitrous oxide-oxygen anaesthesia with either 50 micrograms fentanyl/kg body weight or 0.5-1.0% halothane on the metabolic and hormonal response to gastric surgery was investigated in 16 patients. Those patients who received fentanyl showed a significant decrease (p less than 0.05) in the hyperglycemic response to surgery after 30 and 90 minutes and a significant decrease (p less than 0.05) in the plasma cortisol response after 30 minutes. Profound respiratory depression occurred at the end of surgery in all patients who were given fentanyl. This required the intravenous administration of naloxone and careful supervision in the early postoperative period. It is concluded that the transient metabolic and endocrine benefits produced by fentanyl do not compensate for the severe respiratory problems postoperatively and thus 'high-dose fentanyl' cannot be recommended for upper abdominal surgery.

Cortisol, glucose, and hemodynamic responses to surgery after naloxone administration

The adrenocortical, hyperglycemic, and hemodynamic responses to cholecystectomy or vagotomy were studied in 16 patients under halothane and N2O/O2 anesthesia. The patients were randomly divided into two groups: eight patients received naloxone in doses used clinically (2.5 microgram/kg i.v.) just before induction of anesthesia, while eight subjects received placebo. The results showed insignificant differences in plasma concentrations of cortisol and glucose between groups. Nor did blood pressure, heart rates, and inspired halothane concentrations differ significantly between groups. Thus, inhibition of opiate receptors and endorphins by naloxone in an otherwise clinically effective dosage does not influence the adrenocortical, hyperglycemic, or hemodynamic responses to surgical stress. We therefore conclude from our data that opiate receptors and endorphins are not involved in the initial phase of the endocrine-metabolic responses to surgery nor are they part of the neural mechanisms mediating stress-induced analgesia.