Catecholamine responses to anesthetic induction with fentanyl and sufentanil

Fentanyl but not Morphine Interacts with Nonopioid Recombinant Human Neurotransmitter Receptors and Transporters

Synthetic opioids, including fentanyl and its analogs, have therapeutic efficacy in analgesia and anesthesia. However, their illicit use in the United States has increased and contributed to the number one cause of death for adults 18-50 years old. Fentanyl and the heroin metabolite morphine induce respiratory depression that can be treated with the μ opioid receptor (MOR) antagonist naloxone. With higher or more rapid dosing, fentanyl, more than morphine, causes chest wall rigidity and can also induce rapid onset laryngospasm. Because non-MORs could mediate differing clinical manifestations, we examined the interactions of fentanyl and morphine at recombinant human neurotransmitter transporters, G protein-coupled receptors, and the N-methyl-D-aspartate glutamate receptor. Both drugs were agonists at MOR, κ, and δ opioid receptors. Morphine had little or no affinity at other human receptors and transporters (K _i or IC₅₀ value >100 µM). However, fentanyl had K _i values of 1407 and 1100 nM at α _1A and α _1B adrenoceptor subtypes, respectively, and K _i values of 1049 and 1670 nM at dopamine D4.4 and D1 receptor subtypes, respectively; it also blocked [³H]neurotransmitter uptake by the vesicular monoamine transporter 2 (IC₅₀ = 911 nM). Pharmacokinetic models indicate that these Ki and IC₅₀ values are pharmacologically relevant. Fentanyl had little affinity for other receptors or transporters. Thus, noradrenergic disposition at specific receptor subtypes in relevant organs may play a role in respiratory and cardiothoracic effects of fentanyl. Data suggest that less selective fentanyl receptor pharmacology could play a role in the different clinical effects of morphine compared with fentanyl, including fentanyl-induced deaths after illicit use. SIGNIFICANCE STATEMENT: The synthetic opioid fentanyl induces different clinical effects, including rapid onset muscular rigidity, vocal cord closure, and rapid death, than the heroin metabolite morphine. Our data indicate for the first time that the two drugs have very different effects at recombinant human neurotransmitter receptors and transporters that might explain those clinical differences.

Renal effects of general anesthesia from old to recent studies

Various types of anesthesia are being utilized to maintain physiologically secured surgical conditions. Nearly all categories of general anesthesia are characterized by various perioperative and postoperative complications. These shortcomings are important aspects that need to be considered by the anesthesiologist and surgeon before administration of these compounds. The renal effects of anesthesia play an important role in understanding possible systemic changes due to the fact that the kidney has a direct or indirect impact on nearly all the systems of the body. Various studies have been conducted to find out changes in renal parameters and its systemic effects upon administration of the anesthesia and its postoperative repercussions. Besides that, the impaired renal function might have an impact on the excretion of anesthetic metabolites, which can lead to long-term dysfunction. Patients with a previous history of disease ought to be brought under consideration because these chemicals can ameliorate pre-existent symptoms. This review is intended to discuss the early and latest studies based on the effects of general anesthesia on the renal system.

Influence of medetomidine on stress-related neurohormonal and metabolic effects caused by butorphanol, fentanyl, and ketamine administration in dogs

OBJECTIVE

To examine stress-related neurohormonal and metabolic effects of butorphanol, fentanyl, and ketamine administration alone and in combination with medetomidine in dogs.

ANIMALS

10 Beagles.

PROCEDURE

5 dogs received either butorphanol (0.1 mg/kg), fentanyl (0.01 mg/kg), or ketamine (10 mg/kg) IM in a crossover design. Another 5 dogs received either medetomidine (0.02 mg/kg) and butorphanol (0.1 mg/kg), medetomidine and fentanyl (0.01 mg/kg), medetomidine and ketamine (10 mg/kg), or medetomidine and saline (0.9% NaCI) solution (0.1 mL/kg) in a similar design. Blood samples were obtained for 6 hours following the treatments. Norepinephrine, epinephrine, cortisol, glucose, insulin, and nonesterified fatty acid concentrations were determined in plasma.

RESULTS

Administration of butorphanol, fentanyl, and ketamine caused neurohormonal and metabolic changes similar to stress, including increased plasma epinephrine, cortisol, and glucose concentrations. The hyperglycemic effect of butorphanol was not significant. Ketamine caused increased norepinephrine concentration. Epinephrine concentration was correlated with glucose concentration in the butorphanol and fentanyl groups but not in the ketamine groups, suggesting an important difference between the mechanisms of the hyperglycemic effects of these drugs. Medetomidine prevented most of these effects except for hyperglycemia. Plasma glucose concentrations were lower in the combined sedation groups than in the medetomidine-saline solution group.

CONCLUSIONS AND CLINICAL RELEVANCE

Opioids or ketamine used alone may cause changes in stress-related biochemical variables in plasma. Medetomidine prevented or blunted these changes. Combined sedation provided better hormonal and metabolic stability than either component alone. We recommend using medetomidine-butorphanol or medetomidine-ketamine combinations for sedation or anesthesia of systemically healthy dogs.

Stress response in infants undergoing cardiac surgery: a randomized study of fentanyl bolus, fentanyl infusion, and fentanyl-midazolam infusion

There have been significant changes in the management of neonates and infants undergoing cardiac surgery in the past decade. We have evaluated in this prospective, randomized, double-blinded study the effect of large-dose fentanyl anesthesia, with or without midazolam, on stress responses and outcome. Forty-five patients < 6 mo of age received bolus fentanyl (Group 1), fentanyl by continuous infusion (Group 2), or fentanyl-midazolam infusion (Group 3). Epinephrine, norepinephrine, cortisol, adrenocortical hormone, glucose, and lactate were measured after the induction (T1), after sternotomy (T2), 15 min after initiating cardiopulmonary bypass (T3), at the end of surgery (T4), and after 24 h in the intensive care unit (T5). Plasma fentanyl concentrations were obtained at all time points except at T5. Within each group epinephrine, norepinephrine, cortisol, glucose and lactate levels were significantly larger at T4 (P values < 0.01), but there were no differences among groups. Within groups, fentanyl levels were significantly larger in Groups 2 and 3 (P < 0.001) at T4, and among groups, the fentanyl level was larger only at T2 in Group 1 compared with Groups 2 and 3 (P < 0.006). There were no deaths or postoperative complications, and no significant differences in duration of mechanical ventilation or intensive care unit or hospital stay. Fentanyl dosing strategies, with or without midazolam, do not prevent a hormonal or metabolic stress response in infants undergoing cardiac surgery.

IMPLICATIONS

We demonstrated a significant endocrine stress response in infants with well compensated congenital cardiac disease undergoing cardiac surgery, but without adverse postoperative outcome. The use of large-dose fentanyl, with or without midazolam, with the intention of providing "stress free" anesthesia, does not appear to be an important determinant of early postoperative outcome.

Dose-response to anaesthetic induction with sufentanil: haemodynamic and electroencephalographic effects

PURPOSE

To determine the effect of a five-fold variation in sufentanil dose on the haemodynamic and electroencephalo graphic (EEG) response to anaesthetic induction and tracheal intubation.

METHODS

Thirty-four patients undergoing elective coronary artery bypass grafting (CABG) participated in this randomized double-blind study. Patients in Group L (n = 17) received 3 micrograms.kg-1 sufentanil and those in Group H (n = 17) 15 micrograms.kg-1. Premedication was 60 micrograms.kg-1 lorazepam po. Anaesthesia and neuromuscular blockade were induced by infusing sufentanil and 0.15 mg.kg-1 vecuronium i.v. over five minutes. Haemodynamic data and the electroencephalographic (EEG) spectral edge were acquired by computer and compared at Control, Induction and Intubation.

RESULTS

Sufentanil dose did not affect the haemodynamic or EEG response at end-induction. No bradyarrhythmias occurred, and the incidence of hypotension was 12% in both groups. However, during induction apparent electromyographic artifacts and a transiently greater increase in heart rate were observed in Group H. The serum sufentanil concentration at Induction was 6.1 +/- 1.8 ng.ml-1 in Group L and 25.4 +/- 8.8 ng.ml-1 in Group H, and did not correlate with haemodynamic changes. No patient recalled any intraoperative event.

CONCLUSION

Increasing sufentanil dose from 3 to 15 micrograms-1 does not influence the ultimate haemodynamic response to induction. Combined with lorazepam premedication, 3 micrograms-1 sufentanil produces near-maximal haemodynamic and EEG effects and is adequate for induction and tracheal intubation of patients undergoing CABG. Sufentanil 15 micrograms.kg-1 is no more efficacious, and causes transient cardiovascular stimulation.