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Query: UMLS:C0278134 (anesthesia)
 110,339 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To study possible antinociceptive effects of perineurally administered opioids, the rat infraorbital nerve block (IONB) model was employed for investigations of opioids (morphine, meperidine, buprenorphine, ethylketocyclazocine, and fentanyl) of differing receptor selectivity and physicochemical properties such as lipid solubility. Only meperidine in doses greater than 1 mg/kg produced localized analgesia, the duration of which increased dose-dependently. Naloxone failed to counteract the analgesic effects of meperidine. It is concluded that meperidine exerted its effect by a local anesthetic action and not by the activation of opioid receptors in the peripheral nerve. The local anesthetic potency of meperidine was compared with that of lidocaine in peripheral nerve blocks (IONB in rats and sciatic nerve block in guinea pigs), in central nerve blocks (epidural anesthesia in guinea pigs and spinal anesthesia in mice), and in infiltration anesthesia in guinea pigs. Time to onset of block was generally longer for meperidine. Equal amounts of the drugs produced motor blocks of similar durations except in epidural anesthesia where meperidine was clearly shorter. Sensory blocks were longer with meperidine than with lidocaine when applied in equal amounts to the infraorbital nerve and subarachnoidally. The two agents caused a similar duration of sensory block in infiltration anesthesia. Meperidine was shorter than lidocaine in epidural anesthesia. The characteristics of blocks induced by the two agents may be explained by structural differences and associated differences in physicochemical properties such as lipid solubility and pKa.
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PMID:Antinociceptive effects of localized administration of opioids compared with lidocaine. 257 47

Ten ASA physical status I-II patients were studied after obtaining institutional approval and informed consent. All patients were free from endocrine and metabolic disease undergoing elective low risk operation. They were premedicated with pethidine 1.0 mg/kg intramuscularly and diazepam 0.1 mg/kg orally one hour before anesthesia. Anesthesia was induced with thiopental 4 mg/kg and succinylcholine 1.5 mg/kg for tracheal intubation. Anesthesia was maintained with intermittent intravenous injection of fentanyl (50-100 micrograms/kg) and inhalation of N2O-O2 (50%). Ventilation was controlled during surgery. Atracurium (0.4 mg/kg iv) was given for muscle relaxation when needed. Blood samples were obtained from the radial artery 15 min before induction of anesthesia and 5 min after intubation, 15 min, 30 min, 60 min, 120 min during operation and 30 min after operation. Neuropeptide Y (NPY) was determined by radioimmunoassay, catecholamines were determined by radioenzymatic method using CAT-A-KIT (Amersham). Statistical analysis was performed using Student's t-test for paired and unpaired samples. P values less than 0.05 were considered significant. Naloxone 0.4 mg was given by iv at the end of operation in all of the patients to establish adequate spontaneous respiration. The results showed that the plasma NPY was significantly decreased under high dose fentanyl as well as catecholamines.
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PMID:Study of plasma neuropeptide Y and catecholamine levels during high dose fentanyl anesthesia. 263 17

Flupirtine, a novel analgesic agent, was tested on nociceptive activity in neurones of the dorsomedial part of the ventral nucleus of the thalamus (VDM) and ascending axons of the spinal cord of rats under urethane anaesthesia. Activity was elicited by supramaximal stimulation of the sural nerve. Flupirtine injected i.v. dose dependently reduced nociceptive activity in the thalamus and ascending axons. The ED50 of flupirtine in depressing the thalamic response was 1.9 mg/kg, and the ED50 in depressing the C fibre-evoked response in ascending axons was 18 mg/kg. Naloxone reduced the depression of the nociceptive response evoked in the thalamus when applied before but not when applied after flupirtine. The results indicate that flupirtine produces analgesia by spinal inhibition of nociceptive impulse transmission from afferent nerve fibres to neurones sending their axons to the brain and, in addition, by supraspinal inhibition of nociceptive impulse transmission to the thalamus. Opioid mechanisms could be involved in these effects.
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PMID:Flupirtine depresses nociceptive activity evoked in rat thalamus. 284 54

No agent is yet available to reverse respiratory paralysis produced by CNS depressants, such as general anesthetics. In this study naloxone reversed respiratory paralysis induced by thiopental in rats. 25 mg/kg, i.v. thiopental produced anesthesia without altering respiratory rate, increased GABA, decreased glutamate, and had no effect on aspartate or glycine levels compared to controls in rat cortex and brain stem. Pretreatment of rats with thiosemicarbazide for 30 minutes abolished the anesthetic action as well as the respiratory depressant action of thiopental. 50 mg/kg, i.v. thiopental produced respiratory arrest with further increase in GABA and decrease in glutamate again in cortex and brain stem without affecting any of the amino acids studied in four regions of rat brain. Naloxone (2.5 mg/kg, i.v.) reversed respiratory paralysis, glutamate and GABA levels to control values in brain stem and cortex with no changes in caudate or cerebellum. These data suggest naloxone reverses respiratory paralysis produced by thiopental and involves GABA in its action.
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PMID:GABA involvement in naloxone induced reversal of respiratory paralysis produced by thiopental. 289 36

To determine whether infants are more sensitive than older patients to the ventilatory-depressant effects of fentanyl, patients were anesthetized with fentanyl and nitrous oxide (N2O) and ventilatory depression was assessed following elimination of N2O and in the immediate postoperative period. Three groups of patients were studied: infants (1-12 mo old, n = 14), children (1-5 yr old, n = 14), and adults (23-38 yr old, n = 13). Skin-surface PCO2 was measured to determine the peak PCO2 occurring at the end of anesthesia when end-tidal N2O concentration was less than 6%. Naloxone was administered if PCO2 exceeded 70 mmHg. During recovery from anesthesia, ventilatory pattern was recorded using impedance pneumography to determine the longest breath-to-breath interval and the number of episodes of central apnea (defined as breath-to-breath intervals greater than or equal to 10 s in infants and children and greater than or equal to 20 s in adults). Elevation of PCO2 correlated with increasing plasma fentanyl concentrations but did not differ between groups. Four patients (two infants, one child, and one adult) required naloxone. The only subject who had a low plasma fentanyl concentration but required naloxone was a 6-wk-old infant; this was the only subject younger than 3 mo. For each range of fentanyl concentrations, the incidence of apnea increased with age, as did the number of episodes of apnea per subject. Fentanyl-induced ventilatory depression, as assessed by elevation of resting PCO2 during emergence from anesthesia and disruption of ventilatory pattern during recovery from anesthesia, is not greater in infants older than 3 mo than in children and adults.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Fentanyl-induced ventilatory depression: effects of age. 291 58

The use of an alfentanil infusion as a supplement to a nitrous oxide-halothane anesthetic and the pharmacokinetics of alfentanil were evaluated in infants and children undergoing surgery for correction of congenital heart defects. Eleven patients, six infants and five children, were studied. Anesthesia was induced with nitrous oxide-halothane and pancuronium, 0.15 mg/kg. After intubation, anesthesia was maintained with nitrous oxide-oxygen and halothane to a maximum inspired concentration of 0.6%. After administration of atropine, 20 micrograms/kg, alfentanil, 20 micrograms/kg, was given, followed by a continuous infusion of 1 microgram/kg/min, which was stopped after closure of the sternum. Supplemental boluses of alfentanil, 5 micrograms/kg, were given when, during surgery, blood pressure and/or heart rate increased more than 20% above control values. At the end of surgery, after antagonism of residual neuromuscular blockade, the patients were extubated. Arterial blood samples were collected at regular intervals during surgery and for six hours thereafter for determination of alfentanil plasma concentrations by gas chromatography. Pharmacokinetic data were calculated using the method of residuals and noncompartmental moment analysis. Although atropine was administered, heart rate decreased significantly (2.5% to 15%) in all infants after administration of alfentanil. In the older children, blood pressure decreased 10% to 35%. In the period before bypass, three infants and four children needed supplemental boluses of alfentanil. During and after bypass, anesthesia was adequate. All patients could be extubed within 34 minutes of stopping the alfentanil infusion. Naloxone was not required in any patient, and postoperative respiratory depression did not occur. In the infants and children, total plasma clearance was 8.2 +/- 2.2 mL/kg/min and 6.3 +/- 0.8 mL/kg/min, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Alfentanil in infants and children with congenital heart defects. 297 28

A previous demonstration that the ratio of analgesic to anesthetic endpoints is not constant across inhalation anesthetic agents implies that more than one mechanism of action may be operant in general anesthesia. We hypothesized that the endogenous opiate systems might account for this observed disparity in ratios. The tail flick ED50 (TFED50) in response to a heat stimulus, as an index of analgesia, and MAC as an index of anesthesia, were determined in rats treated with either saline or naloxone, 20 mg/kg, and exposed to halothane, enflurane, or isoflurane. Our findings confirmed those of Deady et al., showing a lack of uniformity of ratios of TFED50/MAC, with values of 0.90 +/- 0.03 for halothane, 0.80 +/- 0.04 for enflurane, and 0.70 +/- 0.04 for isoflurane. Naloxone had no effect on TFED50, MAC, or their ratio. If the endogenous opiate system were involved in the analgesic effect of general anesthetics, naloxone would have affected the ratios. We conclude that opiate systems are not involved in the analgesic action of general anesthetics.
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PMID:Naloxone does not antagonize the analgesic effects of inhalation anesthetics. 300 50

Groups of fentanyl-droperidol-pentobarbital-anesthetized dogs (n = 6 dogs/group) were given IV saline solution (control group), graded doses of naloxone (0.01, 0.1, 1.0, 10.0 mg/kg) or fixed doses of 4-aminopyridine (0.5 mg/kg), yohimbine (0.4 mg/kg), or doxapram (5.0 mg/kg) alone or in combination with a fixed dose of naloxone (1.0 mg/kg). The purpose was to determine which drug or drug combination would produce arousal most quickly without producing obvious undesirable side effects. Control group mean arousal time, mean walk time and mean duration of postarousal sedation were 66.1 minutes, 112.4 minutes and 5.6 hours, respectively. Naloxone (1.0 mg/kg) decreased mean arousal time to 10.8 minutes without significantly decreasing mean walk time or mean duration of postarousal sedation. The combination of naloxone + doxapram decreased mean arousal time and mean walk time to 1.0 minute and 57.1 minutes, respectively, without decreasing mean duration of postarousal sedation. In all groups, emergence from anesthesia was smooth. Relapses or undesirable side effects were not observed. Naloxone + doxapram is superior to naloxone alone for arousal of fentanyl-droperidol-pentobarbital-anesthetized dogs.
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PMID:Prompt arousal from fentanyl-droperidol-pentobarbital anesthesia in dogs: a preliminary study. 301 99

The usefulness of physostigmine in reversing post-narcotic depression after general anaesthesia is well proven; so is that of naloxone, a specific opioid analgetics antagonist, in reversing neuroleptic anaesthesia effects. Morphine-like analgetics are widely used as premedication agents, too; on the other hand, physostigmine reverses opioids as well as other psychotropic and narcotic agents. For that reason, positive post-narcotic physostigmine effects could be due to its anti-opioid potency as well. In a double-blind, randomised study, physostigmine and naloxone were evaluated using a clinically based vigilance protocol, and compared with saline solution. Naloxone did not have remarkable advantages as compared with placebo, while physostigmine led to a significantly higher level of vigilance; moreover, that level was reached sooner. The positive effects of physostigmine in restoring a sufficient level of vigilance after general anaesthesia are, in respect of our findings, unrelated to its antagonism to morphine-like analgetics.
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PMID:[Pharmacologic modification of vigilance in the postnarcotic phase-- naloxone or physostigmine?]. 305 53

In 42 patients undergoing major surgery, anaesthesia was induced by intravenous alfentanil 10 micrograms/kg together with methohexitone 1.5 mg/kg or propofol 2 mg/kg. An infusion of six times these doses per hour was then started; the rate was varied subsequently as indicated by the monitoring of arterial blood pressure, heart rate, EEG and frontalis electromyogram. The mean duration of infusion was 76.7 minutes for propofol and 74.5 minutes for methohexitone and the infusion was stopped about 10 minutes before the end of surgery in each group. The induction dose differed, but the total dose requirement for the two drugs was similar. In every case, anaesthesia was satisfactory. Methohexitone caused a significant rise in mean pulse rate throughout anaesthesia (p less than 0.05, paired t-test). There was no change in mean pulse rate during propofol infusion. The dose of alfentanil used provided excellent control of autonomic reflexes, with negligible respiratory depression. Naloxone was not required. Propofol provided better anaesthesia than methohexitone, with fewer side effects (p less than 0.05, Chi squared test), easier control of the level of narcosis and faster recovery (p less than 0.001, t-test after log transformation).
Anaesthesia 1986 Jun
PMID:Propofol and alfentanil infusion. A comparison with methohexitone and alfentanil for major surgery. 308 51


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