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

The effects of narcotic agents and two inhalation anesthetics on intrabiliary pressure (IBP) were measured before and after morphine (0.2 mg/kg), meperidine (2 mg/kg), fentanyl (0.002 mg/kg), or pentazocine (1 mg/kg) given intramuscularly to guinea pigs, and after halothane (0.5, 1.0, 1.5, or 2.0 MAC) or enflurane (same range of MAC) administered by inhalation. All narcotics except pentazocine significantly increase IBP, the increases ranging from 85.7% for meperidine to 143.4% for fentanyl. Pentazocine had no effect on IBP. Peak IBP increases occurred between 9 and 18 minutes after administration. The elevation of IBP produced by narcotics was reversed by atropine (0.05 mg/kg). No statistically significant alterations of IBP were noted during halothane or enflurane anesthesia.
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PMID:Intrabiliary pressure changes produced by narcotic drugs and inhalation anesthetics in guinea pigs. 3 40

Electrocorticographic (ECoG) and depth recordings have previously demonstrated the epileptogenic nature of surgical concentrations of the volatile anesthetic enflurane. We contrasted ECoG activity with local cerebral glucose uptake [( 14C]2-deoxyglucose autoradiography) in 23 brain structures in order to identify the epileptogenic foci. Autoradiograms were obtained from sectioned rat brain following a 30 min period of steady-state anesthesia at 1, 1.5, or 2 MAC (minimum alveolar concentration) enflurane. Pseudo-epileptiform ECoGs were obtained at 1 MAC where bursts of slow waves and sharp waves were evoked by peripheral sensory stimulation. At 1.5 MAC, the ECoG displayed frank, spontaneous epileptiform activity with large amplitude spike-wave complexes; repetitive auditory stimulation occasionally precipitated grand-mal seizures. At 2 MAC, spike complexes were less frequent and could not be repetitively driven. At 1 MAC enflurane, regional cerebral metabolism was generally depressed approximately 14% from the awake controls. However, metabolism in the dentate gyrus of the hippocampus and other subcortical structures in the limbic brain was increased. At 1.5 MAC this dichotomy in local cerebral metabolic rate was maximal; we observed increased metabolism in the hippocampus, habenula, habenulo-interpeduncular tract and interpeduncular nucleus and pineal. Metabolism in all other structures was significantly depressed (P less than 0.05) compared to awake values. At 2 MAC, metabolism was decreased in all structures. We conclude that the low seizure threshold hippocampus and related structures associated with the limbic system and its pathways are the epileptogenic foci for seizures induced with enflurane in the rat. At 1.5 MAC, epileptiform activity spreads throughout the visceral brain when seizure threshold is at a minimum.
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PMID:Local cerebral metabolism during enflurane anesthesia: identification of epileptogenic foci. 9 9

Hypercarbia was induced in 12 patients anesthetized with either halothane or fluroxene in an inspired concentration of approximately 1.3 MAC (1% halothane and 4-5% fluroxene). The six patients receiving halothane anesthesia responded to hypercarbia with a pronounced tachycardia, an increased arterial pressure and an electrocardiographically monitored threshold level for ventricular arrhythmias at a Paco2 level averaging 98 mmHg. The six patients receiving fluroxene anesthesia responded to hypercarbia with both tachycardia and hypertension, but in spite of an average Paco2 level of 109 mmHg, no ventricular arrhythmias could be provoked. It is therefore suggested that within the non-narcotic level of hypercarbia a threshold level for cardiac arrhythmias does not exist under fluroxene anesthesia.
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PMID:Effects of respiratory acidosis on the arrhythmia threshold during fluroxene and halothane anesthesia. 23 95

Maternal and foetal cardiovascular, blood gas and acid-base changes were studied during 90 minutes of methoxyflurane anaesthesia. At 1.0 and 1.5 MAC anaesthesia, despite slight to moderate falls in maternal blood pressure, cardiac output and uterine blood flow, no serious foetal deterioration was seen. 2.0 MAC methoxyflurane was associated with marked falls in maternal blood pressure, cardiac output and uterine blood flow. Foetal hypoxaemia and a mixed respiratory and metabolic acidosis developed. Little foetal cardiovascular depression was seen with any level of anaesthesia. There was no direct effect of methoxyflurane on the uterine vasculature.
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PMID:Maternal and foetal effects of methoxyflurane anaesthesia in the pregnant ewe. 23 12

A brief summary of the anatomy and physiology of the splanchnic circulation is presented. The influence of 1 MAC enflurane anaesthesia on splanchnic circulation and oxygenation was studied in 10 dogs. Superior mesenteric arterial, portal venous and hepatic arterial blood flows decreased less than mean arterial blood pressure, due to reductions in superior mesenteric arterial, preportal vascular and hepatic arterial resistances. It is suggested that these reactions within the splanchnic circulation are mainly dependent on normal autoregulative responses elicited by the fall in blood pressure. Oxygen consumption of the preportal tissues and the liver was unchanged as a result of increased extraction of oxygen.
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PMID:Effects of enflurane on splanchnic circulation. 29

Our experience to date covers 675 kidney grafts performed in the Transplantation Department of the University of Louvain. The evolution of our anaesthesia methods has led us since the end of 1973 to conduct 375 transplantations with enflurane. The patients, aged between 18 months and 50 years, receive a conventional premedication, do not receive corticoids preoperatively nor undergo dialysis immediately prior to operation, but systematically receive a 5-unit transfusion beforehand. Having successively abandoned gallamine, succinylcholine, thiopentone and finally halothane, our present anaesthetic protocol is as follows: induction under benzodiazepines, fentanyl and enflurane, intubation under laryngeal anaesthesia. Maintenance: enflurane (2--3 MAC hours) in open circuit, pancuronium (0.02 mg/kg/h) and occasionally fentanyl. Details and comparative advantages are discussed. This anaesthesia technique combined with the systematic administration of antilymphocytic and antithymocytic serum in the postoperative period, and particularly the preliminary transfusion (producing blocking antibodies), has provided us, using cadaver kidney, with a survival rate of 96% at 6 months, 86% at 1 year and 80% at 2 years, the longest presently being 15 years.
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PMID:Enflurane in renal transplantation: report of 375 cases. 39 56

EEG amplitude dominance in awake man is posterior. During EEG monitoring in patients, the authors observed the abrupt appearance of anterior amplitude dominance during induction of anesthesia with halothane, enflurane, or thiopental. This EEG change is coincident with loss of eyelid reflex and loss of ability to respond to command. This EEG change was studied with several anesthetics in five Java monkeys to determine alveolar anesthetic concentration at which it occurred and to observe the effects of various stimuli on it. EEG recordings were obtained after equilibration at each level with increasing concentrations of halothane, enflurane or isoflurane in oxygen and each agent again in 30 per cent N2O, in separate experiments in the same animals. EEG amplitude dominance became anterior in each animal with each anesthetic and combination at concentrations less than MAC, which was also determined in the same experiments. At lower concentrations, stimulation at equilibrated anesthetic concentrations resulted in abrupt EEG return to posterior amplitude dominance. The end-tidal anesthetic concentration at which persistence of anterior EEG dominance was seen after stimulation was approximately 0.4 MAC for each anesthetic and combination tested. This is interpreted as support for physical solution-lipid solubility theories of anesthetic action. In addition, an EEG change common to various anesthetics may increase the clinical usefulness of EEG monitoring. It is speculated that this EEG change may signal loss of awareness. If so, observance of sustained anterior EEG amplitude dominance may provide assurance of obliteration of awareness during anesthesia.
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PMID:Anterior shift of the dominant EEG rhytham during anesthesia in the Java monkey: correlation with anesthetic potency. 40 70

The antihypertensive agent, clonidine, has a marked sedative effect. We studied whether clonidine also deepens halothane anaesthesia. Eight rabbits were anaesthetized with and without clonidine premedication in a cross-over study. Clonidine premedication (50 microgram/kg subcutaneously) was administered three times daily for 3 days. Tolerance to pain during halothane anaesthesia was tested by compressing the ear with a vessel clamp. Halothane concentrations were determined by gas chromatography. The rabbits premedicated with clonidine tolerated painful stimuli without reactions at lower halothane concentrations in arterial blood and inspired air than unpremedicated rabbits. MAC calculated from blood concentrations was 1.29% for unpremedicated and 1.09% for clonidine-premedicated rabbits. The results suggest that clonidine diminishes the anaesthetic requirement in halothane anaesthesia.
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PMID:The potentiation of halothane anaesthesia by clonidine. 42 9

The effects of enflurane anaesthesia on central circulation, total oxygen uptake, splanchnic circulation and splanchnic oxygen uptake were studied in 10 artifically ventilated dogs, basally anaesthetized with thiopental and nitrous oxide. Hepatic arterial, superior mesenteric arterial and portal venous blood flows were measured with electromagnetic flowmetry. Cardiac output was measured by thermodilution. Determinations of oxygen contents were made in arterial, pulmonary arterial, portal venous and hepatic venous blood. The end-tidal enflurane concentration was kept at about 1 MAC (= 2.2%). Arterial blood pressure diminished 54% of control value due to decreases of cardiac output to 65% and of total peripheral vascular resistance to 81% of control values. Hepatic arterial, superior mesenteric arterial and portal venous blood flows decreased to 65-70% of control levels and the corresponding vascular resistances all declined to about 80-85% of control values. Total oxygen uptake decreased, but less than cardiac output, leading to an increased arterio-venous oxygen content difference. Oxygen uptake of the preportal tissues was unchanged and hepatic oxygen uptake was not significantly altered, although there were decreases in hepatic oxygen uptake in some of the individual experiments. It is suggested that the cardiovascular depression following enflurane anaesthesia in the dog was due, to a great extent, to a primary myocardial depression. It is further concluded that the splanchnic blood flows were relatively well preserved, due to decreases in splanchnic vascular resistances, and that hepatic and preportal tissue oxygen consumptions were maintained by increased oxygen extraction.
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PMID:Effects of enflurane on haemodynamics and oxygen consumption in the dog with special reference to the liver and preportal tissues. 42 10

Aerobic defluorination of the inhalation anaesthetic agent, synthane, was compared with that of methoxyflurane, enflurane and halothane and with two other anaesthetics, isoflurane and sevoflurane. In vitro, in microsomes prepared from phenobarbitone-induced and control livers, synthane and halothane were not defluorinated. The relative order of defluorination of the other anaesthetics was methoxyflurane greater than enflurane greater than isoflurane. In vivo, following 4 h of 1.2% (MAC) synthane anaesthesia, urinary inorganic fluoride excretion was increased by only a trivial amount and only in phenobarbitone-treated rats; polyuria was not observed. Synthane is the least metabolized of the fluorinated ether anaesthetics; its administration will not result in inorganic fluoride nephropathy. An index of nephrotoxic potential for fluorinated anaesthetic agents was formulated utilizing in vitro fluoride production data and oil: gas partition coefficients.
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PMID:Metabolism of synthane: comparison with in vivo and in vitro defluorination of other halogenated hydrocarbon anaesthetics. 50 89


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