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Anaesthesia Sep 1979
Topics: Anesthesia, Inhalation; Enflurane; Humans; United Kingdom
PubMed: 525731
DOI: 10.1111/j.1365-2044.1979.tb06407.x -
Anesthesiology Mar 2008Thirty-six halogenated Me Et ethers have been synthesized for evaluation as volatile anesthetics. Eleven of the ethers were too unstable to test, and, of the remaining... (Review)
Review
Thirty-six halogenated Me Et ethers have been synthesized for evaluation as volatile anesthetics. Eleven of the ethers were too unstable to test, and, of the remaining 25, 13 had promising anesthetic properties in mice and are suitable for study in larger animals. Those ethers having one H with at least 2 halogens other than F or 2 or more H with at least one Br or Cl were the best anesthetics.
Topics: Animals; Chemistry, Pharmaceutical; Desflurane; Drug Design; Enflurane; Humans; Hydrocarbons, Fluorinated; Isoflurane; Methyl Ethers; Sevoflurane
PubMed: 18292690
DOI: 10.1097/ALN.0b013e31816499cc -
British Journal of Anaesthesia Jul 1979
Review
Topics: Abnormalities, Drug-Induced; Ambulatory Surgical Procedures; Animals; Chemical and Drug Induced Liver Injury; Electroencephalography; Enflurane; Heart Rate; Hemodynamics; Humans; Kidney Diseases; Kinetics; Muscle Relaxation; Myocardial Contraction; Neoplasms; Respiration
PubMed: 399193
DOI: 10.1093/bja/51.7.627 -
Biophysical Journal May 2003The structural modifications of the dipalmitoylphosphatidylcholine (DPPC) organization induced by increasing concentration of the volatile anesthetic enflurane have been...
The structural modifications of the dipalmitoylphosphatidylcholine (DPPC) organization induced by increasing concentration of the volatile anesthetic enflurane have been studied by differential scanning calorimetry, small-angle, and wide-angle x-ray scattering. The interaction of enflurane with DPPC depends on at least two factors: the enflurane-to-lipid concentration ratio and the initial organization of the lipids. At 25 degrees C (gel state), the penetration of enflurane within the lipids induces the apparition of two different mixed lipid phases. At low anesthetic-to-lipid molar ratio, the smectic distance increases whereas the direction of the chain tilt changes from a tilt toward next-neighbors to a tilt between next-neighbors creating a new gel phase called L(beta')(2NNN). At high ratio, the smectic distance is much smaller than for the pure L(beta') DPPC phase, i.e., 50 A compared to 65 A, the aliphatic chains are perpendicular to the membrane and the fusion temperature of the phase is 33 degrees C. The electron profile of this phase that has been called L(beta)(i), indicates that the lipids are fully interdigitated. At 45 degrees C (fluid state), a new melted phase, called L(alpha)(2), was found, in which the smectic distance decreased compared to the initial pure L(alpha)(1) DPPC phase. The thermotropic behavior of the mixed phases has also been characterized by simultaneous x-ray scattering and differential scanning calorimetry measurements using the Microcalix calorimeter of our own. Finally, titration curves of enflurane effect in the mixed lipidic phase has been obtained by using the fluorescent lipid probe Laurdan. Measurements as a function of temperature or at constant temperature, i.e., 25 degrees C and 45 degrees C give, for the maximal effect, an enflurane-to-lipid ratio (M/M), within the membrane, of 1 and 2 for the L(alpha)(2) and the L(beta)(i) lamellar phase respectively. All the results taken together allowed to draw a pseudo-binary phase diagram of enflurane-dipalmitoylphosphatidylcholine in excess water.
Topics: 1,2-Dipalmitoylphosphatidylcholine; Anesthetics; Anesthetics, General; Enflurane; Lipid Bilayers; Liposomes; Macromolecular Substances; Membrane Fluidity; Membranes, Artificial; Molecular Conformation; Phase Transition; Solutions; Surface Properties; Temperature; Volatilization; Water
PubMed: 12719242
DOI: 10.1016/S0006-3495(03)70037-X -
British Journal of Anaesthesia Dec 1990The temperatures in the aural canal (core), skeletal muscle and skin surface were measured during anaesthesia and surgery in 32 healthy females undergoing total... (Clinical Trial)
Clinical Trial Randomized Controlled Trial
The temperatures in the aural canal (core), skeletal muscle and skin surface were measured during anaesthesia and surgery in 32 healthy females undergoing total abdominal hysterectomy and for 4 h after operation. The patients were allocated randomly to one of four groups according to the end-tidal concentration of volatile anaesthetic: 1 MAC isoflurane, 1 MAC enflurane, 1.8 MAC isoflurane and 1.8 MAC enflurane. The lungs were ventilated with an air-oxygen mixture. Neuromuscular block was produced with pancuronium. Room temperature and i.v. fluid administration were standardized. Aural canal, muscle and mean skin temperatures decreased significantly in all groups during surgery (P less than 0.001). The decrease in core and muscle temperatures, and mean body heat was significantly greater in the 1.8 MAC groups than in the 1 MAC groups for both volatile agents (P less than 0.001). However, there was a significantly greater decrease in core temperature and mean body heat in the isoflurane compared with the enflurane group (P less than 0.026). Body temperature returned to preoperative values during the recovery period. There was a significantly greater rate of rewarming during the first 1 h of recovery in the 1.8 MAC groups compared with the 1 MAC equivalent (P less than 0.001), and this was independent of the volatile agent used. The present results are compared with those reported previously in which nitrous oxide was added to the volatile agents. The decrease in body temperature depends upon the concentration of vapour used. However, it appears that isoflurane, without nitrous oxide, caused greater loss of body heat than enflurane.
Topics: Adult; Air; Anesthesia, Inhalation; Body Temperature; Body Temperature Regulation; Ear Canal; Enflurane; Female; Humans; Hysterectomy; Intraoperative Period; Isoflurane; Middle Aged; Muscles; Oxygen; Postoperative Period; Skin Temperature; Time Factors
PubMed: 2265044
DOI: 10.1093/bja/65.6.754 -
British Journal of Anaesthesia Nov 2006Volatile anaesthetics are widely used agents in clinical anaesthesia, although their mechanism of action is poorly understood. In particular, the dominant molecular...
BACKGROUND
Volatile anaesthetics are widely used agents in clinical anaesthesia, although their mechanism of action is poorly understood. In particular, the dominant molecular mechanisms by which volatile anaesthetics depress spinal neurones and thereby mediate spinal effects such as immobility have recently become a matter of dispute. As GABAA and glycine receptors are potential candidates we investigated the impact of both receptor systems in mediating the depressant effects of isoflurane and enflurane on spinal neurones in rats.
METHODS
The effects of isoflurane and enflurane on spontaneous action potential firing were investigated by extracellular voltage recordings from ventral horn interneurones in cultured spinal cord tissue slices obtained from embryonic rats (E 14-15).
RESULTS
Isoflurane and enflurane reduced spontaneous action potential firing. Concentrations causing half-maximal effects (isoflurane: 0.17 mM; enflurane: 0.50 mM) were less than EC50-immobility (isoflurane: 0.32 mM; enflurane: 0.62 mM). Effects of isoflurane were mediated by 39% by glycine receptors and 36% by GABAA receptors. The effects of enflurane were mediated 26% by GABAA receptors and 29% by glycine receptors.
CONCLUSION
These results demonstrate that the effects of isoflurane and enflurane on GABAA and glycine receptors contribute almost equally to their depressant actions on spinal ventral horn neurones in rats. The fraction of inhibition mediated by both receptor systems differs between specific volatile anaesthetics. Our data argue against the theory that a dominant molecular mechanism accounts for spinal effects of volatile anaesthetics.
Topics: Action Potentials; Anesthetics, Inhalation; Animals; Anterior Horn Cells; Dose-Response Relationship, Drug; Enflurane; Isoflurane; Rats; Rats, Sprague-Dawley; Receptors, GABA-A; Receptors, Glycine; Tissue Culture Techniques
PubMed: 16973644
DOI: 10.1093/bja/ael239 -
British Journal of Anaesthesia Dec 1978Plasma concentrations of thiopentone following the injection of 3.5 mg kg-1 i.v. were studied in six patients who received enflurane and nitrous oxide anaesthesia and...
Plasma concentrations of thiopentone following the injection of 3.5 mg kg-1 i.v. were studied in six patients who received enflurane and nitrous oxide anaesthesia and six volunteers. We identified a three-compartment open model system containing both a "shallow" and a "deep" peripheral compartment in all the patients and half of the controls, and a two-compartment open model for the remaining volunteers. The distribution of thiopentone to the tissues was very rapid, the alpha and beta distribution half-lives averaging 2.5 min and 46.4 min respectively for the patient group and 2.8 min and 48.7 min for the control group. The wide distribution of the drug was indicated by the apparent volume of distribution, the means of which varied between 2 and 1.5 times body weight. The mean elimination half-life was 5.1 h for the patients and 5.7 h for the volunteers. The return of the drug to the central compartment from the deep peripheral compartment was the rate-controlling factor in its elimination. Neither enflurane and nitrous oxide anaesthesia nor the stress of surgery affected the distribution or clearance of the drug from plasma.
Topics: Adult; Anesthesia, General; Enflurane; Female; Half-Life; Humans; Male; Methyl Ethers; Nitrous Oxide; Surgical Procedures, Operative; Thiopental; Time Factors
PubMed: 747695
DOI: 10.1093/bja/50.12.1237 -
Anesthesiology Feb 1991Seven dogs were chronically instrumented for measurements of mean aortic blood pressure and cardiac output and for simultaneous measurements of hepatic, portal, and...
Seven dogs were chronically instrumented for measurements of mean aortic blood pressure and cardiac output and for simultaneous measurements of hepatic, portal, and renal blood flows. Each animal was studied on two separate occasions, awake and during 1.2, 1.4, 1.75, and 2.0 MAC isoflurane and enflurane. Both anesthetics induced tachycardia; to a greater degree than isoflurane, enflurane lowered mean aortic blood pressure in a dose-dependent manner (-37, -45, -48, and -62% vs. -19, -25, -41, and -44%, respectively) and cardiac output (-20, -26, -41, and -48% vs. -3, -5, -11, and -15%, respectively). With isoflurane, cardiac output decreased only at 1.75 and 2.0 MAC, and portal blood flow did not change significantly, whereas hepatic arterial blood flow increased at 1.75 and 2 MAC (by 28 and 33%, respectively). With enflurane, no significant changes were recorded in hepatic arterial blood flow, whereas portal blood flow decreased in a dose-dependent manner. Except at 2 MAC, hepatic circulation did not differ between anesthetics. Likewise, neither anesthetic significantly changed renal blood flow, except for enflurane at 2.0 MAC, which was associated with a 35% reduction. Both anesthetics led to similar systemic, hepatic, and renal vasodilations. Our data suggest that high concentrations of enflurane are associated with decreases in portal, total hepatic, and renal blood flows, most likely as a result of an anesthetic-induced cardiac depression.
Topics: Animals; Dogs; Enflurane; Hemodynamics; Isoflurane; Liver Circulation; Renal Circulation
PubMed: 1990904
DOI: 10.1097/00000542-199102000-00016 -
Anaesthesia Aug 1980
Topics: Chemical and Drug Induced Liver Injury; Enflurane; Humans
PubMed: 7446924
DOI: 10.1111/j.1365-2044.1980.tb03931.x -
Revista Brasileira de Anestesiologia 2011Electroconvulsive therapy (ECT) is commonly used for treatment of depression, mania and affective disorders. Anaesthetics for general anaesthesia during ECT should have... (Comparative Study)
Comparative Study Randomized Controlled Trial
BACKGROUND AND OBJECTIVES
Electroconvulsive therapy (ECT) is commonly used for treatment of depression, mania and affective disorders. Anaesthetics for general anaesthesia during ECT should have rapid onset, rapid emerge, not interfere with seizure activity and not shorten seizure duration. The aim of this study is to compare effects of enflurane, a pro-convulsive anaesthetic agent, and propofol on seizure durations, postictal suppression index and recovery times during electroconvulsive therapy.
METHODS
Unpremedicated subjects were divided into two groups according to induction of anaesthesia. Patients were induced for ECT with 5% enflurane in group E and 1.2mg.kg(-1) propofol in group P until loss of consciousness. The durations of electroencephalogram (EEG) and motor seizures, postictal suppression index, time to spontaneous breathing, duration of eye opening, and obeying commands were recorded.
RESULTS
There was no statistically significant difference between the groups regarding motor and EEG seizure times and postictal suppression index on the EEG records. Recovery times (times of starting spontaneous breathing, eye opening, and obeying command) were significantly shorter in group E compared to group P. No nausea or vomiting were observed and no ECG abnormality was noted except transient sinus bradycardia and sinus tachycardia.
CONCLUSIONS
Although sufficient seizure for the treatment was provided during enflurane anaesthesia, any additional benefit was not revealed regarding seizure times or postictal suppression index when compared to propofol anaesthesia. On the other hand, recovery times after enflurane anaesthesia were shorter than propofol anaesthesia. However, there is still a need for further study in different ETCO(2) levels.
Topics: Adult; Anesthesia Recovery Period; Anesthetics, Inhalation; Anesthetics, Intravenous; Cross-Over Studies; Electroconvulsive Therapy; Enflurane; Female; Humans; Male; Middle Aged; Propofol; Prospective Studies; Seizures; Time Factors; Young Adult
PubMed: 21920208
DOI: 10.1016/S0034-7094(11)70069-1