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At least 127 records · Page 7Linked to original sources
PubMed1993

3 alpha-hydroxy-5 alpha-pregnan-20-one is the only active anesthetic steroid in anesthetized mouse brain.

It was demonstrated that the anesthetic steroid 3 alpha-hydroxy-5 alpha-pregnan-20-one mediates the loss of the righting response (LRR) in mice, in contrast to its metabolites, which are formed in vivo. To reach these conclusions, it was necessary to quantitate levels for 3 alpha-hydroxy-5 alpha-pregnan-20-one and its metabolites at the time of LRR. Methods were used that blocked the production of essentially all of the metabolites. Chromatography of brain extracts by thin-layer chromatography and high-performance liquid chromatography after anesthesia with 3 alpha-hydroxy-5 alpha-[3H]pregnan-20-one showed only a single peak that corresponded to 3 alpha-hydroxy-5 alpha-[3H]pregnan-20-one.

Anesthesia↗
PubMedDate not supplied

EEG-controlled "overdosage" of anesthetics in a patient with a history of intra-anesthetic awareness.

In spite of the ever-growing pharmacologic arsenal available for induction and maintenance of anesthesia, to our knowledge no treatment regimen exists that will provide full protection against intraoperative awareness. To date, no single monitoring technique is able to detect awareness or predict recall. Although the frequency of these complications is rare, the occurrence of any such event can be very distressful for the patient. Based on our clinical experience with a patient with a history of recall and a marked resistance to benzodiazepines, we present electroencephalogram-based anesthetic management as a technique to address this difficult problem.

Adult↗
PubMed2005

Cortical spreading depression (CSD)-induced tolerance to transient focal cerebral ischemia in halothane anesthetized rats is affected by anesthetic level but not ATP-sensitive potassium channels.

We investigated the participation of ATP-sensitive potassium (K(ATP)) channels, adenosine A1 receptors, and the effects of different levels of halothane anesthesia in the development of CSD-induced ischemic tolerance. To elicit CSD, 0.5 M KCl was applied for 2 h to the right hemisphere of halothane anesthetized male Wistar rats. The inhalation concentration of halothane during CSD was maintained at 0.5% (n = 8), 1.0% (n = 8), or 2.0% (n = 8). For control animals, saline was applied instead of KCl (n = 8). To inhibit K(ATP) channels or adenosine A1 receptors, glibenclamide (0.1 mg/kg icv; n = 8), 5-hydroxydeconaoate (5-HD; 100 mg/kg ip; n = 12), or 8-Cyclopentyl-1, 3-dipropylxanthine (DPCPX) (1.0 mg/kg ip; n = 8) was applied before preconditioning during 1.0% halothane anesthesia. Temporary occlusion (120 min) of the right middle cerebral artery was induced 4 days after preconditioning and the infarct volume was measured. Preconditioning elicited under 1.0% halothane reduced cortical infarct volume from 277 +/- 15 mm3 in the control group to 159 +/- 14 mm3 in the CSD group (mean +/- SEM, P < 0.05). In contrast, CSD induced during inhalation of 0.5% or 2.0% halothane did not confer ischemic tolerance. The reduction in infarct area with CSD during inhalation of 1% halothane was not changed in animals treated with glibenclamide or 5-HD or DPCPX. These results uncover a crucial role of halothane level but not of K(ATP) channels or adenosine A1 receptors in the preconditioning effects of CSD.

ATP-Binding Cassette Transporters↗
PubMed2004

An in vivo method for recording single unit activity in lumbar spinal cord in mice anesthetized with a volatile anesthetic.

We describe a method to record single unit neuronal activity from mouse spinal cord using volatile anesthesia. The small size of the mouse can complicate usual methods that are used for single-unit recording in rats, but simple modifications can significantly increase the number of successful recordings. Stabilization of the vertebral column is particularly important, as are adequate ventilation of the animal, control of body temperature and accurate determination of anesthetic concentrations in respiratory gas samples.

Action Potentials↗
PubMed1998

Membrane-buffer partition coefficients of a local anesthetic tetracaine monitored by an anesthetic sensor; effects of temperature and pH.

Binding of a local anesthetic tetracaine (TC) to dimyristoylphosphatidylcholine (DMPC) bilayer membrane was studied by the potentiomerty with an ion-selective electrode sensitive to TC cation. DMPC membrane-buffer partition coefficient (K(app)) was determined in mole fraction unit as a function of pH for the lamellar gel (at 12 degrees C), ripple gel (at 20 degrees C), and liquid crystal (at 30 degrees C) phases. The partition coefficients of charged (K+) and uncharged TC (K0) into the DMPC membranes were estimated from the pH-dependence of K(app). The three states of DMPC membranes were more receptive to the uncharged TC than the charged species.

Algorithms↗
PubMed2004

The effect of inhalant anesthetic and body temperature on peri-anesthetic serum concentrations of transdermally administered fentanyl in dogs.

OBJECTIVES: To determine whether moderate hypothermia during anesthesia significantly affects the serum concentration of transdermally delivered fentanyl and whether halothane or isoflurane affect these concentrations. STUDY DESIGN: Randomized cross-over experimental trial. ANIMALS: Six mature, healthy Beagles (three males, three females) weighing 10.6 +/- 0.43 kg. METHODS: A 50-microg hour(-1) fentanyl patch was applied 36 hours prior to anesthesia. Anesthesia was induced at time 0 (t = 0). Each dog received four treatments: isoflurane + normothermia (ISO-NORM), isoflurane + hypothermia (ISO-HYPO), halothane + normothermia (HAL-NORM), and halothane + hypothermia (HAL-HYPO). Dogs were intubated and maintained at 1.5 times MAC. Animals in the hypothermia treatments were cooled to 35 degrees C during anesthesia. Serum fentanyl analysis was performed at -36, -24, -12, 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 10, 18, and 26 hours. Direct arterial blood pressures and arterial blood gases were monitored. RESULTS: The mean body temperatures (+/-SEM) during the anesthetic period for the four treatments were: ISO-NORM = 37.7 +/- 0.07 degrees C, ISO-HYPO = 35.8 +/- 0.1 degrees C, HAL-NORM = 37.7 +/- 0.06 degrees C, and HAL-HYPO = 35.8 +/- 0.13 degrees C. The mean (+/-SEM) serum fentanyl concentrations (SFC) for both hypothermia treatments were significantly lower than baseline concentrations at t = 1 hour and persisted for the duration of anesthesia for the ISO-HYPO treatment but only from t = 1 to 2 hours for the HAL-HYPO treatment. Serum fentanyl concentrations returned to baseline within one hour of the end of anesthesia, regardless of body temperature. There were no significant differences between treatments for systolic or diastolic blood pressure but mean blood pressures were higher during normothermia versus hypothermia during the last hour of anesthesia. CONCLUSIONS AND CLINICAL RELEVANCE: Hypothermia during inhalation anesthesia produced a significant reduction in SFC using transdermal administration and was more protracted with isoflurane than halothane anesthesia. While significant reductions in SFC occurred, the SFC were still within the range believed to confer analgesia.

Administration, Cutaneous↗
PubMed1997

Electrophysiologic effects of nitrous oxide, a volatile anesthetic, in dogs following myocardial infarction in comparison with other anesthetics.

The present study was undertaken to examine the electrophysiologic effects of nitrous oxide in the dog heart after inducing myocardial infarction, and to compare these with those of other anesthetics. Myocardial infarction was produced by two-stage ligation of the left anterior descending coronary artery in dogs. Seven days after ligation, bipolar electrodes were sutured on the ventricular surface of the infarcted and normal regions for applying electrical stimulation or recording ventricular activation. Ventricular activation time and QT interval on the bipolar electrocardiogram and PQ interval from the standard limb lead II were measured during atrial pacing. Nitrous oxide 80% did not significantly prolong ventricular activation time, PQ interval or QT interval. However, halothane 1 minimum alveolar concentration (MAC), thiopental 5 and 10 mg/kg and fentanyl 30 microg/kg did prolong ventricular activation time; thiopental and fentanyl prolonged the QT interval. Nitrous oxide did not potentiate the effects of fentanyl. Therefore, electrophysiologic effects of nitrous oxide are much weaker compared with those of thiopental, fentanyl or halothane.

Anesthetics, Inhalation↗
PubMedDate not supplied

[Proposal of environmental and biological monitoring and health surveillance of the exposed to inhalation anesthetics. Consensus. A Study Group on Occupational Exposure to Inhalation Anesthetics].

The Study Group on Occupational Exposure to Inhalation Anaesthetics of the Lombardy Association of Occupational Health and Industrial Hygiene prepared a document that was discussed during the Congress "Occupational Risks due to Inhalation Anaesthetics", held in Brescia, Italy, on May 12, 1992. The same document was then approved by the Directory Council of the Lombardy Association of Occupational Health and Industrial Hygiene. Data on environmental concentrations of Nitrous Oxide collected from 1989 to 1991 in 269 operating rooms of 47 hospitals in Lombardy are reported. The measured levels are considerably lower than those collected from the same Study Group from 1985 to 1987 in 111 operating rooms. The methodologies for exposure control are discussed, regarding both environmental and biological monitoring. These two techniques are complementary and can be used with standardized methods. The review of the literature on the early effects showed, even with some uncertainty at the current exposure levels, effects on liver and Central Nervous System. Still controversial are the data regarding the reproductive toxicity. Health surveillance programs have been organized in the last 5 years in 18 Lombardy hospitals and they indicate no cases of pathologies due to inhalation anesthetics on 1498 subjects. Operative proposals are suggested on the methodology and the frequency of environmental/biological monitoring and health surveillance. The "technical limit values" reported in the document from the Italian Ministry of Health are also discussed. Finally, research topics are suggested in order to assess the early effects of exposure.

Anesthesia, Inhalation↗
PubMedDate not supplied

Pleural permeability to local anesthetics--the influence of concentration, pH, and local anesthetic combinations.

The transpleural passage of lidocaine, bupivacaine-lidocaine mixtures, and of bupivacaine, with and without epinephrine, was studied in vitro using pleural from piglets. Our objective was to ascertain whether changing physical parameters of local anesthetics such as pH, concentration, and addition of epinephrine might influence the transfer. Rate of transfer is linearly related to concentration at a given pH, but raising the pH increases the rate for bupivacaine. No change in rate was detectable when the pH of lidocaine was increased or in the rate of transfer of bupivacaine when bupivacaine and lidocaine were mixed. The mixture did however facilitate lidocaine flux. Epinephrine [1:200,000] lowers the pH of the solution dramatically but does not statistically change the transpleural passage of bupivacaine. We conclude that the onset of interpleural blockade may be shortened by using more concentrated solutions of bupivacaine whose pH have been modified by the addition of alkali, by using the higher concentrations of lidocaine or by mixing lidocaine with bupivacaine.

Anesthetics, Local↗
PubMed1988

The neuronal basis of the anesthetic state: a comparative physiological approach. II. The influence of anesthetics on various reactions in flies.

The sensitivity of specific neuronal pathways to Halothane and N2O has been investigated in flies. The effects were tested by monitoring the responses of photoreceptors and their second order neurons, as well as two behavioral responses--a leg reflex induced by light flashes and head movements induced by moving optical patterns--chosen because their neuronal substrates are fairly well known. Sensitivity to both agents rises with the length of dendrites and the number of input synapses of the neurons involved. The findings confirms the hypothesis, formulated in Part I of this paper, that neurons with long dendrites and/or axonal endings and large numbers of input synapses are the elements in the central nervous system with the highest sensitivity to anesthetic action. Under physiological conditions this kind of neuron is capable of "gain-control": the relationship between input and output is modified according to functional requirements. Possible molecular mechanisms leading to functional impairment under anesthesia are discussed.

Anesthesia↗
PubMed1992

Retrospective study of post-anesthetic mild liver disorder associated with inhalation anesthetics, halothane and enflurane.

The incidence of post-anesthetic mild liver disorder (PAMLD) was compared between 928 patients administered halothane and 1766 patients administered enflurane. They were selected from 19 504 surgical patients administered general anesthesia at Kyushu University Hospital over the past 6 years and 4 months. They had had normal liver function before operation and had no history of blood transfusion. Alanine aminotransferase (ALT) levels exceeding 70 IU. l(-1) within 180 days after operation were found in 226 patients in the halothane group (24.4%), and in 250 patients in the enflurane group (14.2%) ( P < 0.01). Both maximum ALT levels and duration of ALT elevation were higher and longer in the halothane group ( P < 0.01). These results suggest that, not only in the development of fulminant hepatitis but also in PAMLD, enflurane is less hepatotoxic than halothane.

Journal Article↗
PubMed1992

Precautions when using alpha-2 agonists as anesthetics or anesthetic adjuvants.

Alpha-2 adrenergic agonists have some unique properties that could theoretically make them useful in the perianesthetic period: they reduce the MAC of inhaled anesthetics, and they are reversible. They also have properties that may limit their usefulness, such as marked decreases in cardiac output. Their clinical utility awaits further studies.

Adjuvants, Anesthesia↗
PubMed1985

Hemodynamic and anesthetic effects of sufentanil as the sole anesthetic for pediatric cardiovascular surgery.

The efficacy, safety, and hemodynamic response to 5 micrograms/kg, 10 micrograms/kg, or 20 micrograms/kg of sufentanil and 0.1 mg/kg pancuronium was evaluated in children between 4 and 12 years of age scheduled for open heart surgery. Systolic time intervals, 2-D echocardiograms, systolic blood pressures (SBP), diastolic blood pressures (DBP), and heart rates (HR) were recorded before and after induction of anesthesia. Significant changes 10 min following induction of anesthesia but before intubation included increases in SBP in the 5 micrograms/kg group (P less than 0.01) and in the ratio of preejection period to left ventricular ejection time in the 20 micrograms/kg group (P less than 0.05). Instances of myoclonic jerking and coughing episodes were observed in all three study groups. Following intubation there were significant (P less than 0.05) increases in SBP in all groups, in DBP in the 5 micrograms/kg group, and in HR in the 5 micrograms/kg and 10 micrograms/kg groups. Smaller increases in SBP, DBP, and HR were seen in all groups after skin incision and sternotomy. Mean plasma catecholamine levels showed nonsignificant increases following periods of intraoperative stimulation with wide patient variations. Recovery of responsiveness to command occurred in all groups within one hour from the end of surgery but extubation was impeded by shallow periodic breathing and hypercapnea. The authors conclude that for children undergoing open heart surgery use of sufentanil as a sole anesthetic in bolus form did not provide a reliable depth of anesthesia with any of the induction doses studied.

Anesthesia, Intravenous↗
PubMed1976

Cardiovascular effects of various anesthetics in man. Four short-acting intravenous anesthetics: althesin, etomidate, methohexital and propanidid.

Four groups of 15 patients without any cardiovascular or pulmonary pathology received an intravenous injection of one of the 4 studied anesthetics, Althesin (0.07 ml/kg), Methohexital (1.6 mg/kg), Etomidate 0.15 mg/kg) or Propanidid (6 mg/kg). Arterial pressure, heart rate, stroke volume and cardiac output were measured every thirty or sixty seconds. Stroke volume decreased and heart rate increased with all of them, but most of all with Propanidid. The only statistically significant reduction of cardiac output was observed with Althesin. Arterial pressures did not vary. Under the conditions of the present study and at the dose levels mentioned, Etomidate produced the least changes in cardiac parameters.

Adult↗
PubMed1977

[Reaction of local myocardial blood flow in non-anesthetized dogs and anesthetized cats to the oral and parenteral administration of a Crateagus fraction (oligomere procyanidines)].

Local blood flow in the myocardium of the left ventricle in unanesthetized dogs was measured by chronically implanted heat-conduction probes. Oral administration of a fraction of Crataegus (oligomere procyanidines) led to a significant rise in blood flow for several hours depending on the dose, the highest increase reaching an average value of about + 70% of the resting flow. In dogs regularly fed with this substance for a longer period of time, a rising tendency of the matutinal resting values of myocardial blood flow towards a maximum was seen. Intravenous application of oligomere procyanidines in anesthetized cats led to a dose-dependent increase in myocardial blood flow for several minutes and a slight decrease in arterial blood pressure.

Administration, Oral↗
PubMed1984

Change of inhalation anesthetic agents for management of ventricular premature depolarizations in anesthetized cats and dogs.

Ventricular premature depolarizations (VPD) were found in 27 cats and 14 dogs during inhalation anesthesia. For animals receiving halothane, the anesthetic agent was changed to enflurane (n = 22) or isoflurane (n = 15). After the change to enflurane, the VPD reverted to normal sinus rhythm (n = 19) or decreased in frequency (n = 3). After the change to isoflurane, the VPD reverted to normal sinus rhythm (n = 14) or decreased in frequency (n = 1). For 4 cats receiving enflurane, the inhalant agent was changed to halothane, which caused an increased frequency of VPD (n = 3) or reversion to normal sinus rhythm (n = 1). It was concluded that cats and dogs with VPD during inhalation anesthesia with halothane would benefit from a change to enflurane or isoflurane.

Anesthesia, Inhalation↗