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Volatile Anesthetics (volatile + anesthetic)

Distribution by Scientific Domains

Medical Sciences	69%
Chemistry	23%

Selected Abstracts

Effects of isoflurane on nitric oxide metabolism and oxidant status of guinea pig myocardium

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 1 2001
. Durak
Background: Volatile anesthetics (VAs) have been shown to enhance myocardial recovery during reperfusion, the mechanism of which has not been clarified yet. It has been supposed that this effect of VAs may appear through antioxidative mechanisms. Methods: Thirty guinea pigs were used in the study. There were three groups with 10 animals in each: I , control, II , isoflurane+oxygen and III , oxygen. Isoflurane (2.0% v/v) and oxygen (100%) mixture was given to the animals via a face mask in the isoflurane+oxygen group at the rate of 2 l per min for 30 min a day for three consecutive days. In the oxygen group, oxygen alone (100%) was given under the same conditions as in the isoflurane+oxygen group. At the end of the experiments, the animals were killed and their hearts were removed. In the heart tissues, nitric oxide synthase (NOS) activity, nitric oxide (NO) pool (NO,+NO2,) and malondialdehyde (MDA) levels were measured. Results: NOS activity was found to be higher and the NO pool lower in the isoflurane+oxygen group compared with those of control and oxygen groups. In the oxygen group, MDA level was found to be higher compared to the other groups. There was, however, no significant difference between MDA levels of the control and isoflurane+oxygen groups. Conclusion: Our results suggest that isoflurane prevents peroxidation reactions in heart tissue, possibly by scavenging toxic oxygen radicals produced under hyperoxygenation conditions as occurs with general anesthesia. [source]

A rapid and simple method for determination of halothane, iso,urane and sevo,urane in blood using gas chromatography

BIOMEDICAL CHROMATOGRAPHY, Issue 9 2004
Richard J. Atherley
Abstract We have developed a technique to determine the concentration of volatile anesthetics (halothane, iso,urane and sevo,urane) in blood that is a modi,cation of a method used for volatile anesthetics in Krebs solution. Methylene chloride was the internal standard and chloroform was used to extract the volatile anesthetic from blood. The congealed blood proteins were separated from the chloroform solvent (containing anesthetic) using a two-compartment vial that ,ltered out the proteinaceous material during centrifuging. Recovery averaged 102%. Linearity was excellent (r = 0.992,0.999) in the 50,600, 50,300 and 50,300 µg/mL range for halothane, iso,urane and sevo,urane, respectively. Intra-day and inter-day precisions were likewise excellent, with relative standard deviations <5.3 and <7.1%, respectively. Accuracy ranged from 0.8 to 9.5% of the estimated theoretical value. Extracted anesthetic in chloroform solvent was stable over 4,5 days, with <3% variability. The time from obtaining the blood sample to determination of the concentration from the chromatographic peak was 15 min or less. Copyright © 2004 John Wiley & Sons, Ltd. [source]

A succession of anesthetic endpoints in the Drosophila brain

DEVELOPMENTAL NEUROBIOLOGY, Issue 11 2006
Bruno van Swinderen
Abstract General anesthetics abolish behavioral responsiveness in all animals, and in humans this is accompanied by loss of consciousness. Whether similar target mechanisms and behavioral endpoints exist across species remains controversial, although model organisms have been successfully used to study mechanisms of anesthesia. In Drosophila, a number of key mutants have been characterized as hypersensitive or resistant to general anesthetics by behavioral assays. In order to investigate general anesthesia in the Drosophila brain, local field potential (LFP) recordings were made during incremental exposures to isoflurane in wild-type and mutant flies. As in higher animals, general anesthesia in flies was found to involve a succession of distinct endpoints. At low doses, isoflurane uncoupled brain activity from ongoing movement, followed by a sudden attenuation in neural correlates of perception. Average LFP activity in the brain was more gradually attenuated with higher doses, followed by loss of movement behavior. Among mutants, a strong correspondence was found between behavioral and LFP sensitivities, thereby suggesting that LFP phenotypes are proximal to the anesthetic's mechanism of action. Finally, genetic and pharmacological analysis revealed that anesthetic sensitivities in the fly brain are, like other arousal states, influenced by dopaminergic activity. These results suggest that volatile anesthetics such as isoflurane may target the same processes that sustain wakefulness and attention in the brain. LFP correlates of general anesthesia in Drosophila provide a powerful new approach to uncovering the nature of these processes. © 2006 Wiley Periodicals, Inc. J Neurobiol 66: 1195,1211, 2006 [source]

Binding of the volatile general anesthetics halothane and isoflurane to a mammalian ,-barrel protein

FEBS JOURNAL, Issue 2 2005
Jonas S. Johansson
A molecular understanding of volatile anesthetic mechanisms of action will require structural descriptions of anesthetic,protein complexes. Porcine odorant binding protein is a 157 residue member of the lipocalin family that features a large ,-barrel internal cavity (515 ± 30 Å3) lined predominantly by aromatic and aliphatic residues. Halothane binding to the ,-barrel cavity was determined using fluorescence quenching of Trp16, and a competitive binding assay with 1-aminoanthracene. In addition, the binding of halothane and isoflurane were characterized thermodynamically using isothermal titration calorimetry. Hydrogen exchange was used to evaluate the effects of bound halothane and isoflurane on global protein dynamics. Halothane bound to the cavity in the ,-barrel of porcine odorant binding protein with dissociation constants of 0.46 ± 0.10 mm and 0.43 ± 0.12 mm determined using fluorescence quenching and competitive binding with 1-aminoanthracene, respectively. Isothermal titration calorimetry revealed that halothane and isoflurane bound with Kd values of 80 ± 10 µm and 100 ± 10 µm, respectively. Halothane and isoflurane binding resulted in an overall stabilization of the folded conformation of the protein by ,0.9 ± 0.1 kcal·mol,1. In addition to indicating specific binding to the native protein conformation, such stabilization may represent a fundamental mechanism whereby anesthetics reversibly alter protein function. Because porcine odorant binding protein has been successfully analyzed by X-ray diffraction to 2.25 Å resolution [1], this represents an attractive system for atomic-level structural studies in the presence of bound anesthetic. Such studies will provide much needed insight into how volatile anesthetics interact with biological macromolecules. [source]

Larger tidal volume increases sevoflurane uptake in blood: a randomized clinical study

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 9 2010
B. ENEKVIST
Background: The rate of uptake of volatile anesthetics is dependent on alveolar concentration and ventilation, blood solubility and cardiac output. We wanted to determine whether increased tidal volume (VT), with unchanged end-tidal carbon dioxide partial pressure (PETCO2), could affect the arterial concentration of sevoflurane. Methods: Prospective, randomized, clinical study. ASA physical status 2 and II patients scheduled for elective surgery of the lower abdomen were randomly assigned to one of the two groups with 10 patients in each: one group with normal VT (NVT) and one group with increased VT (IVT) achieved by increasing the inspired plateau pressure 0.04 cmH2O/kg above the initial plateau pressure. A corrugated tube added extra apparatus dead space to maintain PETCO2 at 4.5 kPa. The respiratory rate was set at 15 min,1, and sevoflurane was delivered to the fresh gas by a vaporizer set at 3%. Arterial sevoflurane tensions (Pasevo), Fisevo, PETsevo, PETCO2, PaCO2, VT and airway pressure were measured. Results: The two groups of patients were similar with regard to gender, age, weight, height and body mass index. The mean PETsevo did not differ between the groups. Throughout the observation time, arterial sevoflurane tension (mean±SE) was significantly higher in the IVT group compared with the NVT group, e.g. 1.9±0.23 vs. 1.6±0.25 kPa after 60 min of anesthesia (P<0.05). Conclusion: Ventilation with larger tidal volumes with isocapnia maintained with added dead-space volume increases the tension of sevoflurane in arterial blood. [source]

Levosimendan cardioprotection in acutely ,-1 adrenergic receptor blocked open chest pigs

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 1 2010
C. METZSCH
Background: Levosimendan and volatile anesthetics have myocardial pre-conditioning effects. ,-1 adrenergic receptor antagonists may inhibit the protective effect of volatile anesthetics. No information exists as to whether this also applies to the pre-conditioning effect of levosimendan. We therefore investigated whether levosimendan added to metoprolol would demonstrate a cardioprotective effect. Methods: Three groups of anesthetized open chest pigs underwent 30 min of myocardial ischemia and 90 min of reperfusion by temporary occlusion of the largest side branch from the circumflex artery or the left anterior descending artery. One group (CTRL) served as a control, in another group (BETA), a metoprolol-loading dose was intravenously injected 30 min before ischemia, and in a third group (BETA+L), a levosimendan infusion was added to metoprolol. Myocardial tissue concentrations of glucose, glycerol, and lactate/pyruvate ratio as the primary end-points were investigated with microdialysis in ischemic and non-ischemic tissues. Results: At the end of the ischemic period, statistically significant differences were only found between CTRL and BETA+L in the ischemic myocardium, with a lower lactate/pyruvate ratio, lower glycerol, and higher glucose concentrations in BETA+L as compared with CTRL. There were no differences in non-ischemic myocardium. From 10 to 90 min of reperfusion, no more differences were found between groups. Conclusion: The cardioprotective effect of levosimendan on ischemic metabolism with a reduction in the myocardial lactate/pyruvate ratio, less glycerol accumulation, and better preserved glucose concentration does not seem to be prevented by ,-1 adrenergic receptor antagonism with metoprolol. [source]

Caffeine impairs intramuscular energy balance in patients susceptible to malignant hyperthermia

MUSCLE AND NERVE, Issue 3 2003
Zoran Textor MD
Abstract Malignant hyperthermia (MH) is a metabolic myopathy with an abnormal release of calcium by the sarcoplasmic reticulum (SR), triggered by volatile anesthetics and succinylcholine. Similarly, caffeine enhances Ca2+release by the SR in vitro. In a prospective, randomized study, high-energy phosphates were studied by intramuscular 31-phosphorus magnetic resonance spectroscopy (31P-MRS) in 10 MH-susceptible (MHS) and 7 MH-nonsusceptible (MHN) subjects before and after injection of 0.5 ml caffeine (20 mM). Intramuscular energy balance, measured by the ratios of Pi/PCr and Pi/,-ATP, did not differ between MHS and MHN patients before and after intramuscular caffeine injection. However, within each group, Pi/PCr and Pi/,-ATP increased significantly only in the MHS group. Intramuscular caffeine injection seemed to impair the metabolic balance in MHS individuals. This may reflect a local calcium overload leading to consumption of high-energy phosphates and increase of inorganic phosphate. Intramuscular stimulation by caffeine and 31P-MRS may provide a valuable tool to investigate MH-related metabolic disturbances. Muscle Nerve 28: 353,358, 2003 [source]

Reversal of rocuronium with edrophonium during propofol versus sevoflurane anesthesia

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 2 2001
T. J. Zhou
Background: The use of volatile anesthetics for maintenance of anesthesia can enhance the action of non-depolarizing muscle relaxants and interfere with the reversal of neuromuscular blockade. In this study, we studied the antagonism of rocuronium with edrophonium-atropine during propofol- versus sevoflurane-based anesthesia. Methods: Following induction of anesthesia with propofol (2,2.5 mg kg,1, iv) and fentanyl (1,2 ,g kg,1 iv), rocuronium 0.6 mg kg,1 iv was administered to facilitate tracheal intubation. Patients were then randomized to receive either a propofol infusion (100 ,g kg,1 min,1) or sevoflurane (1.0%, end-tidal) in combination with nitrous oxide 66% for maintenance of anesthesia. Neuromuscular blockade was monitored using electromyography at the wrist, and reversed with edrophonium 1.0 mg kg,1 and atropine 0.015 mg kg,1 when the first twitch hight (T1) of the train-of-four (TOF) stimulation recovered to 25% of the baseline value. Anesthetic maintenance with propofol or sevoflurane was continued following reversal until a TOF ratio of 0.7 was attained. Results: The clinical duration of action (i.e., time to 25% T1 recovery) was similar during both propofol- (39.3±14.6 min) and sevoflurane-based (48.1±19.7 min) anesthesia. However, the reversal time from 25% T1 to TOF ratio of 0.7 was significantly longer with sevoflurane [Median 2.8 (range 0.5,18.8) min] compared with propofol [1.5 (0.75,3) min] (P<0.05). Conclusions: We conclude that the clinical duration of action after a single dose of rocuronium, 0.6 mg kg,1 iv, was similar during both propofol- and sevoflurane-based anesthesia. However, the reversal of rocuronium-induced residual blockade was slower and more variable in the presence of sevoflurane. [source]

Halogenated volatile anesthetics inhibit carbon monoxide-stimulated soluble guanylyl cyclase activity in rat brain

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 3 2000
E. Masaki
Background: Because of halogen contents, halogenated volatile anesthetics (HVA) have a similarity to nitric oxide (NO) in terms of great affinity for the ferrous ion. Interactions between HVA and NO at the ferrous ion of soluble guanylyl cyclase (sGC) have been reported in different tissues. Carbon monoxide (CO), a more stable gas than NO, activates sGC by the same mechanism as NO. This study was undertaken to examine the effect of HVA on CO-stimulated sGC activity in rat brain. Methods: Sprague-Dawley rat brain was homogenized and ultracentrifuged. The resulting supernatant was used as sGC fraction. The fraction was incubated with CO and HVA, and the activity of sGC was determined by measuring cyclic guanosine monophosphate (cGMP) production using an enzyme immunoassay in aliquots of the supernatant. Results: CO clearly increased cGMP production in a dose-dependent manner. Sevoflurane and isoflurane produced significant and dose-dependent inhibition of CO-stimulated sGC activity. There was no difference in the inhibitory effect between the two anesthetics. GTP dose-dependently increased CO-stimulated cGMP production. Both anesthetics decreased GTP production, but the inhibition by the anesthetics was not significant at higher GTP concentrations. Conclusions: These results suggest that HVA can compete with CO at the ferrous ion of sGC and inhibit the activity of this enzyme. [source]

Emergence agitation after cataract surgery in children: a comparison of midazolam, propofol and ketamine

PEDIATRIC ANESTHESIA, Issue 9 2010
JIAYAO CHEN MD
Summary Objectives:, The aim of this study was to determine whether the concurrent use of either of a subhypnotic dose of midazolam, propofol or ketamine with fentanyl just before discontinuing the sevoflurane anesthesia would effectively sedate the children as they recovered and significantly decrease the incidence and severity of emergence agitation and would not delay patient awakening and discharge. Background:, Postoperative emergence agitation may occur in children after general anesthesia with volatile anesthetics. Children who undergo cataract surgery after sevoflurane induction and sevoflurane,remifentanil maintenance may experience this type of agitation. Methods/Materials:, In 120 un-premedicated children aged 1,7 years, mask induction with sevoflurane was performed and they were then randomly assigned to one of the three antiagitation postoperative groups (n = 40). We studied the postoperative antiagitation effects of subhypnotic doses of midazolam combined with fentanyl, propofol with fentanyl or ketamine with fentanyl administered just before discontinuing the sevoflurane anesthesia. A score for the level of agitation can be assigned based on the recovery mental state (RMS) scale and the recently published pediatric anesthesia emergence delirium scale (PAED). Postoperative factors assessed included emergence behaviors, the time to eye opening, the time to discharge from the postanesthesia care unit (PACU) to the ward. Results:, There were significantly more agitated children in the ketamine-group when compared to the midazolam-group or to the propofol-group at all time P < 0.05), especially at 10 and 15 min. The PAED scale showed a significant advantage for midazolam,fentanyl [5 (2,15)] and propofol,fentanyl [6 (3,15)] versus ketamine,fentanyl [10 (3,20)] (P < 0.05). The time to discharge from the PACU to the ward was not significantly different among the groups. Conclusions:, Intravenous administration of a subhypnotic dose of midazolam or propofol in addition to a low dose of fentanyl just before discontinuing the sevoflurane anesthesia was both effective on decreasing the incidence and severity of emergence agitation in children undergoing cataract extraction without significant delaying recovery time and discharge. The effect of midazolam was clearer than that seen with propofol. [source]

Isoflurane is associated with a similar incidence of emergence agitation/delirium as sevoflurane in young children , a randomized controlled study

PEDIATRIC ANESTHESIA, Issue 1 2007
ROLAND RICHARD MEYER MD
Summary Background:, Children may be agitated or even delirious especially when recovering from general anesthesia using volatile anesthetics. Many trials have focused on the newer agents sevoflurane and desflurane but for the widely used isoflurane little is known about its potential to generate agitation. We investigated the emergence characteristics of small children after sevoflurane or isoflurane with caudal anesthesia for postoperative pain control. Methods:, After institutional approval and parental consent, anesthesia was randomly performed with sevoflurane (n = 30) or isoflurane (n = 29) in children at the age of 3.8 ± 1.8 years during surgical interventions on the lower part of the body. After induction, all children received caudal anesthesia with bupivacaine (0.25%, 0.8 ml·kg,1). Postoperatively, the incidences of emergence agitation (EA) and emergence delirium (ED) were measured by a blinded observer using a ten point scale (TPS; EA = TPS > 5 ED = TPS > 7) as well as vigilance, nausea/vomiting and shivering. Results:, The two groups were comparable with respect to demographic data, duration of surgery and duration of anesthesia. There were also no differences in the period of time from the end of surgery until extubation, duration of stay in the PACU, postoperative vigilance and vegetative parameters. Incidence of EA was 30% (9/30) for sevoflurane and 34% (10/29) for isoflurane during the first 60 min in the PACU (P = 0.785). Likewise, the incidence of ED was not different between the groups (20% and 24%, respectively). Conclusions:, In our randomized controlled study, we found no difference in the incidence of EA or ED between sevoflurane and isoflurane. Therefore, the decision to use one or the other should not be based upon the incidence of EA or ED. [source]