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Lawley JS, Gatterer H, Dias KA, Howden EJ, Sarma S, Cornwell WK, Hearon CM, Samels M, Everding B, Bruick RK, Hendrix M, Piper T, Thevis M, Levine BD. Safety, hemodynamic effects, and detection of acute xenon inhalation: rationale for banning xenon from sport. J Appl Physiol (1985) 2019; 127:1511-1518. [DOI: 10.1152/japplphysiol.00290.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
This study aimed to quantify the sedative effects, detection rates, and cardiovascular responses to xenon. On 3 occasions, participants breathed xenon (FiXe 30% for 20 min; FiXe 50% for 5 min; FiXe 70% for 2 min) in a nonblinded design. Sedation was monitored by a board-certified anesthesiologist. During 70% xenon, participants were also verbally instructed to operate a manual value with time-to-task failure being recorded. Beat-by-beat hemodynamics were measured continuously by ECG, photoplethysmography, and transcranial Doppler. Over 48 h postadministration, xenon was measured in blood and urine by gas chromatography-mass spectrometry. Xenon caused variable levels of sedation and restlessness. Task failure of the self-operating value occurred at 60–90 s in most individuals. Over the first minute, 50% and 70% xenon caused a substantial reduction in total peripheral resistance ( P < 0.05). All dosages caused an increase in cardiac output ( P < 0.05). By the end of xenon inhalation, slight hypertension was observed after all three doses ( P < 0.05), with an increase in middle cerebral artery velocity ( P < 0.05). Xenon was consistently detected, albeit in trace amounts, up to 3 h after all three doses of xenon inhalation in blood and urine with variable results thereafter. Xenon inhalation caused sedation incompatible with self-operation of a breathing apparatus, thus causing a potential life-threatening condition in the absence of an anesthesiologist. Yet, xenon can only be reliably detected in blood and urine up to 3 h postacute dosing. NEW & NOTEWORTHY Breathing xenon in dosages conceivable for doping purposes (FiXe 30% for 20 min; FiXe 50% for 5 min; FiXe 70% for 2 min) causes an initial rapid fall in total peripheral resistance with tachycardia and thereafter a mild hypertension with elevated middle cerebral artery velocity. These dose duration intervals cause sedation that is incompatible with operating a breathing apparatus and can only be detected in blood and urine samples with a high probability for up to ~3 h.
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Affiliation(s)
- Justin S. Lawley
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Dallas, Dallas, Texas
- University of Texas Southwestern Medical Center, Dallas, Texas
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
| | - Hannes Gatterer
- Institute of Mountain Emergency Medicine, EURAC Research, Bolzano, Italy
| | - Katrin A. Dias
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Dallas, Dallas, Texas
- University of Texas Southwestern Medical Center, Dallas, Texas
| | - Erin J. Howden
- The Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Satyam Sarma
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Dallas, Dallas, Texas
- University of Texas Southwestern Medical Center, Dallas, Texas
| | | | - Christopher M. Hearon
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Dallas, Dallas, Texas
- University of Texas Southwestern Medical Center, Dallas, Texas
| | - Mitchel Samels
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Dallas, Dallas, Texas
| | - Braden Everding
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Dallas, Dallas, Texas
| | | | - Max Hendrix
- University of Texas Southwestern Medical Center, Dallas, Texas
| | - Thomas Piper
- German Sport University Cologne, Institute of Biochemistry/Center for Preventive Doping Research, Cologne, Germany
| | - Mario Thevis
- German Sport University Cologne, Institute of Biochemistry/Center for Preventive Doping Research, Cologne, Germany
| | - Benjamin D. Levine
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Dallas, Dallas, Texas
- University of Texas Southwestern Medical Center, Dallas, Texas
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Schaefer MS, Piper T, Geyer H, Schneemann J, Neukirchen M, Thevis M, Kienbaum P. Xenon elimination kinetics following brief exposure. Drug Test Anal 2016; 9:666-670. [PMID: 27341380 DOI: 10.1002/dta.2001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Revised: 04/22/2016] [Accepted: 05/05/2016] [Indexed: 11/09/2022]
Abstract
Xenon is a modern inhalative anaesthetic with a very low solubility in tissues providing rapid elimination and weaning from anaesthesia. Besides its anaesthetic properties, Xenon promotes the endogenous erythropoietin biosynthesis and thus has been enlisted as prohibited substance by the World Anti-Doping Agency (WADA). For effective doping controls, knowledge about the elimination kinetics of Xenon and the duration of traceability are of particular importance. Seventy-seven full blood samples were obtained from 7 normal weight patients undergoing routine Xenon-based general anaesthesia with a targeted inspiratory concentration of 60% Xenon in oxygen. Samples were taken before and during Xenon inhalation as well as one, two, 4, 8, 16, 24, 32, 40, and 48 h after exposure. Xenon concentrations were assessed in full blood by gas chromatography and triple quadrupole tandem mass spectrometry with a detection limit of 0.25 µmol/L. The elimination of Xenon was characterized by linear regression of log-transformed Xenon blood concentrations, as well as non-linear regression. Xenon exposure yielded maximum concentrations in arterial blood of 1.3 [1.1; 1.6] mmol/L. Xenon was traceable for 24 to 48 h. The elimination profile was characterized by a biphasic pattern with a rapid alpha phase, followed by a slower beta phase showing a first order kinetics (c[Xe] = 69.1e-0.26x , R2 = 0.83, t1/2 = 2.7 h). Time in hours after exposure could be estimated by 50*ln(1.39/c[Xe]0.077 ). Xenon's elimination kinetics is biphasic with a delayed beta phase following a first order kinetics. Xenon can reliably be detected for at least 24 h after brief exposure. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
| | - Thomas Piper
- Center for Preventive Doping Research - Institute of Biochemistry, German Sports University Cologne, Germany
| | - Hans Geyer
- Center for Preventive Doping Research - Institute of Biochemistry, German Sports University Cologne, Germany
| | - Julia Schneemann
- Department of Anaesthesiology, University Hospital Düsseldorf, Germany
| | - Martin Neukirchen
- Department of Anaesthesiology, University Hospital Düsseldorf, Germany
| | - Mario Thevis
- Center for Preventive Doping Research - Institute of Biochemistry, German Sports University Cologne, Germany
| | - Peter Kienbaum
- Department of Anaesthesiology, University Hospital Düsseldorf, Germany
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Abstract
BACKGROUND Anesthetic blood solubility predicts pharmacokinetics for inhaled agents and is essential for determination of blood anesthetic concentrations from end-tidal gas concentrations using Henry's Law. Though used to model anesthetic effects in humans, there are limited interspecies solubility comparisons that include modern haloethers. This study aimed to measure hematocrit-adjusted blood:gas anesthetic partition coefficients (λ B:G) for desflurane, sevoflurane, isoflurane, and methoxyflurane in humans and animals. METHODS Whole blood was collected from 20 rats, 8 horses, and 4 each of cats, cattle, humans, dogs, goats, pigs, rabbits, and sheep. Plasma or cell volume was removed to adjust all samples to a packed cell volume of 40%. A single-agent calibration gas headspace was added to blood in a glass syringe and was mixed and equilibrated at 37°C for 2 h. Agent concentrations in the calibration gas and syringe headspace were measured using gas chromatography. Anesthetic solubility in saline, citrate-phosphate-dextrose-adenine, and olive oil were similarly measured. RESULTS Except for goats, all animal species had at least one λ B:G measurement that differed significantly from humans. For each agent, λ B:G positively correlated with serum triglyceride concentrations, but this only explained 25% of interspecies variability. Desflurane was significantly less soluble in blood than sevoflurane in some species (e.g., humans) but not in others (e.g., rabbits). CONCLUSIONS Anesthetic partition coefficients differ significantly between humans and most animals for haloether anesthetics. Because of their similar λ B:G values, goats may be a better animal model for inhaled anesthetic pharmacokinetics in people.
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Terekhov M, Scholz A, Schreiber LM. Measurement of anesthetic uptake kinetics in the brain using (19)F MRI and cross-correlation analysis after pulsed application. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2013; 27:107-11. [PMID: 23760558 DOI: 10.1007/s10334-013-0380-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 04/25/2013] [Accepted: 05/02/2013] [Indexed: 11/29/2022]
Abstract
OBJECT We present a pilot study based on (19)F-MRI to measure fast and slow wash-in and wash-out kinetics of volatile anesthetics in pig brain. METHOD The periodic administration of anesthetics in pulsed mode is used to enhance the sensitivity of the anesthetic concentration detection by (19)F-MRI signal. Temporal correlation analysis allows mapping the kinetics time constants. RESULTS The clear correlation response to anesthetics concentration changes was found in the brain region in comparison with fatty tissues. CONCLUSION The methodology may yield important pharmacological findings on regional effect of the anesthetics in brain and be a step towards human studies.
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Affiliation(s)
- Maxim Terekhov
- Department of Radiology, Section of Medical Physics, Johannes Gutenberg University Medical Center Mainz, Langenbeckstrasse 1, 55131, Mainz, Germany,
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Postoperative 24-hour result of 15-second grip-and-release test correlates with surgical outcome of cervical compression myelopathy. Spine (Phila Pa 1976) 2012; 37:1283-7. [PMID: 22281480 DOI: 10.1097/brs.0b013e31824ac3d4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN A prospective follow-up study to detect the early neurological improvement after decompression surgery and to clarify its correlation with the late neurological outcome in patients with cervical compression myelopathy. OBJECTIVE To reveal the suitability of a simple performance, 15-second grip-and-release test for postoperative neurological recovery in patients with cervical myelopathy. SUMMARY OF BACKGROUND DATA Although various parameters have been advocated as prognostic factors, there still remain arguments against them. Furthermore, neurological status after decompression surgery has been evaluated weekly or monthly in previous studies, but not hourly or daily. To follow the postoperative neurological recovery, we used our original performance test. METHODS Forty-eight patients who were admitted to undergo decompressive laminoplasty for cervical myelopathy were enrolled in the study. Twenty-five patients who were admitted for lumbar spine surgery were used as controls. Subjects were asked to fully grip and release with their right (or left) hand fingers as fast as possible for 15 seconds, which was recorded by a digital camera. And the number of grip-and-release cycles was counted (15-second test) in the recorded video files. RESULTS In the myelopathy group, the number of grip-and-release cycles before surgery and 4 hours, 24 hours, 48 hours, 1 week, and 2 weeks after surgery was 26.7 ± 10.0, 29.7 ± 9.9, 35.0 ± 11.3, 35.1 ± 9.8, 36.2 ± 9.6, and 37.2 ± 10.2, respectively. The number increased steeply after surgery until 24 hours, and the number was 94% after 24 hours of the number recorded 2 weeks after surgery. In the control group, the number of grip-and-release cycles at each time point was 37.9 ± 9.7, 34.7 ± 9.1, 39.2 ± 9.0, 38.5 ± 8.9, 38.9 ± 9.7, and 38.0 ± 9.3, respectively. There was a transient reduction 4 hours after surgery. CONCLUSION Because the number recorded 24 hours after surgery was significantly correlated with both the maximum gain in the number on the 15-second test and the gain in the Japan Orthopaedic Association score, it could be used as a prognostic factor for neurological outcome in patients with cervical myelopathy.
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WIKLUND A, GUSTAVSSON D, EBBERYD A, SUNDMAN E, SCHULTE G, JONSSON FAGERLUND M, ERIKSSON LI. Prolonged attenuation of acetylcholine-induced phosphorylation of extracellular signal-regulated kinase 1/2 following sevoflurane exposure. Acta Anaesthesiol Scand 2012; 56:608-15. [PMID: 22288781 DOI: 10.1111/j.1399-6576.2011.02632.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/30/2011] [Indexed: 01/04/2023]
Abstract
BACKGROUND Volatile anaesthetics are known to affect cholinergic receptors. Perturbation of cholinergic signalling can cause cognitive deficits. In this study, we wanted to evaluate acetylcholine-induced intracellular signalling following sevoflurane exposure. METHODS Pheochromocytoma12 PC12 cells were exposed to 4.6% sevoflurane for 2 h. Subsequently, Western blotting was used to measure acetylcholine-induced phosphorylation of extracellular signal-regulated kinase 1/2 (ERK) 1/2 and basal Protein kinase B (AKT) phosphorylation. RESULTS After exposure, acetylcholine-induced ERK 1/2 phosphorylation was reduced to 58 ± 8% [95% confidence interval (CI): 38-77%, P = 0.003] compared with non-exposed controls. At 30 min after the end of sevoflurane administration [at 0.7% sevoflurane (0.102 mM)], ERK 1/2 phosphorylation remained reduced to 57 ± 7% (95% CI: 39-74%, P = 0.001) and was at 120 min [0.02% (0.003 mM] still reduced to 63 ± 10% (95% CI: 37-88%, P = 0.01), compared with control. At 360 min after exposure, acetylcholine-induced ERK 1/2 phosphorylation had recovered to 98 ± 16% (95% CI: 45-152%, P = 0.98) compared with control. In contrast, immediately after sevoflurane exposure, basal AKT phosphorylation was increased by 228 ± 37% (95% CI: 133-324%, P = 0.02) but had returned to control levels at 30 min after exposure, 172 ± 67% (95% CI: 0-356%, P = 0.34). CONCLUSION Sevoflurane exposure has differential effects on different intracellular signalling pathways. On one hand, we observed a prolonged attenuation of acetylcholine-induced ERK 1/2 phosphorylation that persisted even when sevoflurane concentrations close to detection level. On the other hand, basal AKT phosphorylation was increased twofold during sevoflurane exposure, with a rapid return to baseline levels after exposure. We speculate that the effects on acetylcholine-induced intracellular signalling observed in our in vitro model could be of relevance also for cholinergic signalling in vivo following sevoflurane exposure.
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Affiliation(s)
| | - D. GUSTAVSSON
- Department of Physiology and Pharmacology; Section for Anesthesiology and Intensive Care Medicine; Karolinska Institutet; Stockholm; Sweden
| | - A. EBBERYD
- Department of Physiology and Pharmacology; Section for Anesthesiology and Intensive Care Medicine; Karolinska Institutet; Stockholm; Sweden
| | | | - G. SCHULTE
- Department of Physiology and Pharmacology; Section for Receptor Biology and Signaling; Karolinska Institutet; Stockholm; Sweden
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Ng LJ, Stuhmiller LM, Stuhmiller JH. Incorporation of Acute Dynamic Ventilation Changes into a Standardized Physiologically Based Pharmacokinetic Model. Inhal Toxicol 2008; 19:247-63. [PMID: 17365028 DOI: 10.1080/08958370601067905] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
A seven-compartment physiologically based pharmacokinetic (PBPK) model incorporating a dynamic ventilation response has been developed to predict normalized internal dose from inhalation exposure to a large range of volatile gases. The model uses a common set of physiologic parameters, including standardized ventilation rates and cardiac outputs for rat and human. This standardized model is validated against experimentally measured blood and tissue concentrations for 21 gases. For each of these gases, body-mass-normalized critical internal dose (blood concentration) is established, as calculated using exposure concentration and time duration specified by the lowest observed adverse effect level (LOAEL) or the acute exposure guideline level (AEGL). The dynamic ventilation changes are obtained by combining the standardized PBPK model with the Toxic Gas Assessment Software 2.0 (TGAS-2), a validated acute ventilation response model. The combined TGAS-2P model provides a coupled, transient ventilation and pharmacokinetic response that predicts body mass normalized internal dose that is correlated with deleterious outcomes. The importance of ventilation in pharmacokinetics is illustrated in a simulation of the introduction of Halon 1301 into an environment of fire gases.
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Affiliation(s)
- Laurel J Ng
- Applied Technologies Division, L-3 Communications/Jaycor, San Diego, California, USA.
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Clinically relevant concentration determination of inhaled anesthetics (halothane, isoflurane, sevoflurane, and desflurane) by 19F NMR. Cell Biochem Biophys 2008; 52:31-5. [PMID: 18719861 DOI: 10.1007/s12013-008-9022-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/23/2008] [Indexed: 10/21/2022]
Abstract
Biophysical studies of protein-anesthetic interactions using nuclear magnetic resonance (NMR) spectroscopy are often conducted by the addition of micro amounts of neat inhaled anesthetic which yields much higher than clinically relevant (0.2-0.5 mM) anesthetic concentrations. We report a 19F NMR technique to measure clinically relevant inhaled anesthetic concentrations from saturated aqueous solutions of these anesthetics (halothane, isoflurane, sevoflurane, and desflurane). We use a setup with a 3-mm NMR tube (containing trifluoroacetic acid as standard), coaxially inserted in a 5-mm NMR tube containing anesthetic solution under investigation. All experiments are conducted in a 5-mm NMR probe. We also have provided standard curves for four inhaled anesthetics using NMR technique. The standard curve for each of these anesthetics is helpful in determining the prerequisite amount of aqueous anesthetic solution required to prepare clinically relevant concentrations for protein-anesthetic interaction studies.
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Girgis Y, Frerk CM, Pigott D. Redistribution of halothane and sevoflurane under simulated conditions of acute airway obstruction. Anaesthesia 2001; 56:613-5. [PMID: 11437759 DOI: 10.1046/j.1365-2044.2001.01989.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Forty patients having surgery requiring muscle paralysis and tracheal intubation were randomly allocated to receive either halothane (n = 20) or sevoflurane (n = 20). Following intravenous anaesthesia and tracheal intubation, inhalation induction of anaesthesia was simulated. After attaining an end-tidal anaesthetic concentration of 2 MAC for the respective agent, the airway was obstructed for 3 min. The end-tidal anaesthetic concentration was measured for the first three breaths following the period of airway obstruction. The decrease in alveolar concentration of sevoflurane following 3 min of airway obstruction was found to be significantly greater than that of halothane. We conclude that even if the airway obstructs completely during inhalational induction of general anaesthesia, awakening would be faster with sevoflurane than with halothane.
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Affiliation(s)
- Y Girgis
- Department of Anaesthesia, The Royal Orthopaedic Hospital, Birmingham, UK
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Takeda T, Makita K, Ishikawa S, Kaneda K, Yokoyama K, Amaha K. Uptake and elimination of sevoflurane in rabbit tissues--an in vivo magnetic resonance spectroscopy study. Can J Anaesth 2000; 47:579-84. [PMID: 10875723 DOI: 10.1007/bf03018951] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
PURPOSE Previous pharmacokinetic studies of fluorinated anesthetics using 19F-magnetic resonance spectroscopy (19F-MRS) have focused on the brain. Investigation of other tissues would give more precise information about the pharmacokinetics of inhalational anesthetics. In this study we investigated the pharmacokinetics of uptake and elimination of sevoflurane in brain, liver, muscle, venous blood and arterial blood of rabbits. METHODS Twenty rabbits were examined by 19F-MRS conducted at 4.7 Tesla using a 1-cm-diameter surface coil for brain (n = 4), liver (n = 5) and muscle (n = 5), and a 1.3-cm-diameter surface coil for arterial (n = 3) and venous (n = 3) blood. Sevoflurane, 4% in oxygen, was administered for 120 min, followed by 120 min elimination. RESULTS Both the uptake and elimination kinetics were best fitted by a biexponential curve which was divided into fast and slow components. During the uptake experiment the time required to reach half of the maximum spectroscopic intensity in each tissue was 1.6 min in arterial blood, 4.7 min in liver, 12.2 min in venous blood, 14.4 min in brain and 20.9 min in muscle. During the elimination experiment the time required to reach half maximum intensity was 2.4 min in arterial blood, 6.3 min in liver, 13.4 min in venous blood, 19.6 min in brain and 28.7 min in muscle. CONCLUSIONS Sevoflurane uptake or elimination in the tissues examined followed biexponential kinetics. In this rabbit model, sevoflurane uptake and elimination were fastest in arterial blood, followed, in order, by liver, venous blood, brain and muscle.
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Affiliation(s)
- T Takeda
- Department of Anesthesiology and Critical Care Medicine, Tokyo Medical and Dental University, Japan.
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Soma LR, Tierney WJ, Hogan GK, Satoh N. The Effects of Multiple Administrations of Sevoflurane to Cynomolgus Monkeys. Anesth Analg 1995. [DOI: 10.1213/00000539-199508000-00024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Soma LR, Tierney WJ, Hogan GK, Satoh N. The effects of multiple administrations of sevoflurane to cynomolgus monkeys: clinical pathologic, hematologic, and pathologic study. Anesth Analg 1995; 81:347-52. [PMID: 7618727 DOI: 10.1097/00000539-199508000-00024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The effect of multiple administrations of sevoflurane was evaluated by several measures of toxicity. Cynomolgus monkeys assigned to a control group and three treatment groups were anesthetized with sevoflurane at 1.0, 1.6, and 2.0 times the minimum alveolar anesthetic concentration (MAC) for 3 h/day, 3 days/wk for 8 wk. Reductions in total erythrocyte and leukocyte counts and increases in serum enzymes were the only changes noted. The increases in the serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactic dehydrogenase (LDH), and creatinine kinase (CK), occurred at Week 1 at all three concentrations of sevoflurane. These increases were dose-related, and returned to baseline by Week 2 for 1.0 MAC. All serum enzyme concentrations had returned to baseline by the end of the study. There were no gross pathologic, histopathologic, or ultrastructural differences found in any of the four groups of monkeys. At 2.0 MAC, three deaths occurred. The multiple administrations of 1.0 and 1.6 MAC sevoflurane anesthesia were well tolerated by the monkeys. The techniques of this study did not detect adverse effects from the above enzyme changes.
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Affiliation(s)
- L R Soma
- University of Pennsylvania School of Veterinary Medicine, Kennett Square 19348-1692, USA
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Abstract
We compared the rates of elimination of sevoflurane and halothane in 29 children, aged between one and seven years, undergoing ambulatory anaesthesia. Analgesia was provided by fentanyl and muscle relaxation by atracurium. Anaesthesia was maintained by inhalation of one MAC of either sevoflurane or halothane, based on an equipotent concentration of each agent for the age of the child. Following simultaneous discontinuation of N2O and the inhalational agent, the equation describing N2O washout was identical in the presence of halothane and sevoflurane, showing that there was no effect of the volatile agent on the rate of N2O elimination. The elimination of sevoflurane and N2O give similar types of equations. Halothane elimination gives a logarithmic type of equation, showing a slower release, corresponding to residual tissue content.
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Affiliation(s)
- A Landais
- Department of Anesthesia, Hospital Victor Dupouy, Argenteuil, France
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Abstract
Sevoflurane, a methylethylether halogenated solely with fluorine, is characterized by a low blood/gas solubility (blood/gas partition coefficient = 0.65). This feature allows in a more rapid uptake and elimination than with more soluble agents. MAC is about 2 vol% in young adults and 2.5 vol% in children of more than 6 months of age. It undergoes degradation by soda lime in various components. Among them, compound A (an olefin) produces renal toxicity in rats. Total sevoflurane metabolism represents about 5% of inhaled dose and produces inorganic fluorides. However no renal toxic effects has been reported up to now in animals and in patients. The effects on central nervous and cardiovascular systems are close to those of isoflurane. It decreases cerebral vascular resistances and cerebral oxygen consumption, but does not cause convulsive activity. It decreases myocardial contractility, systolic arterial pressure and systemic vascular resistances, but heart rate remains basically unchanged up to 1 MAC. It does not sensitize the myocardium to catecholamines. It depresses ventilation in a dose-dependent fashion, this effect being more pronounced than that of halothane but less than that of both isoflurane and enflurane. It is not irritant for the airways and has some bronchodilatory effect. In adults, recovery is more rapid than with isoflurane. In children, sevoflurane seems a promising agent owing to its good acceptance for mask induction, as well as its favourable haemodynamic profile. However due to its rapid elimination, analgesic drugs should be administered early enough to decrease the incidence of postoperative pain.
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Affiliation(s)
- I Murat
- Service d'Anesthésie-Réanimation, Hôpital d'Enfants Armand-Trousseau, Paris
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Hawkins RA, Hawkins PA, Mans AM, Viña JR, DeJoseph MR. Optimizing the measurement of regional cerebral glucose consumption with [6-14C]glucose. J Neurosci Methods 1994; 54:49-62. [PMID: 7815819 DOI: 10.1016/0165-0270(94)90159-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
[6-14C]Glucose is used to trace the cerebral metabolic rate of glucose (CMRGlc) in vivo in experiments lasting 5-10 min. Initially 14C is trapped in intermediary metabolite pools. Subsequently 14C is lost as a function of time and metabolic rate, primarily as 14CO2. Experiments were designed to evaluate the rate of 14C lost as 14CO2 or as [14C]lactate from brain labeled with [6-14C]glucose during times up to 15 min. CMRGlc was measured during 5, 7.5, 10 and 15 min in 60 brain areas. At longer times the loss of 14C was reflected by lower apparent values of brain CMRGlc. Arteriovenous measurements across brain revealed no significant loss of [14C]lactate in normal rats or rats with bicuculline-induced seizures. It was concluded that the primary form in which 14C was lost was as 14CO2. As expected, the rate of 14CO2 loss was greater in structures with high metabolic rates. The data were analyzed to determine the parameters necessary to rectify the data so that uniform values of CMRGlc were obtained up to 15 min. Tables were made to predict the degree of 14C loss as well as the 14C-metabolites/[6-14C]glucose ratio as a function of time and metabolic rate. These tables can be used to plan the maximum and minimum experimental times for optimal results.
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Affiliation(s)
- R A Hawkins
- Department of Physiology and Biophysics, University of Health Sciences, Chicago Medical School, IL 60064
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Clonidine premedication for sevoflurane anesthesia in upper abdominal surgery. J Anesth 1994; 8:21-24. [PMID: 28921192 DOI: 10.1007/bf02482747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/1993] [Accepted: 04/11/1993] [Indexed: 10/24/2022]
Abstract
The effects of clonidine as a preanesthetic medication were compared with diazepam on clinical courses of sevoflurane anesthesia in 22 patients undergoing upper abdominal surgery. The patients were divided into two groups of 11 patients each according to preanesthetic medication: atropine 0.5 mg i.m. plus clonidine 0.3 mg p.o., or atropine 0.5 mg i.m. plus diazepam 10 mg p.o. 60-90 min prior to induction of anesthesia. Anesthesia was induced with fentanyl and thiopental, and was maintained with sevoflurane, 0.5%-1.5%, nitrous oxide and oxygen, supplemented with fentanyl, 0.5 μg·kg-1·hr-1. While only one patient needed a vasodilator in the clonidine group for treatment of hypertension, seven patients needed it in the diazepam group. Pain score after extubation was higher in the diazepam group than in the clonidine group. The time when patients responded to verbal command after discontinuation of anesthetics was similar in both groups. Therefore, clonidine pretreatment was useful for sevoflurane anesthesia in upper abdominal surgery.
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Dubois BW, Cherian SF, Evers AS. Volatile anesthetics compete for common binding sites on bovine serum albumin: a 19F-NMR study. Proc Natl Acad Sci U S A 1993; 90:6478-82. [PMID: 8341659 PMCID: PMC46955 DOI: 10.1073/pnas.90.14.6478] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
There is controversy as to the molecular nature of volatile anesthetic target sites. One proposal is that volatile anesthetics bind directly to hydrophobic binding sites on certain sensitive target proteins. Consistent with this hypothesis, we have previously shown that a fluorinated volatile anesthetic, isoflurane, binds saturably [Kd (dissociation constant) = 1.4 +/- 0.2 mM, Bmax = 4.2 +/- 0.3 sites] to fatty acid-displaceable domains on serum albumin. In the current study, we used 19F-NMR T2 relaxation to examine whether other volatile anesthetics bind to the same sites on albumin and, if so, whether they vary in their affinity for these sites. We show that three other fluorinated volatile anesthetics bind with varying affinity to fatty acid-displaceable domains on serum albumin: halothane, Kd = 1.3 +/- 0.2 mM; methoxyflurane, Kd = 2.6 +/- 0.3 mM; and sevoflurane, Kd = 4.5 +/- 0.6 mM. These three anesthetics inhibit isoflurane binding in a competitive manner: halothane, K(i) (inhibition constant) = 1.3 +/- 0.2 mM; methoxyflurane, K(i) = 2.5 +/- 0.4 mM; and sevoflurane, K(i) = 5.4 +/- 0.7 mM--similar to each anesthetic's respective Kd of binding to fatty acid displaceable sites. These results illustrate that a variety of volatile anesthetics can compete for binding to specific sites on a protein.
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Affiliation(s)
- B W Dubois
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110
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