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Mühlemann S, Leandri M, Risberg ÅI, Spadavecchia C. Comparison of Threshold and Tolerance Nociceptive Withdrawal Reflexes in Horses. Animals (Basel) 2021; 11:ani11123380. [PMID: 34944157 PMCID: PMC8698093 DOI: 10.3390/ani11123380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 11/23/2021] [Accepted: 11/25/2021] [Indexed: 11/30/2022] Open
Abstract
Simple Summary Nociception is the physiological basis of the complex experience of pain. An established model for its quantification in equine studies is based on the nociceptive withdrawal reflex evoked by electrical stimulation of a sensory nerve. The reflex is recorded via electromyography and it is common to determine the threshold at which a nociceptive-specific reflex activity can be observed. In the present study, the classical methodology was expanded for a deeper understanding of the physiology of nociceptive reflexes in horses. First, for each individual horse, a threshold was determined as the minimal stimulation intensity able to evoke a nociceptive withdrawal reflex. Second, the stimulation intensity was stepwise increased up to tolerance, which was defined as the stimulus that is able to elicit the maximal tolerable behavioral reaction. The characteristics of the reflex activity on the electromyographic records were compared for threshold and tolerance stimulation intensities. At tolerance, the reflex became faster and wider than at threshold, indicating that either a spinal summation mechanism or the recruitment of faster sensory fibers occurs in response to high-intensity noxious stimuli. A novel endpoint (i.e., tolerance) can now be considered when applying the nociceptive withdrawal reflex model in equine studies. Abstract The nociceptive withdrawal reflex (NWR) is used to investigate nociception in horses. The NWR threshold is a classical model endpoint. The aims of this study were to determine NWR tolerance and to compare threshold and tolerance reflexes in horses. In 12 horses, the NWR was evoked through electrical stimulation of the digital nerve and recorded via electromyography from the deltoid. Behavioral reactions were scored from 0 to 5 (tolerance). First, the individual NWR threshold was defined, then stimulation intensity was increased to tolerance. The median NWR threshold was 7.0 mA, whereas NWR tolerance was 10.7 mA. Upon visual inspection of the records, two main reflex components R1 (median latency 44 ms) and R2 (median latency 81 ms) were identified at threshold. Increasing stimulation intensity to tolerance led to a significant increase in the amplitude and duration of R1 and R2, whereas their latency decreased. At tolerance, a single burst of early, high-amplitude reflex activity, with a median latency of 39 ms, was detected in 15 out of 23 stimulations (65%). The results of this study suggest that (1) it is feasible to determine NWR tolerance in horses and (2) high-intensity stimuli initiate ultrafast bursts of reflex activity, which is well known in practice and has now been quantified using the NWR model.
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Affiliation(s)
- Selina Mühlemann
- Department of Clinical Veterinary Medicine, Anaesthesia Section, Vetsuisse Faculty Bern, 3012 Bern, Switzerland;
| | - Massimo Leandri
- Department of Neuroscience, University of Genova, 16132 Genova, Italy;
| | - Åse Ingvild Risberg
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 1433 Ås, Norway;
| | - Claudia Spadavecchia
- Department of Clinical Veterinary Medicine, Anaesthesia Section, Vetsuisse Faculty Bern, 3012 Bern, Switzerland;
- Correspondence: ; Tel.: +41-31-684-29-57
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ISOFLURANE ANESTHESIA IN BUDWING PRAYING MANTISES ( PARASPHENDALE AGRIONINA). J Zoo Wildl Med 2021; 52:1013-1017. [PMID: 34687518 DOI: 10.1638/2020-0195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/06/2021] [Indexed: 11/21/2022] Open
Abstract
Praying mantises have gained increasing popularity as pets and may be anesthetized to allow morphological identification and clinical procedures. The aim of this study was to evaluate the effects and anesthetic-related complications of isoflurane in oxygen in 15 client-owned budwing mantises (Parasphendale agrionina) undergoing photographic identification. Each mantis was placed in a self-constructed anesthetic chamber and exposed to a mixture of approximately 5% isoflurane in oxygen until anesthetic induction was achieved. Time to anesthetic induction, time to recovery from anesthesia, and quality of anesthesia based on scoring of righting reflex, front legs withdrawal, and muscular tone, were evaluated and recorded, as well as the occurrence of undesired effects. In most mantises, immobility, loss of righting reflex, and myorelaxation were achieved within minutes after the beginning of isoflurane exposure and lasted a time sufficient to allow completion of the procedure. However, mantises aged ≥12 mo had longer time to anesthetic induction (4.3 ± 0.6 m), as well as shorter time to recovery (19.0 ± 8.0 m), than mantises aged <12 mo (0.8 ± 0.4 and 30.0 ± 15.0; P < 0.05). Complications were not observed, and all mantises were returned to their owner on the same evening.
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Morath-Huss U, Drögemüller C, Stoffel M, Precht C, Zanolari P, Spadavecchia C. Polymelia in a chimeric Simmental calf: nociceptive withdrawal reflex, anaesthetic and analgesic management, anatomic and genetic analysis. BMC Vet Res 2019; 15:102. [PMID: 30922306 PMCID: PMC6440010 DOI: 10.1186/s12917-019-1846-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 03/18/2019] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND Polymelia is a congenital defect characterized by one or more supernumerary legs. The genetics and aetiology of this condition in cattle have not yet been thoroughly investigated even though several case reports do exist. The model of the nociceptive withdrawal reflex (NWR) has been characterized in several species to study spinal nociceptive processing. It is a polysynaptic spinal reflex that can be elicited by noxious electrical stimulation and recorded by electromyography. Thorough nociceptive examination and preventive analgesic management has not yet been an aspect in the perioperative management of polymelia cases. CASE PRESENTATION A 4-month-old female Simmental calf was presented with notomelia. The animal was in good health and showed no neurologic deficiencies. Preoperatively, computed tomography was performed to gain more detailed anatomical information. To evaluate the sensitivity of the accessory limb, NWR testing was performed and revealed a connection of the afferent reflex pathway of the accessory limb to the efferent of the normal limb. The accessory limb was surgically removed under general anaesthesia. Intensive care included multimodal pain therapy adapted to the pain intensity scored during regular pain assessment. A gross anatomical dissection as well as a genetic analysis of the accessory limb were performed postoperatively. The calf was identified as a chimera. CONCLUSION This calf was successfully relieved of its accessory limb. Chimerism has not been described in the congenital defect polymelia. As the accessory limb was pain sensitive and a common nociceptive reflex pathway was identified, thorough perioperative pain management was performed with the intention to prevent chronic neuropathic pain development.
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Affiliation(s)
- Ute Morath-Huss
- Department of Veterinary Clinical Science, Anaesthesiology and Pain Therapy Division, Vetsuisse Faculty, University of Bern, Länggassstrasse 124, 3012 Bern, Switzerland
| | - Cord Drögemüller
- Institute of Genetics, Vetsuisse Faculty, University of Bern, 3001 Bern, Switzerland
| | - Michael Stoffel
- Division of Veterinary Anatomy, Department of Clinical Research and VPH, Vetsuisse Faculty, University of Bern, POB 3350, 3001 Bern, Switzerland
| | - Christina Precht
- Clinical Radiology, Department of Clinical Veterinary Medicine, University of Bern, Länggassstrasse124, 3012 Bern, Switzerland
| | - Patrik Zanolari
- Clinic for Ruminants, Vetsuisse Faculty, University of Bern, Bremgartenstrasse 12, 109a, 3012 Bern, Switzerland
| | - Claudia Spadavecchia
- Department of Veterinary Clinical Science, Anaesthesiology and Pain Therapy Division, Vetsuisse Faculty, University of Bern, Länggassstrasse 124, 3012 Bern, Switzerland
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Lervik A, Raszplewicz J, Ranheim B, Solbak S, Toverud SF, Haga HA. Dexmedetomidine or fentanyl? Cardiovascular stability and analgesia during propofol-ketamine total intravenous anaesthesia in experimental pigs. Vet Anaesth Analg 2018; 45:295-308. [DOI: 10.1016/j.vaa.2017.08.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 07/13/2017] [Accepted: 08/29/2017] [Indexed: 10/18/2022]
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Hunt J, Murrell J, Knazovicky D, Harris J, Kelly S, Knowles TG, Lascelles BDX. Alfaxalone Anaesthesia Facilitates Electrophysiological Recordings of Nociceptive Withdrawal Reflexes in Dogs (Canis familiaris). PLoS One 2016; 11:e0158990. [PMID: 27433936 PMCID: PMC4951135 DOI: 10.1371/journal.pone.0158990] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Accepted: 06/25/2016] [Indexed: 12/02/2022] Open
Abstract
Naturally occurring canine osteoarthritis represents a welfare issue for affected dogs (Canis familiaris), but is also considered very similar to human osteoarthritis and has therefore been proposed as a model of disease in humans. Central sensitisation is recognized in human osteoarthritis sufferers but identification in dogs is challenging. Electromyographic measurement of responses to nociceptive stimulation represents a potential means of investigating alterations in central nociceptive processing, and has been evaluated in conscious experimental dogs, but is likely to be aversive. Development of a suitable anaesthetic protocol in experimental dogs, which facilitated electrophysiological nociceptive withdrawal reflex assessment, may increase the acceptability of using the technique in owned dogs with naturally occurring osteoarthritis. Seven purpose bred male hound dogs underwent electromyographic recording sessions in each of three states: acepromazine sedation, alfaxalone sedation, and alfaxalone anaesthesia. Electromyographic responses to escalating mechanical and electrical, and repeated electrical, stimuli were recorded. Subsequently the integral of both early and late rectified responses was calculated. Natural logarithms of the integral values were analysed within and between the three states using multi level modeling. Alfaxalone increased nociceptive thresholds and decreased the magnitude of recorded responses, but characteristics of increasing responses with increasing stimulus magnitude were preserved. Behavioural signs of anxiety were noted in two out of seven dogs during recordings in the acepromazine sedated state. There were few significant differences in response magnitude or nociceptive threshold between the two alfaxalone states. Following acepromazine premedication, induction of anaesthesia with 1–2 mg kg-1 alfaxalone, followed by a continuous rate infusion in the range 0.075–0.1 mg kg-1 min-1 produced suitable conditions to enable assessment of spinal nociceptive processing in dogs, without subjecting them to potentially aversive experiences. This methodology may be appropriate for obtaining electrophysiological nociceptive withdrawal reflex data in client-owned dogs with naturally occurring osteoarthritis.
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Affiliation(s)
- James Hunt
- School of Veterinary Sciences, University of Bristol, Bristol, United Kingdom
| | - Jo Murrell
- School of Veterinary Sciences, University of Bristol, Bristol, United Kingdom
| | - David Knazovicky
- Comparative Pain Research Laboratory, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, United States of America
| | - John Harris
- Division of Animal Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, United Kingdom
| | - Sara Kelly
- Division of Animal Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, United Kingdom
| | - Toby G. Knowles
- School of Veterinary Sciences, University of Bristol, Bristol, United Kingdom
| | - B. Duncan X. Lascelles
- Comparative Pain Research Laboratory, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, United States of America
- Center for Pain Research and Innovation, UNC School of Dentistry, Chapel Hill, North Carolina, United States of America
- Comparative Medicine Institute, North Carolina State University, Raleigh, North Carolina, United States of America
- * E-mail:
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Spadavecchia C, Haga H, Ranheim B. Concentration-dependent isoflurane effects on withdrawal reflexes in pigs and the role of the stimulation paradigm. Vet J 2012; 194:375-9. [DOI: 10.1016/j.tvjl.2012.04.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Revised: 04/17/2012] [Accepted: 04/18/2012] [Indexed: 10/28/2022]
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Lervik A, Haga HA, Ranheim B, Spadavecchia C. The influence of a continuous rate infusion of dexmedetomidine on the nociceptive withdrawal reflex and temporal summation during isoflurane anaesthesia in dogs. Vet Anaesth Analg 2012; 39:414-25. [PMID: 22413770 DOI: 10.1111/j.1467-2995.2012.00713.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To examine the influence of a low dose dexmedetomidine infusion on the nociceptive withdrawal reflex and temporal summation in dogs during isoflurane anaesthesia. STUDY DESIGN Prospective experimental blinded cross-over study. ANIMALS Eight healthy mixed breed dogs, body weight Mean ± SD 26.5 ± 8.4 kg and age 25 ± 16 months. METHODS Anaesthesia was induced with propofol and maintained with isoflurane (Fe'ISO 1.3%) delivered in oxygen and air. After stabilization, baseline recordings (time 0) were obtained, then a dexmedetomidine bolus (1 μg kg(-1) IV) followed by a continuous rate infusion (1 μg kg(-1) hour(-1)) or saline placebo were administered. At times 10, 30 and 60 minutes after the initial bolus, electrical stimulations of increasing intensity were applied over the lateral plantar digital nerve, and administered both as single and as repeated stimuli. The resulting reflex responses were recorded using electromyography. Data were analysed using a multivariable linear regression model and a Kruskal Wallis test for single stimulation data, and repeated measures anova and paired t-test for repeated stimulation data. RESULTS The AUC for the stimulus-response curves after single stimulation were similar for both treatments at time 0. At times 10, 30 and 60 the AUCs for the stimulus-response curves were significantly lower with dexmedetomidine treatment than with placebo. Temporal summation was evident in both treatments at times 0, 10, 30 and 60 starting from a stimulation intensity of 10 mA. The magnitude of temporal summation was smaller in dexmedetomidine than in placebo treated dogs at time 10, 30 and 60, but not at time 0. CONCLUSIONS During isoflurane anaesthesia, low dose dexmedetomidine suppresses the nociceptive reflex responses after single and repeated electrical stimulation. CLINICAL RELEVANCE This experimental study confirms previous reports on its peri-operative efficacy under clinical conditions, and further indicates that dexmedetomidine might reduce the risk of post-operative chronic pain development.
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Affiliation(s)
- Andreas Lervik
- Department of Companion Animal Clinical Sciences, Norwegian School of Veterinary Science, Oslo, Norway.
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Levionnois O, Mevissen M, Thormann W, Spadavecchia C. Assessing the efficiency of a pharmacokinetic-based algorithm for target-controlled infusion of ketamine in ponies. Res Vet Sci 2010; 88:512-8. [DOI: 10.1016/j.rvsc.2009.12.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2009] [Revised: 12/02/2009] [Accepted: 12/06/2009] [Indexed: 10/20/2022]
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Spadavecchia C, Levionnois O, Kronen P, Andersen OK. The effects of isoflurane minimum alveolar concentration on withdrawal reflex activity evoked by repeated transcutaneous electrical stimulation in ponies. Vet J 2010; 183:337-44. [DOI: 10.1016/j.tvjl.2008.12.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2008] [Revised: 12/22/2008] [Accepted: 12/22/2008] [Indexed: 11/25/2022]
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Effect of ketamine on the limb withdrawal reflex evoked by transcutaneous electrical stimulation in ponies anaesthetised with isoflurane. Vet J 2009; 186:304-11. [PMID: 19748807 DOI: 10.1016/j.tvjl.2009.08.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2009] [Revised: 06/15/2009] [Accepted: 08/15/2009] [Indexed: 11/24/2022]
Abstract
The purpose of this study was to evaluate the anti-nociceptive activity of ketamine and isoflurane in horses using a limb withdrawal reflex (WR) model. Single and repeated stimulations were applied to the digital nerve of the left forelimb in ponies anaesthetised with isoflurane before, during and after intravenous administration of racemic ketamine. Surface electromyographic activity was recorded from the deltoid muscle. Higher stimulation intensity was required to evoke a reflex during ketamine administration. Furthermore, the amplitudes of response to stimulations were significantly and dose-dependently depressed and a flattening of the stimulus-response curves was observed. The reflex activity recovered partially once the ketamine infusion finished. The results demonstrated that the limb WR can be used to quantify the temporal effect of ketamine on the sensory-motor processing in ponies anaesthetised with isoflurane.
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Yan S, Dai TJ, Zeng YM. Nicotinic acetylcholine receptors mediate the hypnotic and analgesic effects of emulsified inhalation anesthetics. Fundam Clin Pharmacol 2009; 23:235-40. [DOI: 10.1111/j.1472-8206.2008.00657.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Hang LH, Shao DH, Yang YH, Dai TJ, Zeng YM. SPINAL ?-AMINO-3-HYDROXY-5-METHYL-4-ISOXAZOLEPROPIONIC ACID RECEPTORS MAY MEDIATE THE ANALGESIC EFFECTS OF EMULSIFIED HALOGENATED ANAESTHETICS. Clin Exp Pharmacol Physiol 2007; 34:1121-5. [PMID: 17880364 DOI: 10.1111/j.1440-1681.2007.04690.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
1. The present study was designed to investigate the relationship between spinal cord alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors and the analgesic effects of emulsified halogenated anaesthetics. 2. After having established the mouse model of analgesia by intraperitoneal or subcutaneous injections of appropriate doses of emulsified enflurane, isoflurane or sevoflurane, we injected different doses of AMPA intrathecally and observed effects on the pain threshold using the hot-plate and acetic acid-induced writhing tests. 3. The results showed that intrathecal injection of AMPA (0.25, 0.5 and 1.0 ng) did not affect the pain threshold on the hot-plate test or the writhing times in conscious mice. In contrast, AMPA (0.25, 0.5 and 1.0 ng intrathecally) significantly and dose-dependently decreased the pain threshold on the hot-plate test and increased the writhing times in mice treated with emulsified anaesthetics. 4. These results suggest that spinal AMPA receptors may be important targets for the analgesic effects of emulsified enflurane, isoflurane and sevoflurane.
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MESH Headings
- Acetic Acid
- Analgesics/chemistry
- Analgesics/pharmacology
- Analgesics/therapeutic use
- Anesthetics, Inhalation/chemistry
- Anesthetics, Inhalation/pharmacology
- Anesthetics, Inhalation/therapeutic use
- Animals
- Behavior, Animal/drug effects
- Disease Models, Animal
- Emulsions
- Enflurane/pharmacology
- Hot Temperature
- Hydrocarbons, Halogenated/chemistry
- Hydrocarbons, Halogenated/pharmacology
- Hydrocarbons, Halogenated/therapeutic use
- Injections, Spinal
- Isoflurane/pharmacology
- Methyl Ethers/pharmacology
- Mice
- Pain/chemically induced
- Pain/metabolism
- Pain/physiopathology
- Pain/prevention & control
- Pain Measurement
- Pain Threshold/drug effects
- Receptors, AMPA/drug effects
- Receptors, AMPA/metabolism
- Sevoflurane
- Spinal Cord/drug effects
- Spinal Cord/metabolism
- Time Factors
- alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid/administration & dosage
- alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid/metabolism
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Affiliation(s)
- Li-Hua Hang
- The Affiliated People's Hospital of Jiangsu University, The First People's Hospital of Zhenjiang, Zhenjiang, China
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Larenza MP, Landoni MF, Levionnois OL, Knobloch M, Kronen PW, Theurillat R, Schatzmann U, Thormann W. Stereoselective pharmacokinetics of ketamine and norketamine after racemic ketamine or S-ketamine administration during isoflurane anaesthesia in Shetland ponies. Br J Anaesth 2007; 98:204-12. [PMID: 17218377 DOI: 10.1093/bja/ael336] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND The arterial pharmacokinetics of ketamine and norketamine enantiomers after racemic ketamine or S-ketamine i.v. administration were evaluated in seven gelding ponies in a crossover study (2-month interval). METHODS Anaesthesia was induced with isoflurane in oxygen via a face-mask and then maintained at each pony's individual MAC. Racemic ketamine (2.2 mg kg(-1)) or S-ketamine (1.1 mg kg(-1)) was injected in the right jugular vein. Blood samples were collected from the right carotid artery before and at 1, 2, 4, 8, 16, 32, 64, and 128 min after ketamine administration. Ketamine and norketamine enantiomer plasma concentrations were determined by capillary electrophoresis. Individual R-ketamine and S-ketamine concentration vs time curves were analysed by non-linear least square regression two-compartment model analysis using PCNonlin. Plasma disposition curves for R-norketamine and S-norketamine were described by estimating AUC, C(max), and T(max). Pulse rate (PR), respiratory rate (R(f)), tidal volume (V(T)), minute volume ventilation (V(E)), end-tidal partial pressure of carbon dioxide (PE'(CO(2))), and mean arterial blood pressure (MAP) were also evaluated. RESULTS The pharmacokinetic parameters of S- and R-ketamine administered in the racemic mixture or S-ketamine administered separately did not differ significantly. Statistically significant higher AUC and C(max) were found for S-norketamine compared with R-norketamine in the racemic group. Overall, R(f), V(E), PE'(CO(2)), and MAP were significantly higher in the racemic group, whereas PR was higher in the S-ketamine group. CONCLUSIONS Norketamine enantiomers showed different pharmacokinetic profiles after single i.v. administration of racemic ketamine in ponies anaesthetised with isoflurane in oxygen (1 MAC). Cardiopulmonary variables require further investigation.
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MESH Headings
- Anesthesia, General/methods
- Anesthesia, General/veterinary
- Anesthetics, Combined/administration & dosage
- Anesthetics, Combined/blood
- Anesthetics, Combined/pharmacology
- Anesthetics, Dissociative/administration & dosage
- Anesthetics, Dissociative/blood
- Anesthetics, Inhalation
- Animals
- Blood Pressure/drug effects
- Cross-Over Studies
- Drug Administration Schedule
- Electrocardiography
- Heart Rate/drug effects
- Horses/blood
- Isoflurane
- Ketamine/administration & dosage
- Ketamine/analogs & derivatives
- Ketamine/blood
- Male
- Monitoring, Intraoperative/instrumentation
- Monitoring, Intraoperative/methods
- Monitoring, Intraoperative/veterinary
- Stereoisomerism
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Affiliation(s)
- M P Larenza
- Anaesthesiology Section, Department of Clinical Veterinary Medicine, Vetsuisse Faculty, Bern, Switzerland
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