Pharmacokinetics and clinical effects of xylazine and dexmedetomidine in horses recovering from isoflurane anesthesia

Guedes, Alonso; Knych, Heather K.; Tucker, Laura; Almeida, Daniel; Baldo, Caroline Floreoto; Wendt‐Hornickle, Erin; Allweiler, Sandra

doi:10.1111/jvp.12855

Cited by 8 publications

(16 citation statements)

References 24 publications

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“…In horses, all alpha-2 adrenergic agonists available for administration to horses have been used for balanced anaesthesia due to their sedation and potent analgesic effects [ 22 ]. Although not currently registered for horses in countries such as Europe, Australia and the United States, medetomidine, including its active enantiomer dexmedetomidine, have been shown to be short-acting, have high clearance rates and undergo rapid distribution, compared to other alpha-2 agonists such as xylazine, making them more suitable for intravenous infusions [ 23 , 24 , 25 , 26 , 27 ]. This is in addition to producing similar post-anaesthetic recovery times and recovery qualities in horses as compared to xylazine [ 24 , 27 ].…”

Section: Discussionmentioning

confidence: 99%

“…Although not currently registered for horses in countries such as Europe, Australia and the United States, medetomidine, including its active enantiomer dexmedetomidine, have been shown to be short-acting, have high clearance rates and undergo rapid distribution, compared to other alpha-2 agonists such as xylazine, making them more suitable for intravenous infusions [ 23 , 24 , 25 , 26 , 27 ]. This is in addition to producing similar post-anaesthetic recovery times and recovery qualities in horses as compared to xylazine [ 24 , 27 ]. These pharmacokinetic properties of medetomidine led to its choice as both a premedication and co-infusion agent in this study.…”

Section: Discussionmentioning

confidence: 99%

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Total Intravenous Anaesthesia with Ketamine, Medetomidine and Midazolam as Part of a Balanced Anaesthesia Technique in Horses Undergoing Castration

Cunneen

Pratt

Perkins

et al. 2021

Veterinary Sciences

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To evaluate the use of ketamine-medetomidine-midazolam total intravenous infusion as part of a balanced anaesthetic technique for surgical castration in horses. Five healthy Standardbred cross colts were premedicated with IV acepromazine (0.01–0.02 mg/kg), medetomidine (7 µg/kg) and methadone (0.1 mg/kg) and anaesthesia induced with IV ketamine (2.2 mg/kg) and midazolam (0.06 mg/kg). Horses were anaesthetised for 40 min with an IV infusion of ketamine (3 mg/kg/h), medetomidine (5 µg/kg/h) and midazolam (0.1 mg/kg/h) while routine surgical castration was performed. Cardiorespiratory variables, arterial blood gases, and anaesthetic depth were assessed at 5 to 10 min intervals. Post-anaesthesia recovery times were recorded, and the quality of the recovery period was assessed. The anaesthetic period and surgical conditions were acceptable with good muscle relaxation and no additional anaesthetic required. The median (range) time from cessation of the infusion to endotracheal tube extubation, head lift and sternal recumbency were 17.2 (7–35) min, 25 (18.9–53) min and 28.1 (23–54) min, respectively. The quality of anaesthetic recovery was good, with horses standing 31.9 (28–61) min after the infusion was ceased. During anaesthesia, physiological variables, presented as a range of median values for each time point were: heart rate 37–44 beats/min, mean arterial pressure 107–119 mmHg, respiratory rate 6–13 breaths/min, arterial partial pressure of oxygen 88–126 mmHg, arterial partial pressure of carbon dioxide 52–57 mmHg and pH 7.36–7.39. In conclusion, the co-administration of midazolam, ketamine and medetomidine as in IV infusion, when used as part of a balanced anaesthetic technique, was suitable for short term anaesthesia in horses undergoing castration.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Total Intravenous Anaesthesia with Ketamine, Medetomidine and Midazolam as Part of a Balanced Anaesthesia Technique in Horses Undergoing Castration

Cunneen

Pratt

Perkins

et al. 2021

Veterinary Sciences

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“…Eighteen publications fell into this category [299][300][301][302][303][304][305][306][307][308][309][310][311][312][313][314][315][316]. Most of the studies were published after the year 2000 and the main inhalant agent used was isoflurane, followed by sevoflurane.…”

Section: Drugs Before/during Recoverymentioning

confidence: 99%

“…Sedation with alpha2-adrenergic agonists improves the recovery quality [302][303][304], an effect that seems to be dose-dependent [302,311]. There is no clear evidence which alpha2-adrenergic agonist is the best [307,314,315]. However, Bienert et al, (2003) and Woodhouse et al, (2013) showed a benefit of romifidine over xylazine [304,309].…”

Section: Drugs Before/during Recoverymentioning

confidence: 99%

“…305] (8) Effect of administration of propofol and xylazine hydrochloride on recovery of horses after four hours of anesthesia with desflurane[306] (9) Comparison of the effects of xylazine and romifidine administered perioperatively on the recovery of anesthetized horses[307] (10) Evaluation of infusions of xylazine with ketamine or propofol to modulate recovery following sevoflurane anesthesia in horses[308] (11) Effects of postanesthetic sedation with romifidine or xylazine on quality of recovery from isoflurane anesthesia in horses[309] (12) Assessment of unassisted recovery from repeated general isoflurane anesthesia in horses following post-anesthetic administration of xylazine or acepromazine or a combination of xylazine and ketamine[310] (13) Effect of postoperative xylazine administration on cardiopulmonary function and recovery quality after isoflurane anesthesia in horses[311] (14) Recovery from desflurane anesthesia in horses with and without post-anesthetic xylazine[312] (15) Comparison between the effects of postanesthetic xylazine and dexmedetomidine on characteristics of recovery from sevoflurane anesthesia in horses[313] (16) Pharmacokinetics and clinical effects of xylazine and dexmedetomidine in horses recovering from isoflurane anesthesia[314] (17) Recovery quality following a single post-anaesthetic dose of dexmedetomidine or romifidine in sevoflurane anaesthetised horses[315] (18) The effects of flumazenil on ventilatory and recovery characteristics in horses following midazolam-ketamine induction and isoflurane anaesthesia[316] drugs before/during recovery publications = 18 LoE: level of evidence.…”

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confidence: 99%

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Recovery after General Anaesthesia in Adult Horses: A Structured Summary of the Literature

Gozalo-Marcilla

Ringer

2021

Animals

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Recovery remains the most dangerous phase of general anaesthesia in horses. The objective of this publication was to perform a structured literature review including levels of evidence (LoE) of each study with the keywords “recovery anaesthesia horse”, entered at once, in the search browsers PubMed and Web of Science. The two authors independently evaluated each candidate article. A final list with 444 articles was obtained on 5 April 2021, classified as: 41 “narrative reviews/expert opinions”, 16 “retrospective outcome studies”, 5 “surveys”, 59 “premedication/sedation and induction drugs”, 27 “maintenance with inhalant agents”, 55 “maintenance with total intravenous anaesthesia (TIVA)”, 3 “TIVA versus inhalants”, 56 “maintenance with partial intravenous anaesthesia (PIVA)”, 27 “other drugs used during maintenance”, 18 “drugs before/during recovery”, 18 “recovery systems”, 21 “respiratory system in recovery”, 41 “other factors”, 51 “case series/reports” and 6 “systems to score recoveries”. Of them, 167 were LoE 1, 36 LoE 2, 33 LoE 3, 110 LoE 4, 90 LoE 5 and 8 could not be classified based on the available abstract. This review can be used as an up-to-date compilation of the literature about recovery after general anaesthesia in adult horses that tried to minimise the bias inherent to narrative reviews.

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Cardiopulmonary function and intestinal blood flow in anaesthetised, experimentally endotoxaemic horses given a constant rate infusion of dexmedetomidine

Hector

Rezende

Nelson

et al. 2021

Equine Veterinary Journal

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Background Endotoxaemia causes untoward inflammatory‐mediated effects that might be attenuated by dexmedetomidine. Objectives To evaluate the effects of a dexmedetomidine intravenous (IV) infusion on systemic and intestinal haemodynamics and arterial blood gas values in sevoflurane‐anaesthetised horses administered Escherichia coli O55:B5 lipopolysaccharides (LPS). Study design Randomised controlled in vivo experiment. Methods A total of 13 horses weighing 456 ± 86 kg (mean ± standard deviation) and aged 13.9 ± 9.0 years donated for euthanasia underwent ventral midline celiotomy using sevoflurane anaesthesia. Baseline physiological variables were recorded after a 90‐minute equilibration period. All horses were given 0.1 mcg/kg bwt LPS IV. Horses were randomly assigned to no further treatment (group LPS; seven horses) or IV administration of dexmedetomidine (loading dose 1.75 mcg/kg bwt followed by 1.75 mcg/kg bwt/h; group LPS–Dex; six horses) with concurrent target sevoflurane dose reduction of 50%. Cardiac index (CI; thermodilution), intestinal blood flow, arterial blood parameters and plasma dexmedetomidine concentration measurements were recorded every 30 minutes until euthanasia at 390 minutes. Data were compared between and within groups to baseline using a mixed model analysis (significance P < .05). Results In LPS‐Dex horses, intestinal blood flow and CI were transiently decreased after the dexmedetomidine loading dose, but no significant differences were found compared with baseline during the infusion. Sevoflurane dose was reliably reduced by approximately 40%. Significant differences were identified in creatinine (115 umol/L LPS‐Dex; 195 umol/L LPS), bicarbonate (29.7 mmol/L LPS‐Dex; 23 mmol/L LPS) and base excess (2.0 mmol/L LPS‐Dex; −5.3 mmol/L LPS). Dexmedetomidine plasma concentrations were highest after the loading dose and stable during infusion dosing. Main limitations Experimental conditions are not reflective of clinical colic management. Conclusions A dexmedetomidine infusion with sevoflurane dose reduction attenuated some deleterious changes in anaesthetised horses administered LPS without sustained negative cardiovascular effects and may be beneficial during colic surgery.

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Pharmacokinetics and clinical effects of xylazine and dexmedetomidine in horses recovering from isoflurane anesthesia

Cited by 8 publications

References 24 publications

Total Intravenous Anaesthesia with Ketamine, Medetomidine and Midazolam as Part of a Balanced Anaesthesia Technique in Horses Undergoing Castration

Total Intravenous Anaesthesia with Ketamine, Medetomidine and Midazolam as Part of a Balanced Anaesthesia Technique in Horses Undergoing Castration

Recovery after General Anaesthesia in Adult Horses: A Structured Summary of the Literature

Cardiopulmonary function and intestinal blood flow in anaesthetised, experimentally endotoxaemic horses given a constant rate infusion of dexmedetomidine

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