Biomaterial Database

Plasma concentrations at two dexmedetomidine constant rate infusions in isoflurane anaesthetized horses: a clinical study. 2019

Vanessa Bettembourg, and Daniela Dulgheriu, and Henning Andreas Haga

Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway. Electronic address: vanessa.bettembourg@nmbu.no.

OBJECTIVE To determine dexmedetomidine plasma concentrations at two infusion rates in isoflurane anaesthetized horses and compare cardiovascular effects and anaesthetic recovery between treatments. METHODS Prospective, randomized, masked clinical study. METHODS Healthy, adult, client-owned, non-food producing horses presented for castration. METHODS Premedication consisted of acepromazine, romifidine and morphine, and anaesthesia was induced with ketamine and midazolam. The horses were randomized to receive dexmedetomidine 0.5 μg kg-1 hour-1 (treatment DL, n = 7) or 1.75 μg kg-1 hour-1 (treatment DH, n = 7) for 90 minutes of isoflurane anaesthesia at an end-tidal concentration of 1.2%. Venous plasma concentrations were determined with liquid chromatography-electrospray-ionization-tandem mass spectrometry. Jugular venous and arterial blood was sampled for blood gas analysis at the start and end of the infusion. Changes in cardiovascular variables from the start to the end of the infusion, and recovery parameters were statistically compared between treatments. RESULTS Fourteen male horses, 2-6 years old, 325-536 kg were included. Mean ± standard deviation dexmedetomidine plasma concentrations at 30, 60 and 90 minutes with treatment DL were 0.22 ± 0.05, 0.29 ± 0.07 and 0.33 ± 0.08 ng mL-1, and with treatment DH were 0.65 ± 0.11, 0.89 ± 0.10 and 1.01 ± 0.10 ng mL-1. The 95% confidence interval for change minute-1 in dexmedetomidine plasma concentrations between 75 and 90 minutes was 0-1% for both treatments. With treatment DH, the heart rate decreased significantly more from the beginning to the end of the infusion compared to DL (p = 0.043). No other significant differences were found between treatments in cardiovascular or recovery parameters. CONCLUSIONS Infusion of dexmedetomidine in isoflurane anaesthetized horses resulted in plasma concentrations with low variation at both infusion rates, approaching stable levels after 75 minutes of infusion. No differences of clinical importance were found when comparing cardiovascular variables and quality of recovery between treatments.

UI	MeSH Term	Description	Entries
D006993	Hypnotics and Sedatives	Drugs used to induce drowsiness or sleep or to reduce psychological excitement or anxiety.	Hypnotic,Sedative,Sedative and Hypnotic,Sedatives,Hypnotic Effect,Hypnotic Effects,Hypnotics,Sedative Effect,Sedative Effects,Sedatives and Hypnotics,Effect, Hypnotic,Effect, Sedative,Effects, Hypnotic,Effects, Sedative,Hypnotic and Sedative
D007530	Isoflurane	A stable, non-explosive inhalation anesthetic, relatively free from significant side effects.
D008297	Male		Males
D009919	Orchiectomy	The surgical removal of one or both testicles.	Castration, Male,Orchidectomy,Castrations, Male,Male Castration,Male Castrations,Orchidectomies,Orchiectomies
D011446	Prospective Studies	Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.	Prospective Study,Studies, Prospective,Study, Prospective
D006736	Horses	Large, hoofed mammals of the family EQUIDAE. Horses are active day and night with most of the day spent seeking and consuming food. Feeding peaks occur in the early morning and late afternoon, and there are several daily periods of rest.	Equus caballus,Equus przewalskii,Horse, Domestic,Domestic Horse,Domestic Horses,Horse,Horses, Domestic
D000758	Anesthesia	A state characterized by loss of feeling or sensation. This depression of nerve function is usually the result of pharmacologic action and is induced to allow performance of surgery or other painful procedures.
D000762	Anesthesia Recovery Period	The period of emergence from general anesthesia, where different elements of consciousness return at different rates.	Recovery Period, Anesthesia,Anesthesia Recovery Periods,Period, Anesthesia Recovery,Periods, Anesthesia Recovery,Recovery Periods, Anesthesia
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D016037	Single-Blind Method	A method in which either the observer(s) or the subject(s) is kept ignorant of the group to which the subjects are assigned.	Single-Masked Study,Single-Blind Study,Single-Masked Method,Method, Single-Blind,Method, Single-Masked,Methods, Single-Blind,Methods, Single-Masked,Single Blind Method,Single Blind Study,Single Masked Method,Single Masked Study,Single-Blind Methods,Single-Blind Studies,Single-Masked Methods,Single-Masked Studies,Studies, Single-Blind,Studies, Single-Masked,Study, Single-Blind,Study, Single-Masked