Hyoscine-N-butylbromide premedication on cardiovascular variables of horses sedated with medetomidine.
Abstract: To evaluate the effects of intravenous (IV) or intramuscular (IM) hyoscine premedication on physiologic variables following IV administration of medetomidine in horses. Methods: Randomized, crossover experimental study. Methods: Eight healthy crossbred horses weighing 330 ± 39 kg and aged 7 ± 4 years. Methods: Baseline measurements of heart rate (HR), cardiac index (CI), respiratory rate, systemic vascular resistance (SVR), percentage of patients with second degree atrioventricular (2(o) AV) block, mean arterial pressure (MAP), pH, and arterial partial pressures of carbon dioxide (PaCO2 ) and oxygen (PaO2 ) were obtained 5 minutes before administration of IV hyoscine (0.14 mg kg(-1) ; group HIV), IM hyoscine (0.3 mg kg(-1) ; group HIM), or an equal volume of physiologic saline IV (group C). Five minutes later, medetomidine (7.5 μg kg(-1) ) was administered IV and measurements were recorded at various time points for 130 minutes. Results: Medetomidine induced bradycardia, 2(o) AV blocks and increased SVR immediately after administration, without significant changes in CI or MAP in C. Hyoscine administration induced tachycardia and hypertension, and decreased the percentage of 2(o) AV blocks induced by medetomidine. Peak HR and MAP were higher in HIV than HIM at 88 ± 18 beats minute(-1) and 241 ± 37 mmHg versus 65 ± 16 beats minute(-1) and 192 ± 38 mmHg, respectively. CI was increased significantly in HIV (p ≤ 0.05). Respiratory rate decreased significantly in all groups during the recording period. pH, PaCO2 and PaO2 were not significantly changed by administration of medetomidine with or without hyoscine. Conclusions: Hyoscine administered IV or IM before medetomidine in horses resulted in tachycardia and hypertension under the conditions of this study. The significance of these changes, and responses to other dose rates, requires further investigation.
© 2014 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia.
Publication Date: 2014-02-27 PubMed ID: 24576304DOI: 10.1111/vaa.12139Google Scholar: Lookup
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- Journal Article
- Randomized Controlled Trial
- Research Support
- Non-U.S. Gov't
- Animal Health
- Cardiovascular Health
- Clinical Study
- Disease Treatment
- Equine Health
- Experimental Methods
- Heart Rate
- Horses
- Hypertension
- Intramuscular Administration
- Intravenous Administration
- Medetomidine
- Pharmacology
- Physiology
- Respiratory Rate
- Sedation
- Tachycardia
- Veterinary Care
- Veterinary Medicine
- Veterinary Research
Summary
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This research study investigates the impact of hyoscine premedication on the cardiovascular system of horses that have been sedated with medetomidine. The findings reveal that hyoscine, when administered intravenously or intramuscularly prior to medetomidine, resulted in increased heart rate and blood pressure.
Objective and Methodology
- The objective of this study was to understand the effects of hyoscine premedication on physiological variables in horses sedated with medetomidine.
- A randomized crossover experimental design was used, involving eight healthy crossbred horses, each weighing around 330 ± 39 kg and aged 7 ± 4 years.
- Various parameters, including heart rate, cardiac index, respiratory rate, systemic vascular resistance, presence of second-degree atrioventricular block, mean arterial pressure, pH, and arterial partial pressures of carbon dioxide and oxygen, were assessed.
- Horses were given either intravenous hyoscine, intramuscular hyoscine, or a physiologic saline IV. Five minutes later, medetomidine was administered intravenously, with measurements recorded at various intervals for 130 minutes.
Results
- Medetomidine induced a slow heart rate, second-degree AV blocks, and increased systemic vascular resistance immediately upon administration, with no significant changes in cardiac index or mean arterial pressure.
- Hyoscine resulted in an accelerated heart rate and high blood pressure, and decreased the occurrence of medetomidine-induced second-degree AV blocks.
- Peak heart rate and mean arterial pressure were observed to be higher in IV-administered hyoscine compared to IM-administered hyoscine.
- The cardiac index significantly increased with IV-administered hyoscine, whilst the respiratory rate decreased significantly in all groups throughout the recording period.
- Neither pH levels nor arterial partial pressures of CO2 and O2 showed significant changes after the administration of medetomidine with or without hyoscine.
Conclusions
- The administration of hyoscine, either intravenously or intramuscularly, before administering medetomidine to horses resulted in tachycardia (accelerated heart rate) and hypertension (high blood pressure).
- The exact implications of these changes, as well as responses to different doses, necessitate further investigation.
Cite This Article
APA
Perotta JH, Canola PA, Lopes MC, Evora PM, Martinez PE, Escobar A, Valadão CA.
(2014).
Hyoscine-N-butylbromide premedication on cardiovascular variables of horses sedated with medetomidine.
Vet Anaesth Analg, 41(4), 357-364.
https://doi.org/10.1111/vaa.12139 Publication
Researcher Affiliations
- Department of Veterinary Clinics and Surgery, School of Agrarian Sciences and Veterinary Medicine, São Paulo State University, Jaboticabal, SP, Brazil.
MeSH Terms
- Animals
- Atrioventricular Block
- Blood Pressure / drug effects
- Butylscopolammonium Bromide / pharmacology
- Cardiac Output / drug effects
- Cross-Over Studies
- Female
- Heart Rate / drug effects
- Horses
- Hypnotics and Sedatives / administration & dosage
- Hypnotics and Sedatives / pharmacology
- Injections, Intramuscular
- Injections, Intravenous
- Male
- Medetomidine / pharmacology
- Muscarinic Antagonists / pharmacology
- Premedication
Citations
This article has been cited 1 times.- Tomsits P, Volz L, Xia R, Chivukula A, Schüttler D, Clauß S. Medetomidine/midazolam/fentanyl narcosis alters cardiac autonomic tone leading to conduction disorders and arrhythmias in mice. Lab Anim (NY) 2023 Apr;52(4):85-92.
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