Cardiovascular effects of dobutamine and phenylephrine infusion in sevoflurane-anesthetized Thoroughbred horses.
Abstract: To determine dose-dependent cardiovascular effects of dobutamine and phenylephrine during anesthesia in horses, increasing doses of dobutamine and phenylephrine were infused to 6 healthy Thoroughbred horses. Anesthesia was induced with xylazine, guaifenesin and thiopental and maintained with sevoflurane at 2.8% of end-tidal concentration in all horses. The horses were positioned in right lateral recumbency and infused 3 increasing doses of dobutamine (0.5, 1.0 and 2.0 µg/kg/min) for 15 min each dose. Following to 30 min of reversal period, 3 increasing doses of phenylephrine (0.25, 0.5 and 1.0 µg/kg/min) were infused. Cardiovascular parameters were measured before and at the end of each 15-min infusion period for each drug. Blood samples were collected every 5 min during phenylephrine infusion period. There were no significant changes in heart rate throughout the infusion period. Both dobutamine and phenylephrine reversed sevoflurane-induced hypotension. Dobutamine increased both mean arterial blood pressure (MAP) and cardiac output (CO) as the result of the increase in stroke volume, whereas phenylephrine increased MAP but decreased CO as the result of the increase in systemic vascular resistance. Plasma phenylephrine concentration increased dose-dependently, and these values at 15, 30 and 45 min were 6.2 ± 1.2, 17.0 ± 4.8 and 37.9 ± 7.3 ng/ml, respectively.
Publication Date: 2013-07-05 PubMed ID: 23832627PubMed Central: PMC3942978DOI: 10.1292/jvms.13-0104Google Scholar: Lookup
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- Journal Article
Summary
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This research article explores the cardiovascular effects of dobutamine and phenylephrine in anesthetized Thoroughbred horses. The substances were administered in increasing doses to examine their impacts on heart rate, blood pressure, cardiac output and vascular resistance.
Experimental Setup
- For this study, 6 healthy Thoroughbred horses were selected. The experiment was designed to understand the effects of the infusion of dobutamine and phenylephrine on the cardiovascular parameters of these anesthetized horses.
- Anesthesia was initiated using xylazine, guaifenesin and thiopental and maintained with sevoflurane throughout. The horses were arranged in right lateral recumbency (lying on their right side).
- Three increasing doses (0.5, 1.0 and 2.0 µg/kg/min) of dobutamine were infused for 15 minutes each. After a restoration period of 30 minutes, three increasing doses of phenylephrine (0.25, 0.5 and 1.0 µg/kg/min) were infused.
Measurement & Observation
- Cardiovascular parameters such as heart rate, arterial blood pressure, and cardiac output were measured before and at the end of each 15-minute infusion period for each drug.
- Blood samples were collected every 5 minutes during the phenylephrine infusion period to measure the plasma concentration of the drug.
- Dobutamine and phenylephrine were observed to reverse sevoflurane-induced hypotension, indicating that these drugs could counteract the drop in blood pressure caused by the anesthetic sevoflurane.
- Dobutamine increased both mean arterial blood pressure (MAP) and cardiac output (CO) due to an increase in stroke volume (amount of blood pumped by the left ventricle of the heart in one contraction).
- Phenylephrine increased MAP, but decreased CO due to an increase in systemic vascular resistance (resistance to blood flow in blood vessels).
- Plasma phenylephrine concentration increased dose-dependently at 15, 30 and 45 minutes, signifying that the drug is likely to have a cumulative effect in the bloodstream.
Conclusion
- The research affirmed that infusion of dobutamine and phenylephrine in horses during anesthesia results in significant cardiovascular effects.
- While both substances counteract sevoflurane-induced hypotension, they differ in their impacts on cardiac output and arterial blood pressure, which could influence their usage in different clinical scenarios.
Cite This Article
APA
Ohta M, Kurimoto S, Ishikawa Y, Tokushige H, Mae N, Nagata S, Mamada M.
(2013).
Cardiovascular effects of dobutamine and phenylephrine infusion in sevoflurane-anesthetized Thoroughbred horses.
J Vet Med Sci, 75(11), 1443-1448.
https://doi.org/10.1292/jvms.13-0104 Publication
Researcher Affiliations
- Racehorse Clinic, Ritto Training Center, Japan Racing Association (JRA), 1028 Misono, Ritto-shi, Shiga 520-3085, Japan.
MeSH Terms
- Anesthetics, Inhalation / administration & dosage
- Animals
- Blood Pressure / physiology
- Cardiac Output / physiology
- Cardiotonic Agents / administration & dosage
- Cardiotonic Agents / pharmacology
- Cardiovascular System / drug effects
- Dobutamine / administration & dosage
- Dobutamine / pharmacology
- Dose-Response Relationship, Drug
- Heart Rate / physiology
- Horses / surgery
- Male
- Methyl Ethers / administration & dosage
- Phenylephrine / administration & dosage
- Phenylephrine / pharmacology
- Sevoflurane
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Citations
This article has been cited 1 times.- Hopster K, Hurcombe SDA. Agreement of Bioreactance Cardiac Output Monitoring With Thermodilution in Healthy Standing Horses.. Front Vet Sci 2021;8:701339.
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