Hemodynamic effects of ionized calcium in horses anesthetized with halothane or isoflurane.
Abstract: To evaluate the effects of halothane and isoflurane on cardiovascular function and serum total and ionized calcium concentrations in horses, and to determine whether administration of calcium gluconate would attenuate these effects. Methods: 6 clinically normal adult Thoroughbreds. Methods: Catheters were inserted for measurement of arterial blood pressures, pulmonary arterial blood pressures, right ventricular pressure (for determination of myocardial contractility), right atrial pressure, and cardiac output and for collection of arterial blood samples. Anesthesia was then induced with xylazine hydrochloride and ketamine hydrochloride and maintained with halothane or isoflurane. An i.v. infusion of calcium gluconate was begun 75 minutes after anesthetic induction; dosage of calcium gluconate was 0.1 mg/kg of body weight/min for the first 15 minutes, 0.2 mg/kg/min for the next 15 minutes, and 0.4 mg/kg/min for an additional 15 minutes. Data were collected before, during, and after administration of calcium gluconate. Results: Halothane and isoflurane decreased myocardial contractility, cardiac index, and mean arterial pressure, but halothane caused greater depression than isoflurane. Calcium gluconate attenuated the anesthetic-induced depression in cardiac index, stroke index, and maximal rate of increase in right ventricular pressure when horses were anesthetized with isoflurane. When horses were anesthetized with halothane, a higher dosage of calcium gluconate was required to attenuate the depression in stroke index and maximal rate of increase in right ventricular pressure; cardiac index was not changed with calcium administration. Conclusions: I.v. administration of calcium gluconate may support myocardial function in horses anesthetized with isoflurane.
Publication Date: 1999-11-24 PubMed ID: 10566822
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This research investigates how two types of anesthesia, halothane and isoflurane, affect the cardiovascular function of horses, focusing on their effect on calcium levels in the blood. The study finds that administering a solution of calcium gluconate can mitigate some of the negative impacts these anesthetics have on heart function.
Research Methodology
- The study was conducted on six clinically normal adult Thoroughbred horses. The horses were fitted with catheters to measure various aspects of cardiovascular function like arterial blood pressures, pulmonary arterial blood pressures, right ventricular pressure, and cardiac output. Blood samples were also collected using these catheters.
- Anesthesia was induced using xylazine hydrochloride and ketamine hydrochloride, then maintained with either halothane or isoflurane.
- After 75 minutes of anesthetic induction, an intravenous (i.v.) infusion of calcium gluconate was started. The dosage of the calcium infusion was progressively increased over the next 45 minutes.
- The researchers collected data at several points, including before, during, and after the administration of the calcium gluconate.
Findings
- Both halothane and isoflurane reduced myocardial contractility (the ability of the heart muscle to contract), the cardiac index (a measure of cardiac function), and the mean arterial pressure. However, halothane had a stronger negative effect than isoflurane did.
- Calcium gluconate was shown to counteract the decrease in cardiac index, stroke index (a measure of how much blood the left ventricle ejects per beat), and maximal rate of increase in right ventricular pressure when the horses were anesthetized with isoflurane.
- In the case of halothane-anesthetized horses, higher dosages of calcium gluconate were needed to see similar results. Even then, it did not change the cardiac index.
Conclusion
- The results suggest that the intravenous administration of calcium gluconate can support heart function in horses that have been anesthetized with isoflurane. However, its effectiveness is reduced against the effects of halothane anesthesia.
Cite This Article
APA
Grubb TL, Benson GJ, Foreman JH, Constable PD, Thurmon JC, Olson WO, Tranquilli WJ, Davis LE.
(1999).
Hemodynamic effects of ionized calcium in horses anesthetized with halothane or isoflurane.
Am J Vet Res, 60(11), 1430-1435.
Publication
Researcher Affiliations
- Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, Champaign-Urbana 61801, USA.
MeSH Terms
- Anesthesia, Inhalation / veterinary
- Animals
- Blood Pressure / drug effects
- Calcium / blood
- Cardiac Output / drug effects
- Female
- Halothane / pharmacology
- Hemodynamics / drug effects
- Hemodynamics / physiology
- Horses / physiology
- Isoflurane / pharmacology
- Male
- Orchiectomy
- Pulmonary Artery / drug effects
- Stroke Volume / drug effects
- Time Factors
Citations
This article has been cited 1 times.- Fielding CL, Deane EL, Major DS, Mayer JR, Love JC, Peralez MS, Magdesian KG. Effects of calcium supplementation to resuscitation fluids in endurance horses: A randomized, blinded, clinical trial. J Vet Intern Med 2023 May-Jun;37(3):1216-1222.
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