The effects of halothane and isoflurane on cardiovascular function in dorsally recumbent horses undergoing surgery.
Abstract: To determine the haemodynamic effects of halothane and isoflurane with spontaneous and controlled ventilation in dorsally recumbent horses undergoing elective surgery. Methods: Prospective randomized clinical trial. Methods: Twenty-five adult horses, body mass 487 kg (range: 267-690). Methods: Horses undergoing elective surgery in dorsal recumbency were randomly assigned to one of four treatment groups, isoflurane (I) or halothane (H) anaesthesia, each with spontaneous (SB) or controlled ventilation (IPPV). Indices of cardiac function and femoral arterial blood flow (ABF) and resistance were measured using transoesophageal and transcutaneous Doppler echocardiography, respectively. Arterial blood pressure was measured directly. Results: Four horses assigned to receive isoflurane and spontaneous ventilation (SBI) required IPPV, leaving only three groups for analysis: SBH, IPPVH and IPPVI. Two horses were excluded from the halothane groups because dobutamine was infused to maintain arterial blood pressure. Cardiac index (CI) was significantly greater, and pre-ejection period (PEP) shorter, during isoflurane compared with halothane anaesthesia with both spontaneous (p = 0.04, p = 0.0006, respectively) or controlled ventilation (p = 0.04, p = 0.008, respectively). There was an association between CI and PaCO(2) (p = 0.04) such that CI increased by 0.45 L minute(-1)m(-2) for every kPa increase in PaCO(2). Femoral ABF was only significantly higher during isoflurane compared with halothane anaesthesia during IPPV (p = 0.0006). There was a significant temporal decrease in CI, but not femoral arterial flow. Conclusions: The previously reported superior cardiovascular function during isoflurane compared with halothane anaesthesia was maintained in horses undergoing surgery. However, in these clinical subjects, a progressive decrease in CI, which was independent of ventilatory mode, was observed with both anaesthetic agents. Conclusions: Cardiovascular function may deteriorate progressively in horses anaesthetized for brief (<2 hours) surgical procedures in dorsal recumbency. Although cardiovascular function is superior with isoflurane in dorsally recumbent horses, the need for IPPV may be greater.
Publication Date: 2008-02-18 PubMed ID: 18282256DOI: 10.1111/j.1467-2995.2007.00376.xGoogle Scholar: Lookup
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- Journal Article
- Randomized Controlled Trial
- Research Support
- Non-U.S. Gov't
Summary
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This study investigates the impact of halothane and isoflurane on cardiovascular function in horses positioned dorsally (on their back) for surgery. The research concluded that isoflurane maintains superior heart function compared to halothane in these horses, although cardiac function was found to decrease progressively over time with both anesthetics.
Research Methodology
- The study was a prospective randomized clinical trial, which means the experiment was planned before it started and the horses were randomly assigned to one of the treatment groups.
- 25 adult horses with an average weight of 487kg were used in the experiment. The horses were chosen for elective surgery (surgery that is scheduled in advance).
- The horses were divided into four treatment groups – anaesthesia with isoflurane or halothane, each either spontaneous or controlled ventilation. Spontaneous breathing means the horses breathed on their own, whereas controlled ventilation implies a machine helped with the breathing.
- The cardiac function was monitored using transoesophageal and transcutaneous Doppler echocardiography, while arterial blood flow and resistance were measured through the femoral artery.
Results and Conclusion
- Four of the horses that were supposed to breathe spontaneously under isoflurane required controlled ventilation, meaning they were moved to a different group. This left three groups for analysis. Two horses were also removed from the halothane groups because dobutamine was used to keep their blood pressure stable.
- In both spontaneous and controlled ventilation groups, the cardiac index (which is a measure of heart function) was significantly higher, and the pre-ejection period (time before the heart pushes the blood out) was significantly lower with isoflurane compared to halothane. This suggests that isoflurane is more efficient at maintaining heart function than halothane, regardless of the ventilation mode.
- There was also a correlation between the cardiac index and PaCO2 such that the cardiac index increased by 0.45 L minute(-1)m(-2) for every kPa increase in PaCO2. This suggests that increasing carbon dioxide levels in the blood may improve heart function.
- Only under controlled ventilation was femoral arterial blood flow significantly higher with isoflurane compared to halothane.
- Regardless of the anesthetic used, the cardiac index decreased over time. This means that the heart function of the horses worsened progressively during the anaesthesia. Additionally, this decrease was observed regardless of the ventilation mode (spontaneous or controlled).
- In conclusion, even though isoflurane supported better cardiovascular function in horses during surgery, there was an observed progressive decline in cardiac function with both anaesthetics. Furthermore, this study suggests that there might be a higher need for controlled ventilation (IPPV) with the use of isoflurane.
Cite This Article
APA
Blissitt KJ, Raisis AL, Adams VJ, Rogers KH, Henley WE, Young LE.
(2008).
The effects of halothane and isoflurane on cardiovascular function in dorsally recumbent horses undergoing surgery.
Vet Anaesth Analg, 35(3), 208-219.
https://doi.org/10.1111/j.1467-2995.2007.00376.x Publication
Researcher Affiliations
- Department of Veterinary Clinical Studies, Royal (Dick) School of Veterinary Studies, Easter Bush Veterinary Centre, Near Roslin, Midlothian, UK. karen.blissitt@ed.ac.uk
MeSH Terms
- Anesthesia, Inhalation / veterinary
- Anesthetics, Inhalation / pharmacology
- Animals
- Blood Flow Velocity / drug effects
- Blood Pressure / drug effects
- Female
- Halothane / pharmacology
- Heart Rate / drug effects
- Horses
- Isoflurane / pharmacology
- Male
- Respiration / drug effects
- Time Factors
Citations
This article has been cited 1 times.- Cerullo M, Driessen B, Douglas H, Hopster K. Changes in Arterial Blood Pressure and Oxygen Tension as a Result of Hoisting in Isoflurane Anesthetized Healthy Adult Horses.. Front Vet Sci 2020;7:601326.
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