Haemodynamic effects of a sixty minute infusion of dopamine hydrochloride in horses anaesthetised with halothane.
Abstract: To describe the haemodynamic effects of a 60 min infusion of dopamine 4 microg/kg bwt/min during halothane anaesthesia, 7 mature Thoroughbred horses were studied. The infusion began 1 h after induction of anaesthesia by romifidine (100 microg/kg) and ketamine (2.2 mg/kg bwt). Throughout the period of dopamine infusion and for 30 min after its discontinuation, the horses were ventilated by intermittent positive pressure to maintain PaCO2 between 4.6-5.4 KPa. Inspired halothane concentration was adjusted to maintain an end tidal halothane concentration of 0.9%. Haemodynamic variables were measured using intracardiac strain gauge transducers sited in the left and right ventricle, aorta, and pulmonary artery. Left ventricular pressure was differentiated to obtain maximal rate of increase of intraventricular pressure (LVdp/dtmax). Transoesophageal Doppler echocardiography was performed to measure maximum aortic blood flow velocity (vmax) and acceleration (dv/dtmax), left ventricular velocity time integral (vTI) and cardiac output (CO), and left ventricular pre-ejection period (PEP) and ejection time (ET). Measurements were made during the 60 min infusion, and for 30 min after the infusion was discontinued. Infusion of dopamine 4 microg/kg/min significantly decreased mean aortic pressure, while left and right ventricular end-diastolic pressure and mean pulmonary artery pressure remained unchanged. There was a small, but significant, increase in heart rate during dopamine infusion. Maximum acceleration of aortic blood flow, CO and vTI were also significantly increased by dopamine infusion. Maximal rate of increase of intraventricular pressure (LVdp/dtmax) was significantly decreased 10 min after commencing infusion, but then returned to baseline for the remainder of the study. Left ventricular pre-ejection period (PEP) decreased during dopamine infusion whilst ejection time (ET) significantly increased. All measured variables except LVET had returned to baseline values within 30 min of discontinuing the infusion. This study demonstrated beneficial effects of dopamine infusion upon left ventricular systolic function. However, the therapeutic value of the drug is likely to be limited in clinical anaesthesia due to the simultaneous falls in arterial blood pressure which accompany its administration.
Publication Date: 1998-08-15 PubMed ID: 9705114DOI: 10.1111/j.2042-3306.1998.tb04103.xGoogle Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The study investigates the impact of a 60-minute dopamine infusion during halothane anaesthesia on the cardiovascular system of anaesthetized thoroughbred horses. The researchers found that the infusion had positive effects on left ventricular systolic function but its clinical utility could be limited due to accompanying drops in arterial blood pressure.
Study Design and Procedure
- Seven mature thoroughbred horses were used for the study. The horses were first anesthetized with romifidine and ketamine and then infused with dopamine hydrochloride for an hour. This infusion started an hour after the induction of the anaesthesia.
- Dopamine infusion was delivered at a rate of 4 micrograms per kilogram body weight per minute.
- A continuous positive airway pressure was maintained to secure the partial pressure of carbon dioxide between 4.6 and 5.4 KPa.
- Halothane concentration was tweaked to yield an end tidal concentration of 0.9%.
Measurement of Haemodynamic Variables
- Various heart and blood pressure metrics were measured using transducers (devices that convert pressure variations to electric signals) strategically placed in the right and left ventricles, aorta, and pulmonary artery.
- Computations allowed for obtaining maximum rate of increase of intraventricular pressure referred to as LVdp/dtmax.
- Transoesophageal Doppler echocardiography, a form of ultrasound test that visualizes the heart, was done to get max aortic blood flow velocity, its acceleration, velocity time integral (the area under the velocity-time curve), cardiac output, and measurements related to left ventricle performance – pre-ejection period and ejection time.
Findings
- Dopamine infusion resulted in a notable reduction in mean aortic pressure, while the mean pressures of the right and left ventricular end-diastolic and pulmonary artery remained stable.
- Heart rate experienced a small but significant increase with dopamine infusion.
- Metrics related to aortic flow such as CO, vTI, and maximum acceleration showed significant improvement with dopamine.
- LVdp/dtmax initially decreased 10 minutes into the infusion but then reverted to the baseline for the remaining study duration.
- The left ventricular pre-ejection period decreased with dopamine infusion while the ejection time increased significantly.
- Almost all variables reverted to their baseline values within half an hour of stopping the infusion. The only exception was the left ventricular ejection time.
Conclusion
- The study findings demonstrated the beneficial effects of dopamine infusion on the left ventricular systolic function. However, the therapy’s utility in clinical anaesthesia settings might be limited since it also led to a drop in the arterial blood pressure.
Cite This Article
APA
Young LE, Blissitt KJ, Clutton RE, Molony V.
(1998).
Haemodynamic effects of a sixty minute infusion of dopamine hydrochloride in horses anaesthetised with halothane.
Equine Vet J, 30(4), 310-316.
https://doi.org/10.1111/j.2042-3306.1998.tb04103.x Publication
Researcher Affiliations
- Department of Veterinary Clinical Studies, Royal (Dick) School of Veterinary Studies, Near Roslin, Midlothian, UK.
MeSH Terms
- Anesthesia, Inhalation / veterinary
- Anesthetics, Inhalation
- Animals
- Cardiac Catheterization / veterinary
- Dopamine / administration & dosage
- Dopamine / pharmacology
- Echocardiography, Transesophageal / veterinary
- Female
- Halothane
- Hemodynamics / drug effects
- Horses / physiology
- Infusions, Intravenous / veterinary
- Male
Citations
This article has been cited 1 times.- Cattai A, Rabozzi R, Ferasin H, Isola M, Franci P. Haemodynamic changes during propofol induction in dogs: new findings and approach of monitoring. BMC Vet Res 2018 Sep 12;14(1):282.
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