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Cardiac output technologies with special reference to the horse
Kevin T T Corley1, Lydia L Donaldson, Mary M Durando
1Equine Referral Hospital, Royal Veterinary College, Hertfordshire, UK. kcorley@rvc.ac.uk
Journal of Veterinary Internal Medicine
|May 31, 2003
Summary
Accurately measuring cardiac output (CO) is vital for horses with critical illness or cardiovascular disease. Lithium dilution is currently the most suitable method for equine clinical use, offering a balance of accuracy and practicality.
Area of Science:
- Veterinary Medicine
- Cardiovascular Physiology
- Equine Health
Background:
- Hemodynamic alterations are common in critically ill horses, those undergoing anesthesia, with cardiovascular disease, or during exercise.
- Accurate measurement of cardiac output (CO) is essential for understanding and managing these hemodynamic changes in both clinical and research settings.
- Several new CO measurement techniques have emerged, with some now validated and used in horses.
Purpose of the Study:
- To review and compare various methods for measuring cardiac output (CO) in horses.
- To identify the most clinically practical and accurate method for CO measurement in equine practice.
Main Methods:
- Review of established and emerging techniques for CO measurement in horses, including Fick method, indicator dilution (indocyanine green, thermodilution, lithium), Doppler echocardiography, bioimpedance, and pulse contour analysis.
- Discussion of the technical demands, invasiveness, and validation status of each method in equine populations.
- Focus on methods suitable for clinical application in horses.
Main Results:
- The Fick method, while historically used, is technically demanding for clinical application.
- Indicator dilution techniques have limitations: indocyanine green is cumbersome, thermodilution requires invasive right heart catheterization, and lithium dilution requires peripheral catheterization but has been validated in adult and neonatal horses.
- Doppler echocardiography is noninvasive but requires significant technical expertise; bioimpedance and pulse contour analysis are not yet validated in horses.
Conclusions:
- Lithium dilution offers a validated and practical approach for measuring cardiac output in clinical equine settings.
- While other methods exist, their technical demands or invasiveness limit their routine use in horses.
- Continued research into noninvasive techniques like Doppler echocardiography is warranted, but lithium dilution is the current best option for equine CO measurement.