Related Experiment Video
Updated: Oct 15, 2026
Determination of Cardiac Output in a Porcine Model for Ex Vivo Pulmonary Perfusion
Published on: June 28, 2024
Cardiac output measured by lithium dilution, thermodilution, and transesophageal Doppler echocardiography in
R A Linton1, L E Young, D J Marlin
1The Rayne Institute, St Thomas' Hospital, London, UK.
Insights
Lithium dilution is an accurate and safe method for measuring cardiac output in horses during anesthesia. This technique offers a viable alternative to pulmonary artery catheterization, potentially improving anesthetic outcomes in horses.
Area of Science:
- Veterinary Medicine
- Cardiovascular Physiology
Background:
- Anesthetic mortality in horses is a significant concern.
- Accurate monitoring of cardiac output is crucial during equine anesthesia.
- Existing methods for cardiac output measurement have limitations.
Purpose of the Study:
- To evaluate the suitability of lithium dilution cardiac output (LiDCO) as a method for measuring cardiac output in anesthetized horses.
- To compare LiDCO with established methods: thermodilution cardiac output (TDCO) and transesophageal Doppler echocardiographic cardiac output (DopplerCO).
Main Methods:
- Cardiac output was measured in six anesthetized horses using LiDCO, TDCO, and DopplerCO.
- Lithium chloride was administered intravenously for LiDCO measurements.
- Cardiac output was pharmacologically manipulated to assess the methods across a range of values.
- Multiple measurements were taken for each method during four experimental periods.
Main Results:
- A strong correlation was observed between LiDCO and TDCO (r=0.94), and between DopplerCO and TDCO (r=0.94).
- LiDCO showed good agreement with TDCO (mean difference -0.86 L/min) and DopplerCO (mean difference -2.68 L/min).
- Measurements were taken over a wide range of cardiac output (10 to 43 L/min).
Conclusions:
- Lithium dilution is an accurate and suitable method for measuring cardiac output in horses.
- LiDCO offers advantages over thermodilution by avoiding pulmonary artery catheterization.
- This method is quick, safe, and may contribute to reducing anesthetic mortality in horses.
Objective:
To assess the suitability of lithium dilution as a method for measuring cardiac output in anesthetized horses, compared with thermodilution and transesophageal Doppler echocardiography.
Animals:
6 horses (3 Thoroughbreds, 3 crossbreeds).
Procedure:
Cardiac output was measured in 6 anesthetized horses as lithium dilution cardiac output (LiDCO), thermodilution cardiac output (TDCO), and transesophageal Doppler echocardiographic cardiac output (DopplerCO). For the LiDCO measurements, lithium chloride was administered i.v., and cardiac output was derived from the arterial lithium dilution curve. Sodium nitroprusside, phenylephrine hydrochloride, and dobutamine hydrochloride were used to alter cardiac output. Experiments were divided into 4 periods. During each period, 3 LiDCO measurements, 3 DopplerCO measurements, and 3 sets of 3 TDCO measurements were obtained.
Results:
70 comparisons were made between LiDCO, DopplerCO, and triplicate TDCO measurements over a range of 10 to 43 L/min. The mean (+/- SD) of the differences of LiDCO - TDCO was -0.86 +/- 2.80 L/min; LiDCO = -1.90 + 1.05 TDCO (r = 0.94). The mean of the differences of DopplerCO - TDCO was 1.82 +/- 2.67 L/min; DopplerCO = 2.36 + 0.98 TDCO (r = 0.94). The mean of the differences of LiDCO - DopplerCO was -2.68 +/- 3.01 L/min; LiDCO = -2.53 + 0.99 DopplerCO (r = 0.93).
Conclusions And Clinical Relevance:
These results indicate that lithium dilution is a suitable method for measuring cardiac output in horses. As well as being accurate, it avoids the need for pulmonary artery catheterization and is quick and safe to use. Monitoring cardiac output during anesthesia in horses may help reduce the high anesthetic mortality in this species.
Related Concept Videos
01:17Imaging Studies for Cardiovascular System I:Echocardiography
Indications: Echocardiography is utilized to diagnose heart failure, valve disorders, and myocardial infarction. It also assesses cardiac structures' size, shape, and motion, evaluates...
01:05Pulse
Pulse Rate and its Significance
Pulse rate, often measured in beats per minute (bpm), reflects the heart rate (HR), which is influenced by numerous factors such as stress, physical activity, and hormonal changes. A normal resting adult pulse rate falls between...
01:19Cardiac Output I:Effect of Heart Rate on Cardiac Output
Cardiac output (CO) refers to the total amount of blood ejected by one of the ventricles in liters per minute (L/min). In a resting adult, CO ranges from 5 to 6 L/min, adjusting according to the body's metabolic requirements.
Effect of Heart Rate on Cardiac Output
Cardiac output adapts to metabolic demands during stress, physical activity, or illness. The autonomic nervous system regulates heart rate via the sinoatrial node. The parasympathetic nervous system decreases heart rate...
01:11Cardiac Output and Stroke Volume
In an average resting adult male, the typical cardiac output averages...