Determination of cardiac output in neonatal foals by ultrasound velocity dilution and its comparison to the lithium dilution method.

The research article discusses a study comparing cardiac output (CO) measurement techniques, ultrasound velocity dilution (UDCO), and lithium dilution (LiDCO) in neonatal foals. The study found that both methods were effectively applicable, with a high degree of correlation between the two, suggesting UDCO can also be used reliably for measuring CO in neonatal foals under anesthesia.

Objective of the Study

• The primary goal of the study was to compare two techniques used for measuring cardiac output (CO), namely lithium dilution (LiDCO) and ultrasound velocity dilution (UDCO).
• The study aimed to validate the effectiveness of UDCO in different cardiovascular states (high, intermediate, and low CO) of anesthetized neonatal foals, comparing it with the standard LiDCO technique.

Methodology

• The researchers carried out a prospective study at a university teaching hospital, involving six neonatal foals aged between 1 to 3 days and weighing between 38 to 45 kg.
• The foals were anesthetized and scientifically equipped to measure heart rate, arterial blood gases, direct blood pressure, and CO.
• CO measurements were taken at baseline and during low, intermediate, and high CO states, using both LiDCO and UDCO methods.
• The CO measurements were then converted to cardiac index (CO/body weight) values for statistical analysis.

Results

• CO measurements taken by LiDCO ranged from 4.0 to 14.0 L/min, resulting in a cardiac index ranging from 75.5 and 310 mL/kg/min.
• The study found no significant effect of blood pressure variation on the bias or relative bias.
• The mean bias and relative bias of UDCO compared with LiDCO were -20.1±39.2 mL/kg/min and -7.7±23.4%, respectively.
• The concordance correlation coefficient between LiDCO and UDCO was 0.833, indicating a strong agreement between the two methods.

Conclusions

• The study concluded that the UDCO method has acceptable clinical utility for measuring CO in healthy anesthetized newborn foals when compared with the LiDCO.
• The findings suggest that there is a significant correlation between the two methods, validating the UDCO’s applicability in neonatal foals.