Blood/gas partition coefficients of halothane, isoflurane and sevoflurane in horse blood.

The research examines how the gases halothane, isoflurane, and sevoflurane are absorbed into horse blood, providing measurements and concluding that the absorption rates are significantly lower than those in humans.

Research Context

• The study explores blood/gas partition coefficients (lambda(b/g)) in horse blood for three gases: halothane, isoflurane, and sevoflurane.
• These gases are volatile agents often used in anesthesia. While information is available on the lambda(b/g) for halothane in horse blood, limited data exists for isoflurane and sevoflurane.

Methods

• The research involved 24 horses that were randomly divided into three groups. Each group was allocated to a specific anesthetic agent.
• Blood samples from these horses were collected after 10 hours of fasting.
• The lambda(b/g) was calculated based on the measurement of anesthetic partial pressures in blood at a temperature of 37 degrees Celsius, a process that was executed using tonometer equilibration and headspace gas chromatography.

Results

• Findings revealed that the respective mean lambda(b/g) values for halothane, isoflurane, and sevoflurane were 1.66 (SD 0.06), 0.92 (0.04), and 0.47 (0.03).
• All these values were significantly lower than those observed in humans.
• Additionally, the study found no correlation between lambda(b/g) and weight, age, hematocrit levels, and levels of plasma triglycerides, cholesterol or total bilirubin in the horses.
• Moreover, a temperature increase by 1 degree Celsius led to a decrease in isoflurane solubility by -2.63 (0.13)%.

Conclusion

• The research concluded that the lambda(b/g) for halothane, isoflurane, and sevoflurane in fasted horses are significantly lower than those reported in humans.
• The lambda(b/g) value for halothane matched previous reports, but no positive correlation with plasma triglycerides was found.
• This knowledge can be used to improve models of anesthetic uptake, which could have implications for the use of these anesthetics in veterinary medicine.