Cardiopulmonary function during 5 hours of constant-dose isoflurane in laterally recumbent, spontaneously breathing horses.

This research paper investigates how prolonged exposure to Isoflurane, a common anesthetic for horses, affects their cardiopulmonary function. Over a five-hour duration, the authors monitored the hemodynamic and respiratory effects of this anesthetic on ten horse subjects lying on their left side.

Methodology

• Ten horses were chosen for the research and anesthetic Isoflurane was administered to them. They were laid down on their left side (laterally recumbent), while their breathing was spontaneous.
• The researchers maintained a constant concentration of 1.57% Isoflurane in oxygen for a duration of five hours.
• Various physiological parameters such as cardiac output, hematocrit, total plasma solids, PaCO2, peak inspired gas flow, and arterial blood pressure were monitored through this process. The values of these parameters at 30 minutes of Isoflurane administration served as the baseline for comparison.
• The researchers also took note of the inspiratory time (the duration of breath intake) over the course of anesthesia.
• Once the anesthetic ended, the horses’ recovery was monitored for an hour.

Findings

• The study showed that cardiovascular and respiratory factors such as cardiac output, hematocrit, total plasma solids, PaCO2, and peak inspired gas flow significantly increased over the span of five hours when compared to the baseline values.
• Arterial blood pressure increased in the first two hours of anesthesia, but then decreased to nearly baseline values for the remainder of the anesthesia duration.
• The research also found that inspiratory time decreased as the time of anesthesia increased.
• All the horses under study woke up without any issues within an hour after anesthesia was stopped.

Conclusion

• The study provides crucial insights into how a five-hour constant low dose of isoflurane impacts horses’ cardiopulmonary function. This could contribute to safer anesthetic practices for horses in veterinary medicine.