Cardiopulmonary effects of continuous intravenous infusion of guaifenesin, ketamine, and xylazine in ponies.

This research study explores the cardiopulmonary effects of a continuous intravenous solution of guaifenesin, ketamine, and xylazine in anesthetized ponies. It found that systolic, diastolic, and mean arterial pressures and the left ventricular stroke work index showed significant decreases after injection but heart rate and other parameters remained relatively stable throughout the study.

Method

• Eight ponies were included in this study and were anesthetized with a solution containing guaifenesin, ketamine, and xylazine, suspended in 5% dextrose water.
• The anesthesia was induced by an intravenous (IV) injection at a dose of 1.1ml per kg of the pony’s weight, following which a continuous IV infusion was administered at a rate of 2.75 ml per kg per hour.

Results

• Hemodynamic measurements showed no significant change in heart rate, rate-pressure product, mean pulmonary artery pressure, and standard bicarbonate throughout the study.
• Measurements of systolic, diastolic, and mean arterial pressures, and left ventricular stroke work index showed significant decreases at 5 and 15 minutes after injection.
• Systolic blood pressure began to return to baseline levels at around 30 minutes post-injection, but diastolic and mean arterial pressures remained significantly lower for the duration of the study.
• The cardiac index and arterial pH showed decreases but only at the 5-minute mark.
• Systemic vascular resistance notably decreased 60 minutes after the bolus injection.
• Signs of hypoventilation, evident by increased levels of PaCO2, were observed 5 minutes after the injection was administered.

Conclusion

• This study suggests that usage of a continuous IV infusion of the mentioned combined anesthetic in ponies leads to significant drops in various arterial pressures and left ventricular stroke work index shortly after administration, though some parameters, like systolic blood pressure, seem to return to normal levels after 30 minutes.
• However, it is also associated with hypoventilation, suggested by increased levels of PaCO2 shortly after administration.
• While the heart rate and some other measurements remained relatively stable, certain significant physiological changes observed require careful monitoring and consideration when administering this anesthetic blend.