Cardiopulmonary effects of prostacyclin infusion in anesthetized horses.

This study investigated how administering intravenous prostacyclin impacts the cardiopulmonary system of anesthetized horses. The researchers observed that at high doses, prostacyclin caused significant alterations to arterial pressure, vascular resistance, heart rate, cardiac output and oxygen content in blood.

Methodology

• The study focused on six horses that were anesthetized using halothane.
• Prostacyclin was given to these horses intravenously at three different dosages.
• These dosage levels were at 10, 30, and 100 nanograms per kilogram of the horse’s body weight per minute.
• The researchers took various measurements including facial and pulmonary artery pressures, heart rate, cardiac output, blood temperature, and the pH, PCO2, and PO2 levels of arterial and mixed venous blood.
• Arterial blood was collected to determine glucose, lactate, and packed cell volume (PCV).
• Mixed venous blood samples were furthermore analyzed for 6-keto-prostaglandin F1 alpha and catecholamines.

Findings and Conclusions

• An infusion of prostacyclin at 10 ng/kg/min didn’t cause any changes in the measurements.
• At the dosage of 30 ng/kg/min, significant drops in diastolic, mean arterial pressure and in arterial oxygen partial pressure were observed at 15-, and 30-minute intervals.
• A rate of 100 ng/kg/min caused clearly noticeable changes. This includes significant drops in arterial pressure, total vascular resistance, total pulmonary resistance.
• Simultaneously, the heart rate increased slightly, but a major increase of up to 44% was seen in cardiac output. Also, arterial oxygen tension reduced drastically from 311 to 137 and 135 mm of Hg at 15- and 30-minute readings respectively.
• There was an increase observed in blood glucose levels while prostacyclin infusions of 30 and 100 ng/kg/min increased blood concentrations of 6-keto-prostaglandin F1 alpha by factors of 5 and 40, respectively.
• No significant changes were observed in catecholamine concentrations.

In conclusion, the data that was collected points towards the fact that high doses of IV prostacyclin can cause impactful changes in the cardiopulmonary system of anesthetized horses. This outcome helps to better understand the effects of prostacyclin in horses under anesthesia, which could be valuable for veterinary medicine.