Effects of dobutamine on cardiovascular function and respiratory gas exchange after enoximone in isoflurane-anaesthetized ponies.

This research studies the combined impacts of two drugs, enoximone and dobutamine, on the heart, blood flow, and breathing in ponies under isoflurane anesthesia. It found that, compared to enoximone alone, adding dobutamine resulted in improved cardiovascular function, oxygen delivery, and reduced dead space ventilation (unproductive breathing).

Research Context and Methods

• The study was an experimental attempt to understand the combined impact of the drugs enoximone and dobutamine on the cardiovascular system and respiratory gas exchange in ponies. This research was conducted as a prospective, randomized study.
• Six ponies, each weighing approximately 286 kg and aged about 5 years, were part of the experiment.
• The ponies were first sedated then anesthetized with isoflurane in oxygen and were maintained under this condition with assistance in ventilation.
• After anatomical stability was confirmed at 90 minutes into anaesthesia (=T0), the ponies were administered either the drug enoximone alone or enoximone followed by a constant infusion of dobutamine for a period of 120 minutes. Each pony received both treatments in a crossover trial with at least a 2-week break between treatments.
• Throughout the experiment, key parameters – heart rate, cardiac output, stroke volume, right atrial pressure, systolic, diastolic, and mean arterial pressure, blood gases, systemic vascular resistance, oxygen delivery, and several respiratory gas exchange variables were all measured to assess the effects of the administered drugs.

Research Findings

• The result showed that the combined treatment of enoximone and dobutamine significantly improved several cardiovascular parameters as compared to enoximone alone. This included an increase in heart rate, cardiac output, stroke volume, right atrial, systolic, diastolic, mean arterial pressures, packed cell volume and oxygen delivery.
• Statistically significant results were observed at different time points throughout the observational period.
• Additionally, the combined administration also resulted in an overall decrease in systemic vascular resistance and dead space ventilation (unproductive breathing where no gas exchange takes place).
• The treatment also led to increased venous oxygen saturation from 60 minutes onwards.

Conclusion

• This research suggests that the combined usage of enoximone and dobutamine have additive effects on cardiovascular parameters and also in reducing unproductive ventilation in ponies under isoflurane anaesthesia.
• These findings could have implications for medical procedures involving ponies, potentially improving their cardiovascular function and minimizing respiratory issues during anaesthesia.