Cardiorespiratory, endocrine and metabolic changes in ponies undergoing intravenous or inhalation anaesthesia.

The study investigates the differences in cardiorespiratory, hormonal, and metabolic responses in ponies anaesthetized either by inhalation or intravenous methods. It concludes that total intravenous anaesthesia (TIVA) resulted in better cardiorespiratory performance and lesser endocrine stress compared to halothane inhalation anaesthesia.

Study Design and Procedure

• The experiment involved six Welsh gelding ponies. They were given premedications and anesthetized either through the injection of a combination of substances or by inhalation of halothane in oxygen.
• The same ponies were anesthetized one month later, but this time using total intravenous anaesthesia (TIVA) while they breathed oxygen-rich air.

Data Collection

• During these two processes, various physical and internal metrics were tracked and examined. These included factors like heart rate, arterial blood pressure, respiratory rate, blood gases, temperature, glucose and cortisol levels, etc.
• The effects of halothane anesthesia were specifically explored with respect to the assessment of beta-endorphin, met-enkephalin, dynorphin, arginine vasopressin (AVP), and catecholamines. In contrast, 11-deoxycortisol was measured during TIVA only.

Findings and Conclusions

• It was found that the inhalation of halothane led to more considerable cardiorespiratory depression compared to TIVA.
• Increased levels of glucose (hyperglycaemia) were seen in both groups. However, lactate and AVP increased only during halothane anaesthesia. Cortisol, a stress hormone, increased during halothane anaesthesia but decreased during TIVA.
• There were no significant changes in the other hormones during anaesthesia. Recovery in both cases was smooth, indicating both methods to be viable.
• This study concludes that TIVA was more effective by providing superior cardiorespiratory performance and reducing the endocrine stress response seen during halothane anesthesia.