The influence of hypoxaemia, hypotension and hypercapnia (among other factors) on quality of recovery from general anaesthesia in horses.

The subject of this research is the effect of various factors like low blood oxygen (hypoxaemia), low blood pressure (hypotension), and high levels of carbon dioxide in the blood (hypercapnia) on the quality of recovery of horses from general anaesthesia. The study identifies that hypoxaemia and prolonged duration of anaesthesia negatively impact the recovery process.

Research Objectives and Methodology

• The study sponsored a single-centre, retrospective analysis of 1226 horses that had undergone anaesthesia between June 2017 and June 2021.
• Only horses and ponies above 6 months old and weighing more than 200 kg were included. Also, the subjects needed to have been anaesthetized using a xylazine or medetomidine-isoflurane balanced anaesthesia protocol and to have a comprehensive anaesthetic record.
• Data were collected from the clinic record system and the original anaesthesia records.
• Recovery periods were classified as either ‘good’ or ‘bad’ based on available recovery scores.
• A multitude of factors was considered for their potential effect on recovery scores. These factors included hypoxaemia, hypotension, and hypercapnia, as well as the anaesthesia protocol, body weight, age, breed, sex, American Society of Anesthesiologists status, type of medical procedure, emergency status, duration of anaesthesia, positioning, times spent in lateral and sternal recumbency during recovery, time until standing and nonassisted or assisted recovery.
• The research method used a generalized linear regression analysis to investigate the potential relationships. A p-value of less than 0.05 was considered statistically significant.

Key Findings

• The research found a significant correlation between hypoxaemia and a lower quality anaesthesia recovery. Meaning, horses with lower levels of oxygen in their blood during anaesthesia had worse recovery scores.
• Additionally, the duration of anaesthesia stood out as a factor that impacted the recovery scores. The longer the anaesthesia lasted, the worse the recovery tended to be.
• No other factors, including the ones tested in this research, showed a significant influence on the recovery quality.

Conclusions and Recommendations

• From its findings, the study concludes that hypoxaemia and lengthy anaesthesia duration negatively influence the quality of anaesthetic recovery in horses.
• These results underline the importance of keeping anaesthesia time as short as possible in equine medical procedures. Furthermore, they stress the need to closely monitor oxygen levels and address hypoxaemia as early as possible to ensure a better recovery.