Capnographic monitoring during anesthesia with controlled ventilation in the horse.

This research analyses the use of capnographic monitoring, a tool that measures the amount of carbon dioxide in exhaled air, during controlled-ventilation anesthesia in horses. The study determines a strong relationship between end-tidal carbon dioxide (the amount of carbon dioxide in exhaled air at the end of an exhalation) and arterial carbon dioxide, making it a satisfactory measure of changes in respiratory acid-base balance during inhalation anesthesia in horses.

Research Sample and Methodology

• The research involved a study of 45 horses that underwent halothane or isoflurane anesthesia for at least 90 minutes.
• After the first 30 minutes of anesthesia, the horses received positive pressure ventilation.
• The research focused on monitoring various parameters, including end-tidal partial pressure of carbon dioxide, arterial blood pressure, and arterial blood gases and pH.

Research Findings

• The researchers discovered a statistically significant correlation between end-tidal carbon dioxide (the amount of carbon dioxide present at the end of an exhalation) and arterial partial pressure of carbon dioxide for both types of anesthetics used, halothane and isoflurane.
• However, there was no significant correlation between end-tidal carbon dioxide and either the horse’s body weight or systolic blood pressure. This means that factors such as body weight and systolic blood pressure do not affect the amount of carbon dioxide present at the end of exhalation.
• They also found no statistically significant difference in the arterial to end-tidal carbon dioxide difference nor in alveolar dead space over anesthesia periods of up to 3 hours, regardless of the horse’s positioning. Alveolar dead space refers to the portion of the airways where gas exchange does not occur. This again suggests that the changes in these measures are not affected by time or positioning during the anesthesia.

Research Conclusion

• The results of the research led to the conclusion that monitoring end-tidal carbon dioxide is a satisfactory method of tracking changes in the respiratory acid-base balance with inhalation anesthesia in horses when ventilation is controlled. This means that capnography could be a valuable tool for clinicians when managing anesthetized horses’ ventilation.