Arterial-alveolar carbon dioxide tension difference and alveolar dead space in halothane anaesthetised horses.

This research studied the relationship between arterial-alveolar carbon dioxide tension differences and alveolar dead space during clinical halothane anaesthesia in 110 horses.

Objective and Methods

• The objective of the study was to measure and establish the arterial-alveolar carbon dioxide tension differences (a-A) PCO2 and alveolar dead space during halothane anaesthesia of horses. These measurements were performed using continuous infra-red carbon dioxide analysis of expiratory gas.
• 110 horses underwent clinical halothane anaesthesia for the above research.

Results

• Average arterial-alveolar carbon dioxide tension differences were found to be 1.6 +/- 0.8 kPa.
• When expressed as a percentage of alveolar tidal volume, the average alveolar dead space was 23 +/- 13 per cent.

Examined Variables and their Influence

• The researchers tested the effects of age, weight, body position, mode of respiration, and duration of anaesthesia on (a-A) PCO2 and alveolar dead space.
• Results indicated that weight significantly increased both (a-A) PCO2 and alveolar dead space with a P-value of less than 0.0001, suggesting a strong level of statistical significance.
• The adoption of dorsal recumbency (i.e., lying on the back) also had a positive influence on both (a-A) PCO2 and alveolar dead space, with a P-value of less than 0.01, indicating statistical significance.
• Intermittent positive pressure ventilation was found to positively influence alveolar dead space (P-value less than 0.0001), suggesting its significant contribution to an increased alveolar dead space.
• The duration of anaesthesia also positively affected the alveolar dead space (P less than 0.05), indicating its significant connection with the increase of dead space in alveoli during anaesthesia.