Effects of single hyperinflation using a sustained high pressure manoeuvre during inhalation anaesthesia in horses.

This study investigates the impact of a single hyperinflation procedure using a sustained high-pressure manoeuvre during inhalation anaesthesia on horses. It finds that although the technique can briefly improve arterial oxygenation in horses breathing spontaneously while in a dorsal recumbent position, it has limited effectiveness overall.

Objective and Method of the Study

• The study aims to explore the effects of a single hyperinflation technique using a sustained high-pressure manoeuvre (SHPM) on horses under inhalation anaesthesia. These effects are measured primarily in terms of changes in cardiorespiratory parameters and arterial oxygenation.
• To carry out this investigation, the researchers recruited 28 male horses owned by clients. Half of these horses were in a dorsal recumbent (on their back) position, while the other half were laterally recumbent (on their side).
• Within each of these groups, horses were randomly allocated to either breathe spontaneously or receive mechanical ventilation.

The Procedure and Data Collection

• After a 30-minute period of anaesthesia, baseline cardiorespiratory parameters were collected for each horse. Then a SHPM of 50 cmH2O for 50 seconds was performed.
• The team monitored these cardiorespiratory parameters and the arterial oxygenation levels before and after the SHPM, allowing them to assess the impact of the manoeuvre.

Findings of the Study

• The research found that in the group of horses that were breathing spontaneously and were in a dorsal recumbent position, a venous admixture (a mixing of venous and arterial blood) developed more significantly than in other groups.
• For these horses, a single SHPM led to only a partial and transient improvement in arterial oxygenation. This suggests that the technique, while producing some temporary benefits, is not wholly effective in this context.
• For the other groups of horses — those in lateral recumbency and those under mechanical ventilation — the study found no notable benefits from applying the SHPM.

The findings of this research imply that a single SHPM may have some short-term benefits for spontaneously breathing, dorsally recumbent horses under inhalation anaesthesia. However, its overall effectiveness appears limited, indicating that further research is required to find more efficient methods to improve arterial oxygenation and other cardiorespiratory parameters in anaesthesia procedures involving horses.