Comparison of single-breath continuous positive airway pressure manoeuvre with inhaled salbutamol to improve oxygenation in horses anaesthetized for laparotomy.

This study investigates the effectiveness of single-breath continuous positive airway pressure manoeuvre (CPAP-M) and inhaled salbutamol, as well as their combination, in improving oxygenation in horses undergoing anaesthesia for laparotomy, finding that both interventions have comparable effectiveness.

Research Design and Methodology

• The research was a clinical study involving 62 client-owned horses that were categorized as class III-V according to the American Society of Anesthesiologists status.
• Prior to anaesthesia, horses were given xylazine, midazolam, and ketamine through intravenous injections, while anaesthesia was maintained with isoflurane in oxygen under volume-controlled ventilation without positive end-expiratory pressure.
• If a horse’s partial pressure of oxygen (PaO) decreased to less than 100 mmHg (or 13.3 kPa), either CPAP-M, which involves a 50 cmHO pressure for 45 seconds, or inhaled salbutamol was administered. Success was determined if PaO reached 100 mmHg. If it remained below this threshold, the second treatment was administered.
• Different parameters were then measured and used in the study. These include the ratio of PaO to fractional concentration of oxygen in inspired air (FiO), the estimated shunt fraction (F-shunt) derived from arterial blood gas measurements, and dynamic compliance (C) calculated from the variables at the time of arterial blood analysis.

Results of the research

• The initial administration of salbutamol was given to 28 horses, and was successful in restoring optimal oxygen levels in 22 horses. CPAP-M was first delivered to 34 horses and achieved success in 26 horses. Subsequent interventions (CPAP-M after salbutamol or salbutamol after CPAP-M) were less successful.
• While both interventions improved oxygenation and C, only salbutamol led to a significant decrease in F-shunt.

Conclusion of the study

• Salbutamol and CPAP-M were found to be comparably effective in improving oxygenation and dynamic compliance in anaesthetized horses with PaO < 100 mmHg (13.3 kPa).
• The researchers suggested that further studies be conducted on a larger sample size to determine if a combination of both interventions could have more beneficial effects.