Differential artificial ventilation in anesthetized horses positioned in lateral recumbency

Area of Science:

• Veterinary Anesthesia
• Respiratory Physiology
• Comparative Medicine

Background:

• Conventional ventilation strategies can lead to suboptimal gas exchange in laterally recumbent animals.
• Optimizing ventilation in horses under anesthesia is crucial for patient outcomes.

Purpose of the Study:

• To evaluate the effects of differential ventilation on gas exchange in isoflurane-anesthetized horses.
• To compare differential ventilation with conventional ventilation, including the impact of selective positive end-expiratory pressure (PEEP).

Main Methods:

• Seven isoflurane-anesthetized horses in lateral recumbency were studied using a tracheal tube-in-tube technique for independent lung ventilation.
• Two tidal volume distribution patterns were tested, with and without selective PEEP (10 and 20 cm H2O) applied to the dependent lung.

Main Results:

• Differential ventilation significantly increased PaO2 (by 44%) and decreased shunt perfusion (by 15%) compared to conventional ventilation.
• Combining differential ventilation with selective PEEP further improved PaO2 (up to 399 mm Hg, +112%) and reduced shunt (to 15%, -33%).
• Higher PEEP levels (20 cm H2O) demonstrated more pronounced positive effects on gas exchange.

Conclusions:

• Differential ventilation is an effective strategy to improve oxygenation and reduce shunt in anesthetized horses.
• Selective PEEP applied to the dependent lung during differential ventilation offers significant additive benefits for gas exchange.
• This technique holds promise for enhancing respiratory management in equine anesthesia.