Intraoperative Protective Mechanical Ventilation in Dogs: A Randomized Clinical Trial

Area of Science:

• Veterinary Anesthesiology
• Respiratory Physiology
• Comparative Medicine

Background:

• Mechanical ventilation is crucial for maintaining gas exchange during anesthesia.
• Optimizing ventilator settings, including tidal volume and positive end-expiratory pressure (PEEP), is essential for patient safety.
• Alveolar recruitment maneuvers (ARMs) are employed to improve lung aeration.

Purpose of the Study:

• To evaluate the effects of mechanical ventilation with low tidal volume (V_T) and PEEP, with or without a preceding alveolar recruitment maneuver (ARM), on gas exchange, respiratory mechanics, and hemodynamics in dogs.
• To compare the efficacy of ARM followed by PEEP versus PEEP alone in anesthetized dogs undergoing procedures.

Main Methods:

• A prospective randomized clinical trial was conducted on 21 healthy dogs undergoing periodontal treatment.
• Dogs were ventilated with a low V_T (8 mL/kg) under isoflurane anesthesia.
• Two groups were compared: one received an ARM followed by PEEP (5 cmH₂O), and the other received PEEP (5 cmH₂O) alone.
• Respiratory mechanics, gas exchange, and hemodynamic parameters were monitored.

Main Results:

• The ARM group showed a significant increase in static compliance (C_st) and oxygenation index (PaO₂/FIO₂) compared to baseline.
• The ARM also tended to reduce shunt fraction.
• No significant differences were observed in the PEEP-only group for the evaluated parameters.
• Driving pressure was significantly higher at the beginning of the evaluation before ARM.

Conclusions:

• Low tidal volume (8 mL/kg) and 5 cmH₂O PEEP without ARM provide adequate oxygenation and mechanical ventilation for up to 1 hour in dogs during dental surgery.
• The use of ARM demonstrated a slight improvement in lung compliance and oxygenation during the maneuver.