Concealed air leak associated with large tidal volumes in partial liquid ventilation

Area of Science:

• Respiratory physiology
• Mechanical ventilation
• Pulmonary medicine

Background:

• Current ventilator strategies focus on lung protection by limiting pressures and volumes.
• Perfluorocarbons (PFCs) offer potential benefits in recruiting lung regions and improving mechanics.
• Optimal ventilator strategies for partial liquid ventilation (PLV) remain undefined.

Purpose of the Study:

• To compare different partial liquid ventilation (PLV) strategies in a surfactant-depleted rabbit model.
• To evaluate the safety and efficacy of varying tidal volumes (VT) and perfluorocarbon (PFC) filling levels.
• To identify optimal PLV ventilator settings to minimize barotrauma.

Main Methods:

• A surfactant-depleted rabbit model was used to test four PLV strategies.
• Strategies varied in tidal volume (9-15 ml/kg) and lung filling (partial vs. functional residual capacity [FRC]).
• Positive end-expiratory pressure (PEEP) was adjusted (5 or 9 cm H2O) based on the strategy.

Main Results:

• Oxygenation was adequate across all groups.
• Peak inspiratory pressures were not significantly different between groups.
• The strategy using large VT (15 ml/kg) with FRC-filled lungs showed a high incidence of pneumothorax and air leak.

Conclusions:

• Employing large tidal volumes with perfluorocarbon-filled lungs in PLV poses a significant risk of barotrauma.
• Alternative PLV strategies, potentially with moderate VT and partial filling, can ensure adequate gas exchange.
• Careful selection of PLV parameters is crucial for patient safety and effective ventilation.