A volume-controlled liquid ventilator with pressure-limit mode: imperative expiratory control

Area of Science:

• Biomedical Engineering
• Respiratory Physiology
• Critical Care Medicine

Background:

• Liquid ventilation with perfluorocarbon (PFC) offers potential benefits for patients with respiratory distress syndrome.
• Conventional gas ventilation may have limitations in severe respiratory failure.

Purpose of the Study:

• To develop and evaluate a novel volume-controlled liquid ventilator with pressure-limit control for respiratory support.
• To assess the efficacy of PFC liquid ventilation in achieving adequate oxygenation and carbon dioxide removal in an animal model.

Main Methods:

• A volume-controlled liquid ventilator with a pressure-limit mode was developed, utilizing mechanical inspiration and gravity-assisted expiration.
• Perfluorocarbon (PFC) oxygenation and CO2 removal were managed via a membrane oxygenator.
• The system was tested in 5 rabbits, with intratracheal pressure (Paw) monitored and controlled within set limits.

Main Results:

• The liquid ventilator achieved excellent arterial blood gas levels, with average pH of 7.45, Pao2 of 369 mm Hg, Paco2 of 46.2 mm Hg, and Sao2 of 100%.
• The pressure-limit control system functioned effectively.
• Fluorothorax (PFC leakage into the thoracic cavity) occurred in 3 animals when the upper pressure limit was increased, suggesting a need for improved expiratory control.

Conclusions:

• The developed liquid ventilator demonstrates effective gas exchange capabilities in an animal model.
• The occurrence of fluorothorax highlights the critical need for an optimized expiratory control mechanism in liquid ventilation systems.
• Further refinement of the expiratory phase is essential for the clinical advancement of this liquid ventilation technology.