Continuous intratracheal gas suctioning combined with ventilator leak-compensation may enhance carbon dioxide removal...

Although tracheal gas insufflation (TGI) and aspiration of expiratory gas in the dead space (ASPIDS) have been shown to enhance CO₂ removal by washing out the anatomical dead space, clinical implementation has been limited due to complications including unintended airway pressure increases and mucosal damage, as well as their complexity. We developed a novel respiratory management system combining continuous intratracheal gas suctioning with pressure control ventilation, utilizing the leak compensation function of modern ventilators. The aim of this study was to document the preliminary physiological observations of this system in a proof-of-concept porcine model.

Two female pigs weighing approximately 30 kg were intubated with 7.5 mm cuffed endotracheal tubes and paralyzed under general anesthesia. Each pig was studied under four different ventilatory conditions: two with healthy lungs and two with experimentally induced lung injury (created by repeated whole-lung lavage with normal saline and injurious ventilation until PaO₂/F_IO₂ < 300 mmHg). A 10 Fr closed suction catheter was inserted into the trachea. Using the leak compensation function of a Puritan Bennett™ 840 ventilator, heated and humidified gas was automatically supplied at the same flow rate as the continuous suctioning flow (13-14 L/min), maintaining constant circuit pressure. Pressure-controlled ventilation was applied, and arterial blood gas was analyzed before, during, and after continuous suctioning. PEEP was increased by 1 cmH₂O during suctioning to compensate for pressure loss through the endotracheal tube.

A total of eight experimental runs were performed (two pigs × four conditions each: two healthy, two injured lung conditions). Baseline PaCO₂ ranged from 42.2 to 71.8 mmHg. During suctioning, PaCO₂ decreased in seven conditions (reductions: 0.9 to 10.1 mmHg; 1.8% to 14.1%) and increased in one condition (3.0 mmHg; 5.9%). The largest reductions occurred in conditions with higher baseline PaCO₂. After cessation of suctioning, PaCO₂ returned toward baseline levels. No ventilator alarms or operational problems occurred during the experiments.

In a proof-of-concept study using a porcine model with both healthy and injured lungs, continuous intratracheal gas suctioning combined with ventilator leak-compensation may enhance CO₂ removal efficiency without increasing driving pressure. This technique has potential as a simple adjunct to conventional mechanical ventilation for enhancing CO₂ removal in patients with respiratory failure, while further investigation is required for safety and clinical applicability.