Evaluation of a New Device for Clearing Secretions From Lower Airways

Abstract

Background:

Endotracheal intubation promotes the retention of secretions in the lower airways, potentially leading to infections and obstructions. A novel endotracheal cuff controller, synchronized with the ventilator, is designed to remove secretions from both above and below the endotracheal tube (ETT) cuff by generating a semi-automatic “artificial cough” through brief ETT cuff deflation during the inspiratory phase of a ventilator breath. This study assessed, first, in vitro, the accuracy of a computation for estimating the cough flow and, subsequently, in subjects, the device’s effectiveness in moving secretions from lower airways toward the mouth during invasive ventilation.

Methods:

In the in vitro study, the mean cough flow estimated by the ratio between the expiratory volume lost and the duration of the cuff deflation was compared with the actual cough flow measured using flow meters. In the clinical study, we enrolled subjects admitted to the ICU. Three artificial cough maneuvers were performed within 3 min during a sigh (inspiratory pressure of 35 cm H₂O for ∼1.8 s). Aspiration of the oral cavity was conducted before the first maneuver and after the third maneuver.

Results:

A strong linear association was found between actual and computed cough flow (Pearson’s correlation coefficient 0.991, 95% CI: 0.987–0.994). Twenty-eight subjects were enrolled. After device activation, oral secretions were detected in 78.6% of subjects (responders). Cough flow was similar in both responders and nonresponders, with a mean highest value of 23.3 ± 11.5 L/min. Demographic, physiological, and ventilatory parameters before and after the maneuvers were also similar. No relevant adverse events were recorded, except for one transient episode of hypotension.

Conclusions:

The cough flow can be accurately estimated from the expiratory volume lost. The device successfully generated effective cough flows in all subjects, clearing secretions from the trachea to the mouth in nearly 80% of cases.