An Artificial Cough Maneuver to Remove Secretions From Below the Endotracheal Tube Cuff

Abstract

BACKGROUND: Endotracheal suctioning is mandatory to prevent complications caused by the retention of tracheal secretions. Endotracheal suctioning is often performed late, when patients show signs of respiratory and hemodynamic alterations. We conceived a prototype device that, when synchronized with the ventilator, automatically removes secretions collected below the endotracheal tube (ETT) cuff, thus avoiding endotracheal suctioning. The aim of our investigation was to assess the performance of this novel prototype in vitro. METHODS: Three studies were performed to examine the characteristics of the prototype. We tested device's ability to generate an effective artificial cough flow (artificial cough maneuver) > 1 L/s by rapidly deflating the ETT cuff within the time of a sustained inflation (at 30 and at 40 cm H 2 O) (cough flow study). We also tested the prototype's ability to remove the fluid positioned below the ETT cuff using saline dye (fluid removal study), and to prevent the aspiration of saline dye from above the ETT cuff during the deflation phase of the ETT cuff (aspiration study). The trachea model was positioned at 45°in the aspiration study, and horizontally in the other two studies. RESULTS: In the cough flow study, the prototype provided an effective artificial cough maneuver, with a mean ؎ SD of 1.78 ؎ 0.19 L/s (range, 1.42-2.14 L/s). The tracheal pressure after ETT cuff deflation never decreased below the PEEP level. In the fluid removal study, the prototype cleared the fluid from below the ETT cuff and the experimental trachea. No fluid was aspirated from the area above the ETT cuff toward the lower airways. CONCLUSIONS: We conceived an system capable of automatically expelling fluid from below the ETT cuff outside an experimental trachea by generating an artificial cough maneuver. This system may decrease the use of endotracheal suctioning and its complications. Future in vivo studies are needed to confirm this first in vitro evaluation.

Artificial Cough Maneuvers: A New Method of Secretion Clearance?

“…They found that 63-80% of synthetic sputum below the ETT was removed by 5 artificial cough maneuvers during the in vitro study, and all the radiopaque tantalum disks below the cuff were removed within 7 minutes in a swine model. 2 In another recent study, Volpe et al 11 found that the key factor to move mucus in the trachea, in an intubated model, was the difference between peak inspiratory and expiratory flows. They found that mucus clearance was ineffective if the peak inspiratory flow was higher than the peak expiratory flow.…”

“…The large pressure gradient between the airway and oral cavity generates a rapid flow, which simulates a cough to move secretions from the airways to the oral cavity. 2,10 The secretions located in the central airway, around the tip of the ETT and cuff, and below and above the cuff, are expelled by the effective artificial cough.…”

“…In addition, they found that the highest peak expiratory flow produced by the low compliance, low resistance model generated the highest clearance efficiency among the 3 models. 2 A reasonable concern regarding this maneuver is that airway pressure might decrease during the period of cuff deflation. Zanella et al 2 reported that, during cuff deflation, the average tracheal pressure decreased to a minimum of 19.1 Ϯ 3.5 cm H 2 O (12.9 -27.2 cm H 2 O).…”

“…Zanella et al 2 reported that, during cuff deflation, the average tracheal pressure decreased to a minimum of 19.1 Ϯ 3.5 cm H 2 O (12.9 -27.2 cm H 2 O). 2 This pressure may be sufficient to maintain alveolar recruitment in many patients who are intubated; however, it may be problematic in patients who require high levels of PEEP.…”

Non-Pharmacological Interventions to Prevent Ventilator-Associated Pneumonia: A Literature Review

“…An automated system based on quick cuff deflations and inflations to simulate cough was recently proposed, but its use in the clinical scenario remains to be evaluated. 101…”