Effects of Prolonged Mechanical Ventilation with a Closed Suction System on Endotracheal Tube Resistance and its Reversibility by a Closed Suction Cleaning System

The study objective was to evaluate endotracheal tubes (ETT) from extubated adult patients and compare them to new, unused, size–matched control tubes for changes in inspiratory resistance (R_insp) and peak inspiratory pressure (PIP) before and immediately after suctioning with the Airway Medix Closed Suction System (AMCSS) (Biovo Technologies, 2013 Tel Aviv, Israel). Sixteen ETTs were recovered from predominantly medical patients who had required intubation and mechanical ventilation for more than 12 hours. ETTs were evaluated within 4.5 hours of extubation. Readings were taken during square wave flow, at rates of 40 and 60 1/minute. Cleaning of extubated ETTs using the AMCSS was able to restore them to almost original conditions in terms of R_insp and PIP. The examined ETTs included tubes of various sizes ranging from internal diameter (ID) 7 to 8.5 mm and intubation periods ranging from 12 hours to 21 days. The mean Ri_nsp for the used and uncleaned ETTs was equivalent to 275% of the R_insp of sized-matched new and unused ETTs. For 8 mm ID ETTs this was comparable to a measured R_insp of a 5 mm tube. Following a single cleaning episode with the AMCSS, R_insp decreased, regaining an effective ETT ID of a 7.5 to 8 mm tube. A single suctioning episode with this device resulted in a significant reduction in R_insp, virtually restoring original flow variable values. The AMCSS represents a novel technology in closed suction systems, designed to achieve more effective inner lumen cleaning in prolonged mechanical ventilation.