Evaluation of Endotracheal Tube Scraping on Airway Resistance

Abstract

Background: Spontaneous breathing trials (SBTs) are used to assess the readiness for discontinuation of mechanical ventilation. When airway resistance (R_aw) is elevated, the imposed work of breathing can lead to prolongation of mechanical ventilation. Biofilm and mucus build-up within the endotracheal tube (ETT) can increase R_aw. Scraping the ETT can remove the biofilm build-up and decrease mechanical R_aw. The primary aim of this study was to evaluate the impact of ETT scraping on R_aw. The secondary aim was to determine whether decreasing R_aw would impact subsequent SBT success.

Methods: Intubated, mechanically ventilated subjects were enrolled if they failed an SBT and had an R_aw of > 10 cm H₂O/L/s. SBT failure was based on institutional guidelines, and R_aw was calculated by subtracting the difference between the measured peak and plateau pressures using a square flow waveform with an inspiratory flow set at 60 L/min. The endOclear device was inserted into the ETT and withdrawn per manufacturer's guidelines. Scraping was repeated until the ETT was cleared. Change in R_aw was compared pre- and post-ETT scraping using a paired t test. A Mann-Whitney U test evaluated the difference in percentage change in R_aw between SBT groups.

Results: Twenty-nine subjects completed the study. The mean pre- and post-ETT scraping R_aw values were 15.17 ± 3.83 and 12.05 ± 3.19 cm H₂O/L/s, respectively (P < .001). Subsequent SBT success was 48%; however, there was no difference in percentage change in R_aw between subsequent passed SBT (18.61% [interquartile range 8.90-33.93%]) and failed SBT (23.88% [interquartile range 0.00-34.80%]), U = 78.5, z = -0.284, P = .78. No adverse events were noted with ETT scraping.

Conclusions: This study demonstrated that ETT scraping can reduce R_aw. The decrease in R_aw post-ETT scraping did not affect subsequent SBT success.

Keywords: airway obstruction; biofilm; endotracheal extubation; endotracheal tube; endotracheal tube obstruction; mechanical ventilation; resistance; secretion removal; spontaneous breathing trial; work of breathing.