Assessment of an endotracheal tube cleaning closed-suctioning system by micro-computed tomography: preliminary clinical data

Introduction

Using micro-computed tomography (MicroCT), we assessed the effectiveness of a cleaning closed-suctioning system (CSS) to remove secretions from the endotracheal tube (ETT) lumen. Biofilm growing within the ETT, soon after intubation, increases the patient's risk to develop ventilator-associated pneumonia, and new cleaning devices have been designed to keep the ETT clean from secretions [1].

Methods

In a bench test, we injected a water-based gel into unused ETTs to evaluate MicroCT scan (SkyScan 1172; Bruker, Belgium) effectiveness to measure secretions. In six critically ill patients, a cleaning CSS (Airway Medix Closed Suction system; Biovo, Tel Aviv) was used three times a day to keep the ETT clean. After extubation, we measured ETT secretions volume by MicroCT scanning over a length of 20 cm from the ETT tip. We also collected ETTs from 11 patients treated with a standard CSS as controls, and evaluated ETT microbial colonization.

Results

The volume of gel measured by MicroCT strongly correlated with the volume of injected gel (P < 0.001, R² = 0.99). At extubation, a lower amount of secretions was measured in the ETTs treated with the cleaning CSS as compared with controls (0.031 ± 0.029 vs. 0.350 ± 0.417 mm³, P = 0.028), corresponding to a smaller occupation of the cross-sectional area (average 0.3 ± 0.4 vs. 3.8 ± 4.5% respectively, P = 0.030). Microbial colonization tended to be reduced in the ETTs treated with the cleaning CSS (total bacterial charge 1.3 ± 1.7 vs. 3.6 ± 2.7 log(CFU/ml), P = 0.08).

Conclusion

MicroCT scan showed high precision and accuracy in measuring the volume of secretions in bench tests and can thus be used to evaluate the effectiveness of actions or devices studied to reduce ETT biofilm accumulation. In a small nonrandomized population of critically ill patients, the use of an ETT cleaning device appeared effective to reduce the volume of secretions present in the ETT at extubation.