Endotracheal saline and suction catheters: sources of lower airway contamination

BACKGROUND. Normal saline instillation prior to endotracheal suctioning is a critical care ritual that persists despite a lack of demonstrated benefit. Saline instillation may dislodge viable bacteria from a colonized endotracheal tube into the lower airway, overwhelming the defense mechanism of immunocompromised patients. OBJECTIVE. To determine the extent to which normal saline irrigation and suction catheter insertion dislodge viable bacteria from endotracheal tubes. METHODS. Endotracheal tubes from 10 critical care patients intubated for at least 48 hours were obtained immediately after extubation. Each tube was used in random order for both saline instillation and suction catheter insertion. Dislodged material was cultured for quantitative analysis. RESULTS. Suction catheter insertion dislodged up to 60,000 viable bacterial colonies. A 5-mL saline instillation dislodged up to 310,000 viable bacterial colonies. CONCLUSIONS. The potential for infection caused by dislodging bacteria into the lower airway is additional evidence that routine use of saline during suctioning procedures should be abandoned.