An in vitro evaluation of the effectiveness of endotracheal suction catheters

Tracheal suction catheters (TSCs) are used to clear mucus from an endotracheal tube (ETT). The clearance rate is critical because airway mucus stasis leads to obstruction, but prolonged catheter suctioning can lead to hypoxemia. The rate of mucus clearance from an ETT is thought to be influenced by the properties of the mucus, the pressure used to suction the mucus, and the diameter of the catheter. In this study, different adult TSCs were evaluated for their ability to suction mucus simulants that had properties similar to airway mucus.

Six different 14F TSC designs were evaluated. All catheters had the same end hole size, but the two side holes were sized at 3 mm, 4 mm, or 5 mm. A coagulant (Polyox Water Soluble Resin Coagulant NF; Dow Chemical Company; Cary, NC) was mixed with water at concentrations of 0.5%, 1.5%, and 3.0% to simulate mucus or sputum. Suction effectiveness was evaluated by the mass percentage of the coagulant suctioned over 10 s at 100 mm Hg from an 8.0 ETT.

The 1.5% and 3.0% simulants had properties comparable to human airway mucus and sputum. Suction effectiveness was less with the 3.0% coagulant simulant compared with the 1.5% and 0.5% simulants. Suction effectiveness was greater (p < 0.01) with TSCs that had nonparallel holes and a side hole diameter of 5 mm when tested with the 1.5% and 3.0% simulants. However, no best catheter could be identified among TSCs when tested with the more liquid-like 0.5% simulant.

Greater TSC side hole diameter and nonparallel positioning was important for suctioning mucus simulants that are similar to mucus or sputum. The distance between side holes, end hole size, suction force, and duration of suctioning were not tested but could also have an effect on TSC performance.