Design and function of tracheal suction catheters.

Tracheal suction catheters damage the mucosa of the airway, due to both the pull from the vacuum and insertion of the catheter. The pull of the vacuum from a suctioncatheter was measured on a Mettler balance. An open side hole reduced the pull by around 90% and a distance of 1 mm gave a reduction of around 90%. The combination of one side hole and a 1 mm distance gave a 99% reduction of the pull. The difference between one or more side holes was measured. The suction efficacy was higher with a single side hole than with several side holes. On the basis of these measurements and a review of the literature, the principles were outlined for the construction of a suction catheter which provided maximum suction efficacy and caused minimum damage: (1) a moderate to strong vacuum was to be used; (2) the catheter was to have a single hole at the tip and a single side hole placed at the convex side of the angle; (3) both side hole and tip hole should be so constructed that the holes were kept at a distance from the mucosa; and (4) the tip should be angulated.