The new NL tracheal suction catheter.

When a tube with a vacuum is approached to the surface of a liquid, a suction cone is formed and the liquid is sucked into the tube. In the new NL tracheal suction catheter, this suction cone effect is used to transport secretion into its depressed suction holes. The catheter is angle-tipped and has a U-shaped depression around a single side hole at the angle. Four large holes near the edge of the tip hole are shown to be just as effective in reducing the pulling force from the tip hole as the depression around the side hole. The new catheter was compared with three commercially available suction catheters with regard to the maximum damaging effect and the suction efficacy. The force from each suction hole pulling a flat metal base was reduced from 3 to 33 times and the efficacy in sucking was increased in relation to the other catheters when egg-white was used as model for mucus. Angle-tipped catheters are orientation-dependent. The NL catheter was the least orientation-dependent of the three angle-tipped catheters tested. Histologic examination of the mucus sucked during a clinical test showed that the NL catheter caused less tracheobronchial damage than did the Rüsch catheter.