Figure 5.

Setup for the lung model for measurement of suction pressure. The test device consisted of a Plexiglas bottle with a connected water manometer. The endotracheal (ET) tube was inserted in the bottle through an opening at the top and the opening was sealed airtight thereafter. The tip of the suctioning catheter was introduced through the ET tube to 2 cm below the distal end of the ET tube. The catheter was then connected to a suction pressure of -400 mmHg at the wall inlet. The pressure generated in the bottle was measured as the difference between the water levels 'A' and 'B'.