Closed suction units are common in critical care and allow suction to be performed without disconnecting the ventilator circuit.

Different lengths of suction catheter are available for tracheostomy tubes and for endotracheal tubes. Using the wrong combination will cause ineffective suction or risk trauma with inappropriately deep catheter insertion. The alert tag on the tube (Fig 1) identifies the length of the catheter unit as suitable for a tracheostomy or endotracheal tube.

Always remove the catheter to its full extent after suctioning. This ensures that there is no unnecessary resistance to ventilation and that the suction catheter cannot be damaged. These devices are usually changed every 48-72 hours.