A tracheostomy (trach) tube is a curved tube that is inserted into a tracheostomy stoma (the hole made in the neck and windpipe). There are several different brands of tracheostomy tubes, but all have similar parts. In double-cannula tubes, the inner cannula is inserted and locked in place after the obturator is removed; it acts as a removable liner for the more permanent, outer tube. The inner cannula can be withdrawn for brief periods to be cleaned. The main parts of a double cannula tracheostomy tube are the outer tube (or cannula), the inner tube (or cannula) and the obturator. The obturator is used only to guide the outer tube during insertion and is removed immediately after the outer tube is in place. The outer tube has ties to secure it in place around the person’s neck. Many of the smaller plastic tracheostomy tubes do not have an inner tube. They are called single-cannula tubes.
For infants and small children, the trach tube is usually a single-cannula plastic tube and is generally not cuffed (even if mechanical ventilation is required). The tube size and type is determined by the doctor depending on the reason for the trach tube as well as the size, age and medical needs of the individual. Tracheostomy tubes can be made of metal, plastic or silicone. Plastic and silicone tubes are increasingly popular because they are lightweight and there is less crusting of secretions. Tracheostomy tubes come in many varieties, including cuffed, uncuffed and fenestrated. A cuff is a soft balloon around the distal (far) end of the tube that can be inflated to allow for mechanical ventilation in patients with respiratory failure. The cuffs are inflated with air, foam or sterile water. There are several types of cuffs. The low volume cuff is similar to a balloon; a high volume cuff is barrel-shaped. The high volume cuff may be better to avoid complications such as stenosis, because it spreads the pressure out, rather than pushing on one spot in the airway. Tight to shaft (TTS) balloons by Bivona are instilled with sterile water. These work well for children who can be off the ventilator at times. When the balloon is deflated, the tube allows air around tube for vocalization. In small children, cuffed tubes may not be needed, however, in older children a low-pressure cuff may be needed to achieve an adequate seal. For children who are not ventilator dependant, the tracheostomy tube should allow some airflow around the tube to avoid damage to the tracheal wall and to permit speech. Fenestrated tubes have an opening in the tube that permits speech through the upper airway when the external opening is blocked, even if the tube is too big to allow airflow around the outer cannula. Fenestrated tubes are not recommended for small children, because they can obstruct the opening with granulation tissue. The opening of the hole must be at a correct angle to prevent problems. Also, in an emergency, a solid inner cannula must be inserted in order to ventilate a child through the trach.