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Friday, June 6, 2014

What are the parts of a tracheostomy tube?

In 1543, Andreas Vesalius (1514-1564) described how he breathed for a animals by blowing into a reed inserted into their necks through a tracheal opening. This was one of the first descriptions of a tracheostomy tube.  By the 19th century the operation of tracheotomy was perfected, and tracheostomies resembled those used today.

Since we have already discussed the procedure of tracheotomy and the basic indications for them, this post will cover the basics of the tracheostomy tubes themsevles.

1.  What is a tracheostomy tube?  This is a small, hollow tube inserted into a stoma created by a tracheotomy.

2.  What does a tracheostomy tube consist of?  What does it come with?  My humble answer:  Most trachs come with three parts:  Outer cannula, Inner cannula, and obturator.  The outer cannula holds the stoma open and it has neck plates that extend on both sides so it can be secured by a velcro trach collar or trach ties. The inner cannula has a lock to keep it from being coughed out.  It is easily removed so it can be cleaned.  Essentially, the inner cannula makes cleaning easier.  The obturator is used to insert the trach.  It slips into the tube and helps the doctor guide the trach into place.

3.  What is a fenestrated tracheostomy?  What are the benefits and disadvantages of it?  It's a trach with holes or fenestrations in the outer cannula that allow air to pass into the upper airway so the patient can cough to remove secretions and talk.  Basically, it allows normal breathing and the ability to speak. It allows a trial of normal breathing and normal talking before a trach is removed, and may also necessary for long term trachs.  To take advantage of the fenestrations the inner cannula must be removed and the cuff (if there is one) deflated.

4.  What are the different types of tracheostomies?  What trach to use depends on the patient, and trach should be 3/4 the diameter of the patient's trachea.  The following are the types of tracheotomy tubes according to John Hopkins:
  • Cuffed with inner cannula:  The inner cannula may be either disposable or reusable.  Cuff should be inflated only for positive pressure breaths.  It must be deflated to use a speaking valve.  
  • Cuffless tube with inner cannula:  T'he inner cannula may be either disposable or reusable.  Good trach for people who don't need to be on a ventilator.
  • Fenstrated cuffed tracheostomy tube:  This increases the risk for aspiration due to the fenestrations.  The fenestrations also make it difficult to ventilate these patients.  However, good for weaning off trachs and for some patients who want to use a speaking valve. This type of tube is good for long term ventilator patients.
  • Fenestrated cuffless tracheostomy tube:  Only used for patients who have difficulty using a speaking valve with the other trach tubes. There are risks associated with using fenestrations, such as aspiration and glanulation formation around the site of the fenestrations
  • Metal tracheostomy tubes:  Rarely used.  Cannot use during MRI, and will cause alarm during airport security checks.  
5.  What is an inner cannula?  An inner cannula is a cannula inserted into the trach.  It allows for easy maintenance of the trach especially if there are thick secretions.  It also has a universal adaptor on it so the patient can be connected to a Ambubag or ventilator circuit to receive positive pressure ventilation.  

6.  How can a person with a trach speak?  The patient can speak either if the tube has a speaking valve or if the patient simply covers the opening with a finger.  For this to occur, the outer cuff must be fenestrated.  

7.   What is a tracheostomy cuff? When is it needed and when should it be inflated?  When should it be deflated?   A cuff will irritate the trachea, and therefore should not be used unless needed for positive pressure breaths. It also allows a place for secretions to pool, and therefore increases the risk of micro-aspiration of secretions, increasing the risk for lung infections.  The only reason a cuffed tracheostomy is necessary is when positive pressure breaths are indicated. When a person is receiving positive pressure breaths, whether by AMBU-bag, BiPAP, or mechanical ventilator, it is necessary to inflate the cuff. This is necessary to prevent air from leaking around the tube in order so the patient receives an adequate breath or tidal volume.  If a patient is not receiving positive pressure breaths the cuff, if there is one, should be deflated.  For patients who require positive pressure ventilation, the lowest possible cuff pressure should be used to inflate the cuff, and it should be deflated four times a day to prevent tracheal necrosis

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