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Anatomy and Physiology of tracheostomy Structure of trachea

Anatomy and Physiology of Tracheostomy

Tracheostomy sometimes called tracheotomy is the creation of an opening directly into the trachea (windpipe) in the neck for the purpose of assisting breathing. While tracheotomy is used to be done as an emergency, Now days is to be done more on an elective basis to protect the airway, It’s better clean the airway and to provide more oxygen to the lungs

The trachea is easily accessible at the bedside. It provides ready access for emergency airway cannulation  and for chronic airway access after the laryngeal surgery. More commonly, tracheostomy tubes to be  placed to allow removal of a translaryngeal endotracheal tube. Tracheostomy tubes have plays as an important role on effect of respiratory physiology.

The most recent and methodological robust studies indicate that these tubes are reduce resistive and elastic work of breathing, when compared to endotracheal tubes. This is a result of tracheostomy tubes lessening inspiratory and expiratory airways resistance and intrinsic positive end-expiratory pressure.

Anatomy and Physiology of Tracheostomy

Anatomy

  • Back of the mouth and nose the air passages form the pharynx, which continues into the larynx (voice box). The larynx may be felt as the Adam’s apple in front of the neck.
  • The lower respiratory tract starts from the vocal cords. Inferior to the vocal cords, the rigid cricoid cartilage encases a 1.5–2.0-cm region known as the subglottic space.
  • Access the space is possible via the cricothyroid ligament, a membrane that runs from the thyroid cartilage inferiorly to the cricoid cartilage.
  • Inferior to cricoid is the trachea is a cylindrical tube that extends inferiorly and slightly posteriorly.
  • The trachea is made up of 18–22 C-shaped rings consisting of rigid cartilage anteriorly and laterally, and a membranous posterior portion.
  • In the average adult, the distance from cricoid to carina is approximately 11 cm in length, with a range of 10–13 cm.
  • On average, the trachea is 2.3 cm in width and 1.8 cm from posterior membrane to the anterior cartilaginous aspect.
  • The thyroid gland situated in front of the trachea. The esophagus (foodpipe) lies behind it
  • The trachea is wider in men than in women.
  • In examining the landmarks of the neck, The trachea is protected by strap muscles (sternohyoid, sternothyroid, sternocleidomastoid) and bony structures (manubrium and sternum) Furthermore, the trachea is positioned posterior to a number of blood vessels and the thyroid isthmus.
  • The innominate artery passes through the front of the lower tracheal rings of the trachea. This artery is a branch of the aorta (the major artery coming from the heart) and gives rise to the arteries to the right side of the brain and right arm
  • Bronchial Branches of the bronchial, inferior thyroid, innominate, and subclavian arteries provide the blood supply to the trachea.

Physiology

  • The trachea is a rigid structure, which is formed from rings of cartilage to ensure that the airway always remains open.
  • Its function is to maintain and protect the airway from  foreign body.
  • The trachea is lined with mucus glands, which humidifies atmospheric air as it passes through the trachea and catches small particles before they reach to the lungs.
  • The trachea also has specialized hair like structures called cilia which move rhythmically to sweep mucus and particles back up to the throat.
  • The trachea has many defensive cells that kill organisms which enter the trachea
  • Nerves are supplied to the trachea that are part of the cough reflex that helps get rid or irritants
  • A tracheostomy by-passes the upper airway means that the normal function of the nose and mouth are hamppered.
    • Warming of air
    • Humidification of air
    • Filtering of air, including dust particles and micro-organisms
    • Communication/vocalising
    • Swallowing, nutrition & hydration
    • Smell