Intubation procedure: Video

1. Maintenance of a patent airway:

  • When an awkward intraoperative position is required (eg. lateral decubitus, prone, sitting)
  • When the airway is inaccessible (eg. during head and neck operations)
  • When difficulties with the face mask are anticipated (eg. in grossly obese or edentulous patients or those with unusual facial features).

2. Protection of the airway: from contamination by blood, pus, debris, or stomach contents

3. Controlled ventilation

Technique of laryngoscopy and Tracheal intubation:

1. Position: The patient is positioned supine with the head resting on a pillow, in the so-called 'sniffing the morning air position' (flexion of the lower cervical spine and extension of head at atlanto-occipital junction). The position aligns the oral, pharyngeal and laryngeal axis so that the pathway from the lips to the glottis is nearly a straight line.

2. Laryngoscopy: The laryngoscope is held in the left hand, whilst the right hand is used to stabilize the head and open the mouth. The laryngoscope is inserted into the right side of the patient's mouth avoiding the incisor teeth and pushing the tongue to the left. The tip of the blade is advanced in the midline over the back of the tongue until the epiglottis comes into view. The tip of Macintosh laryngoscope blade should be positioned above the epiglottis, into the vallecula (the space between the base of tongue and the epiglottis). The tongue and pharyngeal soft tissues are then lifted, pulling the epiglottis up without directly touching it, exposing the glottic opening. You should use your arm and shoulder to lift the laryngoscope handle in an anterior and forward direction (along the long axis of handle containing the batteries). The tendency to lever the laryngoscope against the upper incisor teeth or upper gum should be avoided to prevent trauma.

The Miller blade, which is straight, is less commonly used. The tip of Miller blade is passed beneath the laryngeal surface of the epiglottis and the epiglottis itself is then lifted to expose the vocal cords. There is more risk of trauma to the epiglottis and stimulation of the laryngeal surface of the epiglottis.

3. Intubation: The size of the tracheal tube used depends on the patient's age and body build. Usually an 8mm internal diameter cuffed tube is used for women and a 9mm tube for men. The tube is held in the right hand as one would hold a pencil and advanced through the oral cavity through the right corner of the mouth and then through the vocal cords. External pressure on the cricoid or thyroid cartilage may be required to help visualize the laryngeal inlet. The proximal end of the tube cuff is placed so that the cuff is below the vocal cords, and the length markings on the tube are noted in relation to the patient's lips. The cuff is inflated to obtain a seal in the presence of 20-30 cm H20 pressure of gas in the breathing system.

4. Verification of position of tube: The next step is to verify the position of the tracheal tube. The best method to determine the position of the tube is by detection of carbon dioxide in expired gas. It is possible for gas in the stomach to contain carbon dioxide but this will only be present in the first few 'breaths'. Visulaization of the end of the tube advancing through the vocal cords is also taken as a sign of correct palcement. However, tubes may be displaced after 'correct' insertion. Auscultation of both lung fields in the axilla and over the stomach may also be used to confirm correct placement, but is less reliable. Asymmetrical breath sounds may indicate that the tip of the tube lies in one or other of the main bronchi (usually the right_. The tube should be withdrawn until breath sounds are heard bilaterally.

Complications of orotracheal intubation include:

  • Injury to lips, tongue or teeth
  • Injury to larynx (especially the arytenoid cartilages and the vocal cords)
  • Tracheal mucosa tear
  • Sympathetic stimulation

Attempting laryngoscopy or tracheal intubation in lightly anesthetized patients who are not fully relaxed can result in laryngospasm, coughing and bronchospasm. The laryngoscope should be removed, face-mask ventilation should be continued and anesthesia deepened or more muscle relaxant given to achieve adequate conditions. A peripheral nerve stimulator can be used to ensure complete neuromuscular blockade before commencing laryngoscopy and intubation.[endtext]


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