Airway devices [advanced]

Nasopharyngeal airway

• Flexible rubber tube which goes through the nose and ends at base of tongue (an adjunct to help keep airway open)
• An oxygen mask or bag-mask ventilation can be applied over the top if needed
• Function: prevents tongue covering epiglottis in patients with reduced GCS. It is better tolerated than oropharyngeal airways in more alert patients.
• Size: 6-7mm diameter for most adults; tube diameter should be similar to nostril size
• Insertion technique:
  • Lubricate the nasopharyngeal airway with water-soluble jelly
  • Insert into the nostril (preferably right) horizontally along the floor of the nose with a slight twisting action (aim towards the back of the opposite eyeball)
  • Confirm airway patency

Oropharyngeal airway (Guedel)

• Rigid plastic tube which sits along top of oral cavity and ends at base of tongue (an adjunct to help keep airway open)
• An oxygen mask or bag-mask ventilation can be applied over the top if needed
• Function: prevents tongue covering epiglottis in patients with reduced GCS
• Size: should be similar to distance between the incisors and the angle of jaw; size 3 (orange) for medium adult
• Insertion technique:
  • Ensure no foreign bodies in the mouth
  • Lubricate the oropharyngeal airway
  • Insert into the mouth upside-down (reduces risk of pushing tongue back) – do not continue if patient gags
  • Once tip is around the hard-soft palate junction, rotate 180˚ and advance the rest of the way
  • Confirm airway patency

Supraglottic airway (usually i-Gel)

• Flexible plastic tube with a cuff on the end which sits over top of larynx. Provides some protection against aspiration but does not fully secure airway and can only withstand a small amount of positive pressure ventilation.
• Can be attached to ventilation bag in respiratory arrest; or, during surgery, to ventilator which allows spontaneous ventilation ± low-level positive pressure ventilation supplementation
• Function: airway protection during anaesthetic for surgery (if no risk of aspiration and a muscle relaxant is not required); respiratory arrest; if endotracheal intubation is indicated but fails, or the clinician is not trained in intubation   
• Size: 4 (green) for average adult
• Gather equipment

• Insertion technique:
  • Give medications if required
  • Lubricate outer airway
  • Position patient – neck flexed to 15˚, head extended on neck (i.e. chin anteriorly), no lateral deviation 
  • Standing behind the patient, hold the tube like a pen and insert into the mouth (cuff opening inferiorly), sliding the outer cuff along the palate
  • Push back over tongue until it reaches the posterior pharyngeal wall
  • Apply pressure to force it backwards and downwards until it reaches the back of the hypopharynx
  • The teeth should be between the two black lines on the airway
  • Attach ventilation bag/machine and ventilate (~10 breaths/minute) with high concentration oxygen. Observe chest expansion and auscultate to confirm correct placement. 
  • Consider applying end-tidal CO₂ monitor to confirm placement and then secure with bandage or tape

Endotracheal tube

• Flexible plastic tube with cuff on end which sits inside the trachea (fully secures airway – gold standard)
• Attached to ventilation bag/machine
• Function: ventilation during anaesthetic for surgery (if muscle relaxant is required, long case, abdominal surgery, or if head positioning may be required); if patient cannot protect their airway (GCS <8, aspiration risk, muscle relaxation); potential airway obstruction (airway burns, epiglottitis, neck haematoma); inadequate ventilation/oxygenation (e.g. COPD, head injury, acute respiratory distress syndrome)
• Rapid sequence induction intubation = procedural variant using rapid anaesthetisation with cricoid pressure to prevent aspiration while airway is quickly secured – used for patients at risk of aspiration, e.g. non-fasted patients
• Size: 8mm diameter for men, 7mm diameter for women
• Gather equipment

• Laryngoscope technique:
  • Give medications if required
  • Pre-oxygenate patient with high flow oxygen for 3-5 minutes
  • Position patient – neck flexed to 15˚, head extended on neck (i.e. chin anteriorly), no lateral deviation
  • Stand behind the head of the patient
  • Open mouth and inspect: remove any dentures/debris, suction any secretions
  • Holding laryngoscope in left hand, insert it looking down its length
  • Passing the tongue
    • Slide down right side of mouth until the tonsils are seen
    • Now move it to the left to push the tongue centrally until the uvula is seen
  • Advance over the base of the tongue until the epiglottis is seen
• Insertion technique:
  • Apply traction to the long axis of the laryngoscope handle (this lifts the epiglottis so that the V-shaped glottis can be seen)
  • Insert the endotracheal tube via the groove of the laryngoscope so that the cuff passes the vocal cords (male 22-24cm, female 20-22cm)
  • Remove laryngoscope and use syringe to inflate the tube’s cuff with the minimum amount of air required for an effective seal
  • Attach ventilation bag/machine and ventilate (~10 breaths/minute) with high concentration oxygen. Observe chest expansion and auscultate to confirm correct placement. 
  • Consider applying end-tidal CO₂ monitor to confirm placement 
  • Secure the endotracheal tube with tape

NB: if it takes more than 30 seconds, remove all equipment and ventilate patient with a bag-mask and high flow oxygen until ready to reattempt intubation. 

Tracheostomy

• Surgical hole made in trachea, through which a tracheostomy tube is passed
• Attached to ventilation bag/machine
• Function: a tracheostomy is performed for long-term ventilation in intensive care
• NB: a needle or surgical cricothyroidotomy is different and is used in the emergency setting when an acute upper airway obstruction is preventing endotracheal intubation 

Sedation, paralysis, ventilation

• If a patient has had a muscle relaxant they need to be ventilated
• Otherwise the need for ventilation/supplementation of breathing depends on the degree of sedation (a low amount of sedation can allow spontaneous ventilation)
• Patients need to be sedated to a certain degree to allow intubation
• A short-acting muscle relaxant helps endotracheal intubation