Airways and Intubation

Endotracheal intubation is the placement of a tube into the trachea to maintain a patent airway in those who are unconscious or unable to breathe independently. Compared to the use of pharyngeal airways (oropharyngeal or nasopharyngeal), benefits of an endotracheal airway include:

• Protection against aspiration and gastric insufflation
• More effective ventilation and oxygenation
• Facilitation of suctioning
• Delivery of anaesthetic and other drugs via the endotracheal tube (ETT)

Previously restricted to the anaesthetic and operating rooms, advances such as rapid sequence induction (RSI) have meant that intubation is often performed in emergency or pre-hospital settings.¹ These situations are by their nature high-risk and there is some evidence that pre-hospital endotracheal intubation in adult major trauma patients with head injury actually increases mortality.² Many confounding variables exist - experience levels, lack of monitoring equipment, difficulties pre-oxygenating patients etc - and the studies are retrospective but benefit should not be assumed.

Intubation is a technique that requires training, experience and regular updating to maintain competence. Anyone attempting it should also be capable of managing any complications that arise. GPs will vary in their ability: some will have developed a special interest during hospital training, gained postgraduate qualifications and may even perform regular anaesthetic lists; others will have an interest in pre-hospital and emergency care and may be involved in BASICS or ATLS to maintain relevant skills. The key principle is not to act beyond your personal level of competence.

Alternatives to intubation

• Laryngeal mask airway (LMA):
  • Widely used in UK in more than 50% of surgical patients.
  • Consists of an inflatable silicone ring attached diagonally to a flexible cushion filling the space around and behind the larynx, creating a low pressure seal between the tube and trachea without insertion into the larynx.
  • It can be used in an emergency setting by providers not trained in tracheal intubation and is an option in the management of a difficult airway where intubation has been unsuccessful.
  • It is not a definitive airway and provides limited protection only from gastric aspiration.
• Oesophageal Tracheal Combitube© (ETC):
  • The ETC is a double lumen tube combining an oesophageal tube with closed distal end linked by a short connection to a conventional tracheal tube.
  • It is designed for blind insertion and placement is determined by examination and auscultation and cuffs can be adjusted according to whether the trachea or oesophagus has been intubated.
  • It has been used amongst first responders in North America successfully³ but its use in the pre-hospital setting can also be associated with serious complications such as aspiration pneumonitis, pneumothorax and oesophageal rupture.⁴
• Tracheostomy

• Inability to oxygenate patient (SO₂<90%, PaO₂<55).
• Inability to ventilate patient (rising PaCO₂, respiratory acidosis, mental status change).
• Patient unable to protect airway.
• Anticipated clinical deterioration.

• Neck immobility or increased risk of neck trauma (for example, rheumatoid arthritis or suspected cervical spine injury) - consider fibreoptic intubation if available.
• Inability to open mouth (for example, scleroderma or surgical wiring) - consider nasal intubation or surgical airway.

Preparation

• Preoxygenate with 100% oxygen via well-fitting mask
• Consider premedications to counteract side-effects of intubation.
• If conscious, consider RSI

Preventing gastric aspiration

Always assume in an emergency setting that a patient has a full stomach carrying the risk of regurgitation and inhalation of gastric contents. If possible, liquid contents of the stomach are removed with a nasogastric or orogastric tube.
Cricoid pressure is applied from the time of loss of consciousness until a secure airway is in place. Pressure is applied directly in mid-line on the cricoid cartilage using tips of thumb and index finger while possibly applying counter-pressure from back of neck. This occludes the oesophagus again with the aim of reducing gastric aspiration although the evidence for this is disputed.¹¹

Patient position

• Patient aligned without lateral deviation of head or neck
• Head extended on neck with pillow under occiput. If cervical spine trauma is suspected, have assistant provide in-line immobilisation.
• Neck flexed to approximately 15 degrees on chest.

In infants under 2, the occiput naturally extends the head and the chin alone needs lifting into the 'sniffing' position.

Inspect mouth for loose teeth or dentures and remove. Suction any secretions or vomitus.

Intubation

Intubation attempts should not last longer than 30 seconds.

• Hold laryngoscope in left hand and ETT in right and introduce laryngoscope over right side of tongue, sweeping the tongue to the midline.
• Position the tip of the blade in the valecula (between the epiglottis and base of tongue) and lift upwards and away from yourself until the glottis is visualised.
• Exert traction along the axis of the handle - do not use the teeth or gums as a fulcrum as this will result in damage to teeth and/or gums.
• Introduce the endotracheal tube into the right corner of the mouth, passing it through the vocal cords with the cuff positioned and inflated just beyond the cords.
• Ventilate with high concentration oxygen and secure endotracheal tube.
• To assess tube position:
  • Look for symmetrical chest movement.
  • Listen over apices and base of lungs and stomach for equal breath sounds and no gastric breath sounds.
  • End-tidal carbon dioxide monitor attached to ETT.

Trouble shooting⁶

Consider:

• Dislodged tube
• Obstructed tube
• Pneumothorax
• Equipment failure

• Failed intubation and hypoxaemia:
  • Can ventilate with mask - seek senior help, defer intubation or consider alternative.
  • Can't ventilate - call for urgent assistance; if bag and mask ventilation maintaining oxygen saturations above 90% and there is adequate time, consider other options such as the use of a bougie to guide ETT placement or alternatives such as the use of LMA or Combitube© or fibreoptic induction or if not, cricothryoidectomy. See "failed airway" algorithm.⁵
• Aspiration and post-intubation pneumonia
• Pneumothorax
• Trauma from laryngoscope:
  • Teeth & soft tissues - avoidable with good technique.
  • Oedema - usually due to repeated attempts.
• Right mainstem intubation
• Oesophageal intubation - fatal if unrecognised
• Hypotension and arrhythmias
• Vocal cord avulsion

Avoiding problems

Potential problems in maintaining airway or performing intubation as suggested by presence of:

• Physical signs, e.g. short immobile neck, receding jaw, limited mouth opening, protruding or unhealthy teeth, large tongue, facial trauma.
• Injuries to cervical spine limiting movement.
• Possible airway obstruction, for example as result of severe facial trauma or burns to airway.
• Stridor at rest.

Anticipate difficult intubations and seek experienced assistance in advance of the intubation attempt if possible.