Author: Matthew Frise
Management of the upper airway, which runs from the mouth and nose to the carina, has two fundamental aims:
- Maintenance of a patent passage for free movement of gas between the atmosphere and the aveoli.
- Prevention of soiling of the lungs by vomitus or other material.
Manual manipulation of the airway
Suction
- If vomit, secretions, or other debris is present in the oropharynx, these can be removed with a wide-bore rigid Yankauer sucker, to relieve obstruction and prevent aspiration.
- A flexible suction catheter can also be passed through an oro- or nasopharyngeal airway.
- Care must be taken not to cause mucosal injury and bleeding; provoking vomiting or laryngospasm are also risks in semi-conscious patients.
Oropharyngeal airway
- In an unconscious patient, obstruction may occur in an anatomically normal airway owing to loss of muscle tone with collapse at the level of the soft palate, epiglottis or tongue base. An oropharyngeal (Guedel) airway may restore airway patency sufficiently for spontaneous or bag-mask ventilation.
- The length should approximate to that from the angle of the mandible to the incisors; insert with the concavity facing the palate and rotate 180° into final position (Figure 112.3).
- Obstruction may be worsened if the epiglottis is pushed against the laryngeal inlet or the tongue displaced posteriorly; laryngospasm may also result – try a smaller size or nasopharyngeal airway if so.
Nasopharyngeal airway
- As an alternative to the oropharyngeal airway, a soft lubricated tube may be inserted into the nostril. Remember that that the floor of the nose is horizontal.
- Often better tolerated in patients with a reduced conscious level than the oropharyngeal airway.
- Epistaxis may result, and if too long, laryngospasm and vomiting are risks, as with an oropharyngeal airway.
- Contraindicated in patients with known or suspected base of skull fracture.
Bag-mask ventilation
- Rather than an airway management technique per se, this is a treatment for inadequate ventilation, usually in an unconscious patient with upper airway obstruction.
- Inadequate ventilation due to a poor seal can be improved by repositioning or a two-handed technique (Figure 112.4); bearded and edentulous patients can be a particular management problem. Keep well-fitting dentures in place.
- Some devices feature a positive end-expiratory pressure (PEEP) valve, which is very useful for managing airway obstruction due to laryngospasm.
- Over-ventilation may cause barotrauma, pneumothorax or cardiovascular compromise and should be avoided; gastric insufflation increases the risk of vomiting and aspiration. Aim for a tidal volume of 6–10 mL/kg.
Supraglottic airway: laryngeal mask airway (LMA™) and i-gel®
- The LMA is inserted blindly into the oropharynx to sit over the laryngeal inlet, with an inflatable low-pressure seal. It is not a definitive airway and does not allow ventilation with high airway pressures nor provide the same level of protection against soiling as a cuffed endotracheal tube (ETT).
- Even in inexperienced hands the rate of successful insertion is high, making LMAs very useful in the emergency setting. ALS guidance now recommends that an LMA is preferred initially over attempted endotracheal intubation in the management of cardiorespiratory arrest.
- The i-gel® – like an LMA but with a soft, non-inflatable cuff – is increasingly used in preference to the classical LMA. Familiarize yourself with the particular supraglottic airways available on your cardiac arrest trolleys in advance of needing one.
- Supraglottic airways are not helpful if there is obstruction at or below the larynx.
A GCS of ≤8 is often taken as an indication to intubate a patient for airway protection, but this practice originates from work in trauma patients. Any degree of impairment of consciousness is associated with increased risk of aspiration pneumonia, though many medical patients in this category may reasonably be managed in a closely monitored environment with equipment and personnel on hand to intervene if necessary. Testing the gag reflex is not useful for predicting aspiration risk.
Endotracheal intubation provides a definitive airway, permitting mechanical ventilation (with high airway pressures if needed) and protection from aspiration, and is therefore considered a gold standard. However, there are several caveats:
- Cardiac arrest – guidance now emphasizes the harm that may result from interruption of cardiac massage by repeated intubation attempts; the LMA is preferred unless a critical care physician or anaesthetist is immediately on hand.
- Mechanical UAO – airway anatomy may be seriously distorted, leading to difficult intubation. The decision to sedate, paralyse and attempt endotracheal intubation with direct laryngoscopy should only be taken by a clinician with appropriate expertise.
The comatose patient – if airway protection is the primary aim, intubation may be straightforward, but measures to reduce the risk of aspiration during the procedure should be employed. These include cricoid pressure during a rapid-sequence induction (RSI) and placement of a nasogastric tube to empty the stomach beforehand; though this has the potential itself to provoke vomiting and aspiration.
If intubation is performed, it is essential to confirm correct tube placement by a combination of methods rather than any one in isolation:
- Direct visualization – the tube is seen to pass between the vocal cords.
- Measurement of expired carbon dioxide by capnography – many resuscitation trolleys include indicator devices that can be attached to the endotracheal tube to detect carbon dioxide. Beware false-positive results from initial breaths after oesophageal intubation with an insufflated stomach, and false-negative results in cardiac arrest.
- Auscultation over the epigastrium and the thorax bilaterally.
- Portable CXR – to confirm where the tip of the tube lies and exclude complications such as pneumothorax.
Complications of endotracheal intubation:
- Failure
- Inadvertent oesophageal intubation – devastating if unrecognized
- Laryngeal trauma
- Aspiration
- Cardiovascular instability from laryngeal stimulation and anaesthetic drugs
- Post-extubation airway obstruction
- Laryngeal and tracheal stenosis (late)
The Combitube (oesophageal-tracheal double-lumen airway) has been developed to have the benefits of a cuffed ETT but with easy insertion. It is blindly inserted into the oropharynx and ventilation can be delivered via either of two ports, depending on where the device has settled. If unfamiliar with this device it is better to use an LMA.
Surgical techniques to establish an airway are appropriate in the acute setting if other approaches have failed or are contraindicated, or in the presence of upper airway obstruction that is unlikely to resolve quickly. A formal surgical tracheostomy may also be fashioned if there is an anticipated need for prolonged mechanical ventilation or tracheal toilet, and avoids the need for sedative and analgesic medication to promote ETT tolerance. For management of the patient with complications relating to an existing tracheostomy, and details of emergent surgical airway techniques, see Chapter 59 which discusses the approach to the patient with upper airway obstruction.