Airway Management in Surgery
Airway Management
Basic hierarchy of airways:
| Hierarchy | Technique / device |
|---|---|
| Basic airway manoeuvres |
|
| Airway adjuncts |
|
| Supraglottic airways (SGA) |
|
| Definitive airway |
|
Definitive Airway
A definitive airway is defined as an airway device positioned below the vocal cords to provide:
- Airway protection from gastric aspiration
- Effective ventilation and oxygenation
- Delivery of positive pressure ventilation
There are 2 main types of definitive airway:
- Successfully placed endotracheal tube
- Surgical airway (cricothyrotomy or tracheostomy)
SGAs like laryngeal mask airway and I-gel ® are often considered secure airways, but not a definitive airway.
SGAs sit above the vocal cords and do not isolate the trachea from the oesophagus. Therefore, they do not reliably protect the airway from aspiration and do not guarantee a secure seal for positive pressure ventilation.
Choice of Airway in Surgery
Endotracheal intubation remains the gold standard for airway protection during surgery
It is important to be aware of the absolute indications of endotracheal intubation:
- Patients who are not fasted (e.g. emergency surgery)
- Risk of aspiration (e.g. obese patients, surgery that increases intra-abdominal pressure – e.g. laparoscopic surgery)
- Anticipated airway compromise
- Surgery requiring muscle relaxation (e.g. neurosurgery, thoracic surgery, abdominal surgery)
- Surgery that shares the airway (e.g. ENT, maxillofacial surgeries)
If endotracheal intubation is not necessary and a short, elective procedure is planned, an SGA may be sufficient for airway management. However, the choice between SGA and endotracheal intubation should always be individualised based on patient-specific risk factors (e.g., aspiration risk), surgical requirements, and anticipated airway difficulty.
Endotracheal Intubation
Procedure
This is a simplified, concept-based procedure listing:
- Prepare equipment – choose the correct ET tube size and laryngoscope
- Pre-oxygenation with 100% oxygen
- Administer induction agents and ensure the patient’s jaw is relaxed
- Insert the laryngoscopy blade → displace the tongue aside → advance the blade until the epiglottis is visible below it
- Raise the epiglottis to reveal the vocal cords (this is achieved by lifting the blade forward and upward)
- Insert the ET and advance it past the vocal cords (ensure the cuff is below the cords)
- Remove the larynsocpe
- Inflate the cuff
- Attach the tube to the ventilator and secure the tube
Direct and video laryngoscopy are both widely used techniques to visualise the vocal cords for endotracheal intubation
- Direct laryngoscopy requires the operator to visually align and look directly down the patient’s airway by inserting the laryngoscope blade into the mouth to expose the vocal cords. This technique relies on creating a nearly straight line of sight between the operator’s eye and the glottic opening.
- Video laryngoscopy, by contrast, uses a camera embedded at or near the blade tip to display an enlarged glottic view on a screen. This allows the operator to see “around corners” via the monitor, providing a different, often improved angle of the airway structures without needing direct line-of-sight visualisation.
Evidence suggests that video laryngoscopy generally improves first-pass intubation success and reduces complications, especially in difficult or emergency airways, compared to direct laryngoscopy.
Confirmation of Endotracheal Intubation
Gold standard: end-tidal carbon dioxide (EtCO2) monitoring using waveform capnography
- Continuous detection of exhaled CO2 over at least several breaths confirms tracheal (not oesophageal) intubation
Other methods:
- Auscultation of breath sounds across both lung fields
- Direct visualisation of endotrahcael tube markers (~20-24cm at the teeth for adults, NB this varies with patient size)
Complications
Acute complications (can occur in anyone):
- Failed intubation
- Trauma and injury (e.g. dental damage, lip / tongue laceration, vocal cord injury, arytenoid dislocation)
- Oesophageal intubation
- Endobronchial intubation (tube inserted too deeply, resulting in single-lung ventilation)
- Bronchospasm / laryngospasm
Chronic complications (usually result from prolonged / repeated intubation):
- Chronic sore throat / dysphagia (from mucosal injury)
- Tracheal stenosis / granulation tissue (from irritation)
- Tacheomalacia (weakening of tracheal cartilage)
- Vocal cord paralysis or scarring
- Tracheoesophageal fistula (rare but serious)
Difficult Airway
Indicators of Difficult Airway
| Category | Features |
|---|---|
| Mouth |
|
| Neck |
|
| Facial features |
|
Management
A difficult airway can result in failed endotracheal intubation.
Key alternatives to endotracheal intubation:
| Approach / method | Description |
|---|---|
| SGA |
|
| Emergency surgical airways | Mainly used in CICV scenarios:
Cricothyrotomy is quick and relatively easy to perform, usually used for emergency access. Tracheostomy is usually reserved for long-term airway access. |