Airway obstruction, stenosis and tracheostomy

Definition / Overview

Acute airway obstruction in the adult is a time-critical emergency in which the interval between recognition and secured airway can be measured in minutes. The OHN surgeon is frequently the clinician with the greatest anatomical and technical expertise for managing the obstructed airway, and must be able to lead or contribute to an interdisciplinary team response that spans the emergency department, operating theatre, intensive care unit and ward.

The fundamental principle is oxygenation first: any intervention that reliably maintains oxygen delivery to the patient is preferable to a technically elegant approach that fails. A sequential, pre-planned strategy from least to most invasive prevents reactive, disorganised escalation under pressure.

Pathophysiology and Aetiology

Mechanisms of Obstruction

• Supraglottic: epiglottitis (bacterial or radiation-induced), angioedema (hereditary or drug-induced, classically ACE-inhibitor), peritonsillar or parapharyngeal abscess, Ludwig's angina, tongue-base haematoma, supraglottic tumour
• Glottic: bilateral vocal fold immobility (post-thyroidectomy, bilateral RLN invasion), laryngeal trauma, acute laryngeal fracture, glottic tumour, paradoxical vocal fold movement (differentiated by flow-volume loop and awake laryngoscopy)
• Subglottic / tracheal: laryngotracheal stenosis (post-intubation, post-tracheostomy, idiopathic), extrinsic tracheal compression (goitre, mediastinal mass, haematoma post-thyroidectomy), tracheomalacia, foreign body
• Multilevel: head and neck malignancy with pharyngeal and laryngeal involvement; burn inhalation injury

Severity Determinants

• Static vs. dynamic: fixed stenoses behave differently from dynamic lesions (tracheomalacia worsens on forced expiration; variable extrathoracic lesions worsen on inspiration)
• Rate of progression: rapidly progressive obstruction (angio-oedema, haematoma) demands immediate surgical airway readiness even before complete obstruction supervenes
• Collateral reserve: a patient with pre-existing COPD or obesity has far less physiological reserve than a healthy adult; time-to-desaturation after apnoea is shortened
• Compensatory posture: the patient sitting upright, leaning forward, refusing to lie flat is signalling impending decompensation and must not be forced supine prematurely

Clinical Assessment

History

• Onset and trajectory: sudden (foreign body, angio-oedema) vs. progressive over hours/days (supraglottitis, deep neck infection, malignancy)
• Precipitants: recent medication change (ACE inhibitor), dental procedure (Ludwig's angina), neck surgery (haematoma), radiation history (chondroradionecrosis, radiation oedema), trauma
• Symptoms: stridor (inspiratory = supraglottic/glottic; biphasic = subglottic/tracheal), voice change (dysphonia, hot-potato voice), dysphagia, drooling (supraglottitis, abscess), odynophagia
• Prior airway history: previous difficult intubation, tracheostomy, neck dissection, laryngeal surgery, relevant craniofacial anatomy

Examination

Assess in the position the patient has chosen; do not force a position change that may precipitate complete obstruction.

Flexible Nasendoscopy

Performed only if the patient is stable enough to tolerate it (generally sitting, cooperative, not in extremis). Provides direct visualisation of:

• Supraglottic anatomy and oedema pattern
• Vocal fold mobility and glottic aperture
• Subglottic and proximal tracheal lumen (limited)

Do not perform topical anaesthesia of the larynx in an unstable patient: reflexive cough or laryngospasm may convert a partial obstruction to a complete one.

Investigations

Immediate Priority

• Continuous SpO₂ monitoring and ECG
• Arterial blood gas: hypercapnia ($\text{PaCO}_2 > 50\,\text{mmHg}$) indicates ventilatory failure and demands immediate airway intervention, not watchful waiting
• FBC, CRP, blood cultures: if infective aetiology suspected
• Complement C3/C4 and C1-esterase inhibitor level: if hereditary angio-oedema suspected

Imaging

• Lateral soft-tissue neck X-ray: "thumb sign" (epiglottitis), "steeple sign" (subglottic narrowing); quick but limited sensitivity
• CT neck and chest with IV contrast: gold standard for defining level, length and degree of airway stenosis, presence of abscess, extrinsic compression or vascular abnormality; obtain only if the patient is stable and the airway can be monitored throughout
• CT angiography: if haemorrhage or vascular mass is the aetiology
• Flow-volume loop: differentiates fixed from variable obstruction; variable extrathoracic lesions flatten the inspiratory limb; variable intrathoracic lesions flatten the expiratory limb; only applicable in cooperative, non-urgent presentations

Management

Immediate Stabilisation

1. Position: upright; do not force supine
2. Supplemental oxygen: high-flow 15 L/min via non-rebreather mask; note that high-flow oxygen will maintain saturation despite severe obstruction and may mask worsening until precipitous collapse
3. Avoid stimulating procedures in unstable patients (IV cannulation, NG tube, forced examination)
4. Call for help immediately: senior anaesthetist, OHN surgeon, theatre team; early activation avoids the chaos of reactive escalation
5. Prepare the team and equipment: two large-bore IV cannulae if tolerated; have suction, direct laryngoscope, video laryngoscope, supraglottic airway, cric kit and tracheostomy kit open and immediately available
6. Medical temporising measures where appropriate (see below)

Medical Temporising Measures

The Airway Decision Framework

The critical juncture is determining where, how and by whom the airway will be secured. This is a dynamic decision based on degree of obstruction, rate of progression, likelihood of successful endoscopic intubation, and team expertise.

ASSESS DEGREE OF OBSTRUCTION
 |
 PARTIAL OBSTRUCTION COMPLETE OBSTRUCTION
 SpO₂ maintainable Cyanosis / apnoea
 | |
 Can you visualise the glottis? Immediate surgical airway
 |
 YES NO (cannot intubate)
 | |
Attempt RSI Attempt supraglottic airway
with video (LMA / iGel) +/- FOI via SGA
laryngoscopy |
 | If ventilatable: plan
 Success? awake tracheostomy or
 controlled OR intubation

Airway Techniques: Spectrum of Interventions

1. Basic Manoeuvres and Airway Adjuncts

• Jaw thrust and head-tilt chin-lift: relieve tongue-base obstruction; jaw thrust preferred if cervical spine injury possible
• Nasopharyngeal airway (NPA): tolerated by semi-conscious patients; size 6-7 for adults; lubricate well; contraindicated with suspected base-of-skull fracture
• Oropharyngeal airway (Guedel): only for the unconscious patient; stimulates gag reflex if any cough/swallow reflex present
• High-flow nasal oxygen (HFNO): provides apnoeic oxygenation during intubation attempts; can extend safe apnoea time significantly by maintaining oxygenation via physiological oxygen reservoir

2. Bag-Mask Ventilation

• Two-person technique preferred in the obstructed airway
• May be impossible if there is fixed structural obstruction; do not persist with ineffective BMV when escalation is needed

3. Supraglottic Airway Devices

• Second-generation SGAs (LMA ProSeal, LMA Supreme, iGel) provide gastric port and better seal
• Limit: cannot bypass glottic or subglottic obstruction; may worsen trauma in laryngeal fracture
• Can serve as conduit for fibreoptic intubation if glottis is accessible via the SGA

4. Endotracheal Intubation

Standard RSI: appropriate when the clinician is confident the airway can be secured rapidly and BMV is possible as a rescue

Awake fibreoptic intubation (AFOI): the technique of choice for the predicted difficult or obstructed airway when time permits

• Topicalise nasopharynx and larynx with 4% lignocaine (total dose $\leq 4\,\text{mg/kg}$; risk of toxicity in spray-as-you-go technique)
• Nebulised lignocaine 4% pre-procedure reduces discomfort
• Administer low-dose sedation with caution: propofol, ketamine or dexmedetomidine at sub-anaesthetic doses; maintain spontaneous ventilation throughout
• Pass scope nasally in most cases; oral approach via Ovassapian or Berman airway for nasal contraindications
• Advance endotracheal tube (size 7.0 adult female, 8.0 adult male) over scope under direct vision
• Critical principle: always confirm position by direct visualisation of carina and bilateral breath sounds before administering induction agents

Video laryngoscopy: improved glottic view compared to direct laryngoscopy in most anatomical variants; does not replace AFOI in progressive obstruction with distorted supraglottic anatomy, but is a useful adjunct or rescue device

5. The Surgical Airway

Indications:

• Cannot intubate, cannot oxygenate (CICO) scenario
• Complete upper airway obstruction not amenable to other techniques
• Anticipated inability to intubate before induction (relative indication for awake tracheostomy)
• Post-laryngectomy patients: these patients have a permanent stoma and no nasopharyngeal airway; bag-mask ventilation to the face is futile; ventilate via the stoma

Surgical Airway Techniques

Emergency Cricothyroidotomy

The cricothyroid membrane (CTM) is the primary landmark: a fibromuscular membrane between the inferior border of the thyroid cartilage and the superior border of the cricoid cartilage. It is approximately 9 mm in height and 30 mm wide in adults, and lies in the midline, accessible through only a thin layer of subcutaneous tissue and skin.

Surgical anatomy:

• Structure at risk: superior cricothyroid arteries run along the superior margin of the membrane bilaterally; incise low on the membrane to avoid these
• The CTM is avascular centrally; this is the safe zone
• Pitfall: in the obese or post-irradiated neck, landmarks may be impalpable; use ultrasound if available and time permits

Scalpel-Finger-Bougie (Standard Emergency Technique)

1. Position the patient supine with neck extended if possible
2. Identify the CTM by palpation: locate the laryngeal prominence, slide inferiorly to the first soft depression (CTM), then the firm ring of the cricoid below
3. Stabilise the larynx with the non-dominant hand using the "laryngeal handshake" (thumb and middle finger lateral, index finger palpating the membrane)
4. Make a horizontal stab incision through skin and membrane, approximately 1.5-2 cm wide
5. Hook the inferior flap of the CTM with the index finger to maintain access
6. Pass a bougie through the incision, directing it inferiorly (angled toward the carina)
7. Railroad a cuffed tube (6.0 ID ETT or dedicated cricothyroidotomy tube) over the bougie
8. Inflate cuff, confirm ventilation by capnography and bilateral auscultation
9. Secure the tube; plan conversion to formal tracheostomy within 24-72 hours

Needle Cricothyroidotomy

• Indication: extremely limited role in adults; primarily a paediatric temporising measure; provides inadequate minute ventilation in adults without jet ventilation
• Technique: 14 G cannula through CTM at 45° caudally; connect to Manujet or Sanders injector (jet ventilation at 1-4 bar); expiration must be passive and unobstructed or risk of fatal barotrauma and surgical emphysema
• Time-limited: effective oxygenation for approximately 30-45 minutes maximum before $\text{CO}_2$ accumulation becomes critical
• Proceed immediately to definitive surgical airway

Awake Tracheostomy Under Local Anaesthesia

Indications:

• Anticipated CICO where anatomy is accessible
• Malignancy with glottic obstruction (e.g. T4 laryngeal carcinoma, bilateral vocal fold palsy from malignant invasion)
• Compromised anatomy precluding safe intubation (severe laryngotracheal stenosis, post-irradiation changes, failed prior AFOI)
• Ludwig's angina or deep neck space infection with airway compromise

Technique:

1. Titrate sedation carefully; maintain spontaneous ventilation throughout
2. Infiltrate subcutaneous tissue with 1% lignocaine + 1:100,000 adrenaline along the planned incision
3. Transverse or vertical skin incision at the level of the 2nd-4th tracheal rings (avoid the 1st ring to prevent subglottic stenosis)
4. Divide strap muscles in midline raphe; identify isthmus and retract or divide
5. Apply stay sutures lateral to the planned tracheal window before entering the trachea; these are critical rescue sutures if the tube is inadvertently dislodged in the early postoperative period
6. Tracheal window: Bjork flap (inferiorly based) or horizontal incision between rings; enter at the lower half of the 2nd or upper 3rd ring
7. Insert cuffed tracheostomy tube (Shiley size 8 for most adults); inflate cuff; confirm with capnography

Emergency Surgical Tracheostomy

• Performed under local anaesthesia in the conscious patient with imminent or complete obstruction
• Same technique as above but performed more rapidly, with assistance of a second surgeon to control haemostasis while the first enters the trachea
• Avoid high tracheostomy (through or above the cricoid): risk of subglottic stenosis
• Avoid low tracheostomy (below the 4th ring): risk of innominate artery erosion and haemorrhage

Post-Airway Securing: Immediate Priorities

• Confirm position: end-tidal $\text{CO}_2$ waveform capnography is the gold standard; SpO₂, bilateral breath sounds and chest rise are supplementary
• Maintain cuff pressure between 20-30 cmH₂O; excess cuff pressure ($> 30\,\text{cmH}_2\text{O}$) risks tracheal mucosal ischaemia and late stenosis
• ICU transfer: patients with secured surgical airways require monitoring for haemorrhage, tube displacement, and pneumothorax
• Definitive management of the underlying cause (surgical drainage, oncological planning, immunotherapy for HAE, etc.) should be initiated once the airway is stable
• MDT communication: clearly document the airway difficulty, technique used, tube size and position for all subsequent treating teams

Special Scenarios

The Post-Laryngectomy Patient

• Has a permanent end-tracheostoma; the pharynx and trachea are completely separated
• No connection between the oral/nasal airway and the trachea: bag-mask ventilation to the face is ineffective and dangerous (causes gastric distension only)
• Ventilate via the stoma; use a standard ETT (6.0) or tracheostomy tube inserted into the stoma
• Stoma CPR: place resuscitation mask directly over the stoma for rescue breathing

Bilateral Vocal Fold Immobility

• Most commonly post-thyroidectomy (bilateral RLN injury) or from bilateral RLN invasion by malignancy
• Both folds lie in paramedian position; adequate for phonation but inadequate airway at rest or on exertion
• Management: immediate reintubation if acute (post-extubation); subsequent options include endoscopic posterior cordotomy, arytenoidectomy or laryngeal pacemaker; long-term tracheostomy if unresponsive to lateralisation procedures

Post-Thyroidectomy Haematoma

• Classic presentation: expanding neck haematoma within 6-24 hours post-thyroidectomy; patient unable to lie flat, stridor developing
• Do not wait for formal theatre: open wound at the bedside immediately (remove clips or sutures down to the strap muscles); this decompresses the superficial haematoma
• Deep haematoma below the strap muscles may persist; secure airway (intubation preferred if glottis visible) then return to theatre for formal haemostasis
• Early intubation is preferable to surgical airway in this scenario if the glottis is accessible

Angioedema

• Allergic (IgE-mediated): rapid onset, urticarial rash, responds to adrenaline; most secure airway early as progression can be rapid
• Hereditary angioedema (HAE): C1-esterase inhibitor deficiency; no urticaria; worsens with adrenaline and antihistamines; treat with specific agents (C1-INH concentrate, icatibant); high rate of airway involvement requiring intubation or surgical airway

Complications of Surgical Airway

Team, Communication and System Considerations

• The CICO scenario must be rehearsed as a team, not improvised: roles for airway manager, assistant, circulating nurse and drug administrator must be pre-assigned
• Cognitive aids (airway emergency algorithms, drug dosing cards) reduce error under physiological stress; having these displayed or immediately accessible in theatres and emergency departments is standard practice in Australian and New Zealand hospitals
• Handover after airway securing must be explicit: technique used, tube type and size, depth at teeth/stoma, cuff pressure, difficulty encountered and plan for subsequent management
• Consent: in a true airway emergency, implied consent operates; where time permits (e.g. planned awake tracheostomy for malignancy), full informed consent including the risks of haemorrhage, pneumothorax, tracheal stenosis, tube displacement and the possibility of tracheostomy dependence must be obtained and documented