FRCA Notes

Inhaled Foreign Body

This topic straddles the paediatric, airway and ENT portions of the curriculum, which (in summary) asks us to be able to describe the principles of anaesthetic management in cases of inhaled foreign body.

The September 2022 CRQ on this topic (60% pass rate) saw candidates lose marks for not knowing "the specific complications when anaesthetising this type of case".

Resources

  • Inhaled foreign bodies are a common surgical emergency in young children
  • They pose particular problems pertaining to anaesthetic management, including:
    • Shared airway surgery
    • Difficulty maintaining airway patency
    • Difficulty maintaining anaesthesia during a very stimulating procedure
    • Need to prevent ± manage post-operative airway complications
  • Clinical features are mostly respiratory (see table below) although generic features such as distress/irritability, tachycardia and sweating may also be present
Clinical features of respiratory distress
Wheeze | grunting | stridor
Tracheal tug
Nasal flaring
Intercostal and subcostal recession
Use of accessory muscles and/or tripod positioning
See-saw pattern (paradoxical abdominal breathing)
Cyanosis (peripheral or central)
Reduced air entry on affected side


Perioperative management of the child undergoing removal of an inhlaed foreign body


  • Minimising anxiety whilst building rapport is vital
  • Paediatric anaesthetic history and assessment for features of respiratory distress as above
  • Avoid excessive intervention which could exacerbate respiratory distress

Chest X-ray

  • The majority of inhaled foreign material is organic and therefore not demonstrable on CXR
  • As such, the absence of radiographic abnormalities does not exclude the diagnosis of inhaled foreign body
  • If present, features on CXR could include:
    • Aspirated radio-opaque object
    • Consolidation or collapse
    • Mediastinal shift
    • Hyperinflation / gas trapping
    • Pneumothorax

Induction

  • It is preferable to keep the child spontaneously ventilating and avoid PPV, as the latter risks causing
    • Distal migration of the foreign body
    • A ball-valve effect leading to distal gas trapping
  • As such gas induction with sevoflurane is typically used, though IV induction may be appropriate (e.g. carefully titrated fentanyl + propofol)
  • Both techniques have their merits and demerits:
Gas induction + sponaneously ventilating IV induction + PPV
Avoids need for awake cannulation ↓ aspiration risk
Allows pre-oxygenation ↓ coughing/movement
↓ risk of distal migration ↓ atelectasis
Lessens degree of gas trapping Optimal oxygenation/ventilation
Allows rapid assessment of ventilation post-removal Easier to manage IV maintenance therapy as ventilation controlled
Difficult to maintain depth of anaesthesia Necessitates awake cannulation (if not already)
V/Q and CV effects of depth of anaesthesia needed to obliterate airway reflexes Can cause distal migration
Risk of coughing/movement Unable to assess ventilation immediately post-retrieval
Risk of hypercapnoea from ↑ airway resistance once bronchoscope in situ Can increase distal gas trapping
Harder to manage IV maintenance therapy as need to ensure remains SV

Maintenance

  • Dexamethasone should be used
  • After induction, topical LA may be applied (max 4mg/kg for airway topicalisation) e.g. spray with a mucosal atomisation device to anaesthetise the airway and tolerate surgical intervention

  • Surgical management includes use of a rigid bronchoscope
  • Maintenance can be achieved by insufflating volatile agents through said bronchoscope, although this vents waste anaesthetic gases into the operating theatre environment

  • IV maintenance with propofol ± opioid is also an option, e.g.: propofol 250μg/kg/min ± remifentanil 0.2μg/kg/min
  • Regardless of technique, the aim is to maintain a deep plane of anaesthesia as coughing and bucking on the rigid bronchoscope risks trauma or indeed bronchial/tracheal perforation

Oxygenation

  • Maintaining oxygenation can be difficult
    • Oxygen can be insufflated via the surgical bronchoscope or laryngoscope
    • THRIVE may be an option
  • Capnography is often impossible but presence of an open airway, administration of oxygen and reasonable respiratory effort should be reassuring

  • Once the culprit foreign body has been removed, one's options include:
    • Spontaneous breathing with simple airway support until emergence
    • SAD insertion for convenience
    • I&V if there is airway swelling, trauma or ongoing obstruction
  • Patients should be closely monitored post-operatively as oedema may continue for 48hrs

  • Airway infection or abscess
  • Laryngeal oedema ± stridor
  • Pneumothorax or haemothorax
  • Respiratory failure & ongoing oxygen requirement