FRCA Notes

Maxillofacial Infections

Resources

  • Head and neck infections can present with life-threatening complications, such as:
    • Airway obstruction
    • Mediastinal spread
    • Cavernous sinus thrombosis
  • The majority aren't quite so moribund, but may still pose airway challenges for the anaesthetist
  • Odontogenic infections begin with decay and inflammation of the nerve chamber of the tooth: pulpitis
  • Most infections are polymicrobial, including Strep., Staph., and Bacteroides
  • Infection spreads to the bone, perforating bony cortex into the subperiosteal region
  • Infection then spreads in fascial planes into potential spaces within the head and neck:
  • Complications can ensue from local spread:
    • From the premaxillary region to the orbit → orbital cellulitis and cavernous sinus thrombosis
    • Parapharyngeal abscess → airway compromise/obstruction
    • Sub-masseteric inflammation → trismus
    • Mediastinitis
    • Pulmonary aspiration of pus

OMFS-space-2.jpg

  • Spread may also be haematogenous, causing distal complications such as bacteraemia, endocarditis, septic joints or thrombophlebitis

  • This much-feared life-threatening floor-of-mouth cellulitis accounts for (depending on your source) up to ~5% of maxillofacial infections
  • It is an aggressive, rapidly spreading, bilateral infection of the sub-mandibular ± sub-lingual spaces
  • Since the disease is rare and early symptoms often nebulous, diagnosis and treatment can be delayed with fatal consequences

    • Clinical features

  • It often arises due to an infected molar tooth
  • It causes a 'woody' cellulitis in the sub-mandibular space
  • A failure to protrude the tongue is indicative of sub-lingual space involvement, owing to the shape of the genioglossus muscles
  • There is rapid spread of infection via fascial planes
    • There is typically a lack of lymphadenopathy since the (often) polymicrobial infection spreads along fascial planes as opposed to the lymphatic system
  • Patients may well be septic

    • Life-threatening sequelae

  • Upper airway obstruction - due to posterior infective extension and tongue distension with posterior displacement
  • Descending necrotising mediastinitis - due to spread of infection to the mediastinum via contiguous fascial planes
    • Such spread is promoted by gravity and negative intrathoracic pressure

    Management

  • CT cervical area + chest is the imaging modality of choice, as it allows delineation of the area of involvement, highlights abscesses amenable to I&D and assesses for mediastinal spread
  • I&D ± debridement is required
  • Naturally such extensive swelling can cause airway-related issues; some brave souls (BJA, 2009) have avoided perioperative airway folly by performing I&D under superficial cervical plexus block

  • Appropriate assessment to:
    • Define extent of disease progression
    • Look for indicators of airway compromise
    • Anticipate difficulties in airway management
    • Elucidate significant comorbidities impacting on conduct of anaesthesia

Airway compromise

Clinical features Examination findings
Altered speech Reduced mandibular protrusion
Odynophagia Reduced mouth opening
Dental pain Loss of mandibular contours
Worsening swelling Reduced interdental distance
Trismus Lack of tongue protrusion - sublingual involvement
Dysphagia High mallampati score
Stridor Reduced neck extension
Drooling Impalpable or distorted neck anatomy

Investigations

  • Bloods including infective markers
  • ECG
  • Flexible nasendoscopy can be incredibly useful
  • May require CT or USS of their head and neck to facilitate surgical diagnosis, operative strategy and airway evaluation

  • Senior anaesthetic and surgical input is required

Anaesthetic technique

  • The choice of technique will be influenced by patient, anaesthetic and surgical factors, and can take many forms
    • E.g. a patient with limited mouth opening is unlikely to have increased mouth opening following induction, so ATI is indicated
  • Options include the gamut of airway strategies: conventional induction, RSI, inhalational induction, awake tracheal intubation etc.
  • Surgical tracheostomy is an option, though often difficult due to the involvement of the neck and pre-tracheal tissues
    • Incising through these tissues risks mediastinitis, which carries a significant mortality

Other considerations intra-operatively

  • There'll be difficult access to the airway; the operating table may need to be rotated 90 - 180° relative to the anaesthetic machine
  • Throat packs may be used to absorb pus, blood and secretions
  • IV dexamethasone is often required, including post-operatively
  • Antibiotics should be given according to local microbiological guidance
  • Analgesia is with simple analgesics, intra-oral LA and opioids; one may wish to be judicious with the latter if there is concern about airway compromise

  • The decision about extubation should be made on a patient-by-patient basis, involve surgical input and ideally follow the DAS Guidelines for the management of tracheal extubation (2012)
  • Some patients may develop worse swelling post-operatively, particularly those with Ludwig's angina or parapharyngeal involvement
  • The surgical team should be present during extubation, and a period of in-theatre observation might be sensible prior to transfer to recovery