FRCA Notes

Mediastinal Masses

Resources

  • The presence of a mediastinal mass makes anaesthesia challenging and higher risk
  • Methods to circumvent the need for a GA should be explored e.g. biopsy of peripheral lymph node, bone marrow biopsy or sampling of pleural effusion may be preferable

Malignant Infectious Autoimmune/inflammatory Drug-induced lymphadenopathy
Lymphoma (Hodgkin's or NHL) TB Sarcoidosis Allopurinol
Thymoma HIV Rheumatoid arthritis Penicillins
CLL EBV (infectious mononucleosis) SLE Atenolol
ALL Toxoplasmosis Silicosis


Airway

  • Stridor due to turbulent flow through a narrowed airway ± airway compromise
    • May be laryngeal (inspiratory) stridor indicating obstruction above the glottis
    • May be tracheobronchial (expiratory) stridor indicating intrathoracic airway obstruction
    • May be biphasic stridor, indicating critical obstruction or obstruction between glottis and subglottis
  • Difficult airway due to tracheal obstruction/narrowing/compression
  • Propensity for airway oedema and haemorrhage

Cardiovascular i.e. SVCO

  • Vascular impingement with SVCO leading to haemodynamic instability
  • The thin-walled SVC is readily compressed, leading to obstructed venous drainage from the upper half of the body
  • Typically occurs due to extrinsic compression by tumours, but can be due to thrombus within the vessel
  • Patients may have:
    • Facial swelling/fullness
    • Nasal stuffiness
    • Orthopnoea
    • Stridor
    • Pemberton's sign - facial plethora & respiratory distress when both arms are elevated due to thoracic inlet obstruction

Other organ systems

  • There may be recurrent larygeal nerve palsy from compression
  • Dysphagia can arise leading to an increased aspiration risk

Effects of anaesthesia

  • Orthopnoea may require induction in sitting position
  • Loss of airway and respiratory muscle tone at induction can lead to complete, potentially fatal airway obstruction
  • May be exacerbated in children due to greater compressibility of the paediatric airway and surrounding structures

Perioperative management of the patient undergoing surgery for a mediastinal mass


History and examination

  • Standard anaesthetic pre-assessment, with focus on:
    • Dyspnoea including severity, factors exacerbating it inc. positional changes
    • Positional cough
    • Functional capacity
    • Added sounds i.e. stridor and their timing in the respiratory cycle

Investigations

  • Bloods: FBC, U&E, LFT, clotting
  • CXR
  • ECG
  • TTE - ? Pericardial effusion

  • Airway assessment with:
    • CT neck and chest
    • Nasendoscopy
    • Spirometry i.e. flow-volume loops

Optimisation

  • These patients should pass through an MDT including oncologists (if relevant), surgons, anaesthetists and radiologists
  • Steroid or chest radiotherapy can be employed to reduce tumour size, improve symptoms, reduce mass effect and reduce risks of anaesthesia/surgery
    • Steroids may be contra-indicated if they risk obscuring the histological diagnosis
  • Aim for surgery to take place within 24hrs of finishing steroid treatment

  • In general these patients should have surgery in a specialist centre under the auspices of a consultant surgeon and consultant anaesthetist

Monitoring

  • AAGBI as standard
  • IV access in the lower limb in case of obstructed venous return via the upper limbs i.e. SVCO
  • Arterial line
  • Femoral access e.g. for rescue strategy such as CPB or ECMO

Choice of technique

Regional anaesthesia General anaesthesia
If symptomatic with definitive radiographic airway obstruction If RA refused
If tracheal cross sectional area <50% predicted If RA unfeasible e.g. paediatric
If PEFR <50% predicted
→ cervical plexus block +
ketamine/dexmedetomidine sedation		 → aim for SV on an LMA

General anaesthesia

  • Although GA should be avoided if possible, technique includes:
    • Induction in semi-Fowler's (sitting 15-45°) position
    • Inhalational or titrated IV (ketamine) induction
    • Aim for SV on an LMA; avoid PPV as it can induce hypotension & increase intrathoracic tracheal compression
    • Avoid NMBA
    • TIVA or volatile maintenance
    • Avoid coughing as positive pleural pressure may cause complete airway obstruction

CICO scenario

  • Unlike traditional CICO, FONA may be impossible or futile if the obstruction is inferiorly situated
  • Instead one should:
    • Change position to reduce mechanical effect of tumour e.g. sit up, lateral, prone
    • Avoid PPV
    • Give high-dose steroids

  • Options for oxygenation include:
    • Rigid bronchoscopy
    • OLV
    • Jet ventilation
    • Extra-corporeal oxygenation e.g. CPB, ECMO

  • Post-operative airway obstruction due to oedema, haemorrhage or tracheomalacia can occur
  • Ensure dexamethasone has been given
  • Perform a cuff leak test
  • Have adrenaline nebulisers to hand
  • Extubate over an airway exchange catheter
  • May require admission to ICU I&V and extubation at later date following reduction in swelling