Anterior mediastinal mass

 

Summary:

·         Complex surgery

·         Variable risk of airway or circulatory disaster

·         Needs pre-op investigation and planning

 

Origin:

Mediastinum

·      Lymph node

·      Thymus

·      Germ cell

Lung

·      Bronchogenic carcinoma

Neck

·      Thyroid

Elsewhere

·      Metastasis

 

The four M’s:

Mass

·      Mass itself- > compress vital structures (see below)

·      Associated effusions (e.g. pleural, pericardial)

Metastases

·      CNS

·      Viscera

·      Musculoskeletal

Metabolic

·      Native: e.g. T4 -> thyrotoxicosis

·      Paraneoplastic: e.g. PTHrP -> hypercalcaemia

Medication

·      Lymphoma -> glucocorticoid

·      Cancer -> chemotherapy -> cardiotoxicity, lung toxicity

·      Thyroid -> carbimazole, PTU

Mood

·      Anxiety

·      Grief

 

Mass effects:

Trachea and bronchi squashed

-> Failed intubation -> CICO

-> Dynamic hyperinflation -> obstructive shock

·      Hx: dyspnoea, intolerance of exertion

·      Ex: hoarse voice, stridor

·      Ix: CT

·      Prevention: spont vent gradual TCI, AFOI

·      Treatment: lateral or prone, rigid bronch + jet, bougie

Heart and great vessels squashed

-> Arrest at induction

·      Hx/Ex: supine dyspnoea and pre-syncope

·      Ix: CT, TTE

·      Prevention: spont vent gradual TCI, elective EMCO

·      Treatment: lateral or prone, ALS (not crash onto ECMO)

SVC squashed

-> Airway oedema -> CICO

-> ↑ICP -> ischaemia

-> Ineffective upper limb veins

·      Hx/Ex: Pemberton’s sign

·      Ix: CT, TTE

·      Mitigation: lower limb PIVC

 

Pre-op:

Investigation

Imaging:

·      CT chest (? size ? compression ? airway calibre)

·      CT pan-scan (? mets)

·      TTE (? cardiac chamber compression)

·      Spirometry (? fixed inspiratory and expiratory airflow obstruction)f

Blood tests:

·      BGHO

·      Hb, platelets, baseline coag

Treatment

·      Shrink the mass (e.g. glucocorticoid, chemo, rad, drainage)

·      Treat its effects (e.g. hormone antagonist)

·      Widen the airway (i.e. tracheal stent)

·      Optimise comorbidities

Risk stratification

Symptoms + CT chest:

·      CVS collapse risk: size + symptoms

·      Airway disaster risk: narrowing (beware if >50%)

Planning

·      MDM: anaes + CTS + oncology

·      Discuss proceed vs abandon vs alternatives

·      If proceeding, discuss both airway + circulation problems

 

Pre-induction:

Personnel

·      Anaesthesia nurse

·      Second anaesthetist (preferably cardiac)

·      Technicians ready to flip the patient

·      ± Thoracics with rigid bronchoscope

·      ± Cardiac scrubbed for sternotomy

·      ± Cardiac scrubbed for ECMO

A&B equipment

·      Usual equipment

·      Video laryngoscope

·      Flexible bronchoscope

·      Microlaryngoscopy ETTs

C equipment

·      Pumpset with fluid warmer

·      Large PIVC in UL and LL

·      A-line in LL

·      CVC in LL

·      Consider ECMO: must be pre-induction if at all

Monitoring

·      Standard

·      A-line

·      IDC

 

Induction:

Low risk

·      Normal induction

High airway risk

·      ±Spont vent gradual TCI

·      ±AFOI pre-induction

High circulation risk

·      ±Spont vent gradual TCI

·      ±ECMO pre-induction

Unknown risk

·      Don’t know. Shared decision-making.