Table 2.

Preoperative investigations.

Investigation	Rationale	When to consider
Full blood count	Assess for anaemia. Important determinant of oxygen-carrying capacity.	All patients.
Biochemistry	Assessment of thyroid function and investigation for paraneoplastic syndromes may be important.	Thyroid function biochemistry important if underlying thyroid pathology is the indication for airway stenting. Useful to exclude or confirm a paraneoplastic syndrome in patients with underlying malignant disease.
ECG	Allows baseline comparison in the event of signs of myocardial ischaemia or infarction during the perioperative period.	All patients.
Chest X-ray	Allows assessment of any pulmonary collapse or pneumonia and any mediastinal shift.	All patients.
Transthoracic echocardiogram	Allows assessment of baseline cardiac function.	Patients with risk factors for or known cardiac disease
Chest CT with three-dimensional reconstruction	Allows detailed assessment of airway anatomy. Areas of stenosis may be identified. May assist in airway management planning.	All patients.
Pulmonary function tests	Permits assessment of the level of obstruction and whether the obstruction is fixed or dynamic. Also allows assessment of underlying pulmonary parenchymal disease.	All patients.