Consider pneumothorax (Table 64.1) in any patient with:

• Sudden breathlessness or chest pain, particularly in young, otherwise fit adults or following invasive procedures, for example subclavian vein cannulation, lung biopsy, chest aspiration.
• Exacerbation of chronic obstructive pulmonary disease (or rarely asthma): pneumothorax may be painless and contribute to respiratory failure.
• Hypoxia, an increase in inflation pressure or unexplained hypotension in the mechanically ventilated patient: asymmetry of chest expansion is a useful clue.

Management of suspected pneumothorax is summarized in Figure 64.1.