Ambulatory management of primary spontaneous pneumothorax: the good is (not always) the enemy of the better (evidence).

Pneumothorax is defined as the presence of air in the pleural cavity. A pneumothorax might occur spontaneously in patients without underlying lung disease (primary spontaneous pneumothorax (PSP)) or in patients with an underlying lung disease (secondary spontaneous pneumothorax), most commonly chronic obstructive pulmonary disease. The underlying cause of spontaneous pneumothorax is likely to be the rupture of ‘‘emphysema-like changes’’ (small bullae or blebs) on the pleural surface, which allows air from the lung into the pleural space. Smoking, male sex and height are the major risk factors for the development of a PSP. There is evidence of a pleural inflammatory reaction in patients with PSP, involving an increase in eosinophils and neutrophils as well as elevated inflammatory cytokines compared with blood levels [1].