**1. Introduction**

Spontaneous pneumothorax (SP) is a type of collection of air in the pleural cavity that develops in the absence of trauma or iatrogenic cause [1, 2]. It is further classified as primary and secondary SP (PSP/SSP). While PSP affects patients with no clinically apparent lung disorders but small subpleural blebs/bullae, SSP involves an underlying pulmonary disease, which most often is chronic obstructive pulmonary disease (COPD) [2]. Spontaneous pneumothorax is a significant health burden, with annual incidences of 18–28 and 1.2–6 cases per 100,000 men and women, respectively [3]. The annual incidences of PSP among men and women are 7.4–18 (age-adjusted incidence) and 1.2–6 cases per 100,000 population, respectively; the annual incidences of SSP are similar, approximately 6.3 and 2 cases per 100,000 men and women, respectively [3].

Patients usually present with chest pain or breathlessness or both. Associated haemodynamic instability is an indication of a tension pneumothorax. The pathophysiology of PSP is a ruptured bleb or bullae which is usually located at the apex of the upper lobe or less frequently in the apical segment of the lower lobe. There is no known predisposing factor for its rupture and the resultant pneumothorax. SSP is caused more frequently by rupture of bullae in an underlying diseased lung, most commonly due to COPD/emphysema. It carries a significantly higher risk than PSP with mortality approaching 15% mainly due to associated patient comorbidities and low pulmonary reserve [4]. These differences between PSP and SSP are appreciated in guideline recommendations for management of spontaneous pneumothorax.
