Accumulation of air in the pleural space.
Primary spontaneous pneumothoraces occur in young people without known respiratory illnesses. Patients with pre-existing pulmonary diseases may develop secondary spontaneous pneumothoraces.
A tension pneumothorax is a medical emergency that requires immediate intervention to decompress the involved hemithorax.
Patients with pneumothoraces typically complain of dyspnoea and chest pain. In tension pneumothorax, patients are distressed with rapid laboured respirations, cyanosis, profuse diaphoresis, and tachycardia.
First-line treatment of pneumothoraces includes observation with supplemental oxygen therapy, percutaneous aspiration of the air in the pleural space, chest-tube thoracostomy, and in some cases video-assisted thoracoscopy or thoracostomy.
Patients who suffer spontaneous pneumothoraces are at risk for recurrence. Pleurodesis (either by mechanical abrasion or by chemical irritation of pleural surfaces) is used to limit the likelihood of recurrence.
Pneumothorax occurs when air gains access to, and accumulates in, the pleural space. 
Associate Professor of Medicine and Oncology
Clinical Director, Division of Pulmonary and Critical Care
Director, Interventional Pulmonology Research Core
Johns Hopkins Medical Institutions
LY has received research grants and consulting fees from Olympus, Inc, the manufacturer of the Spiration intrabronchial valve.
Assistant Professor of Medicine
Director, Interventional Pulmonology
Carolina Center for Pleural Disease
University of North Carolina
JA declares that he has no competing interests.
Dr Lonny Yarmus and Dr Jason Akulian would like to gratefully acknowledge Dr Ryland P. Byrd Jr, Dr Thomas M. Roy, and Dr Anita Alwani, previous contributors to this topic.
Professor and Chief Executive Officer of Respiratory Division
Interventional Endoscopy Clinic
University Hospital Brussels
MN declares that he has no competing interests.
Professor of Medicine
Division of Pulmonary Critical Care, Allergy and Sleep Medicine
Medical University of South Carolina
SAS declares that he has no competing interests.
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