page_title: Pneumatosis
section_title: Lungs
hierarchical_section_title: Pneumatosis / By location / Lungs
caption_attribution_description: English: Bullus emphysema as seem on CT
context_page_description: Pneumatosis, also known as emphysema, is the abnormal presence of air or other gas within tissues.
  In the lungs, emphysema involves enlargement of the distal airspaces, and is a major feature of chronic obstructive pulmonary disease.
  Pneumoperitoneum is air or gas in the abdominal cavity, and is most commonly caused by a perforated abdominal organ. Pneumatosis is also a frequent result of surgery. The term is from pneumat- + -osis.
  Pneumarthrosis is the presence of air in a joint, and is rarely a serious sign.
context_section_description: Pulmonary emphysema, more usually called emphysema, is characterised by air-filled cavities or spaces, (pneumatoses) in the lung, that can vary in size and may be very large. The spaces are caused by the breakdown of the walls of the alveoli and they replace the spongy lung parenchyma. This reduces the total alveolar surface available for gas exchange leading to a reduction in oxygen supply for the blood. Emphysema usually affects the middle aged or older population. This is because the disease takes time to develop with the effects of smoking, and other risk factors. Alpha-1 antitrypsin deficiency is a genetic risk factor that may lead to the condition presenting earlier.
  It is a typical feature of chronic obstructive pulmonary disease (COPD), a type of obstructive lung disease characterized by long-term breathing problems and poor airflow. Even without COPD, the finding of pulmonary emphysema on a CT lung scan confers a higher mortality in tobacco smokers. In 2016 in the United States there were 6,977 deaths from emphysema – 2.2 per 100,000 of the population. A study on the effects of tobacco and cannabis smoking showed that a possibly cumulative toxic effect could be a risk factor for developing emphysema, and spontaneous pneumothorax. 
  There is an association between emphysema and osteoporosis.
  There are three subtypes of pulmonary emphysema – centrilobular or centriacinar, panlobular or panacinar, and paraseptal or distal acinar emphysema, related to the anatomy of the lobules of the lung. These are not associated with fibrosis (scarring). A fourth type known as irregular emphysema involves the acinus irregularly and is associated with fibrosis. Though the subtypes can be seen on imaging they are not well-defined clinically.
  Only the first two types of emphysema – centrilobular, and panlobular are associated with significant airflow obstruction, with that of centrilobular emphysema around 20 times more common than panlobular.
caption: CT scan of bullous emphysema.
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