The most common cause is post-surgical<unk> , characterized by splinting, i.e. restricted breathing after abdominal surgery.<unk>  develops in 75–90% of people undergoing general anesthesia for a surgical procedure. Another common cause is pulmonary tuberculosis. Smokers and the elderly are also at an increased risk. Outside of this context,<unk>  implies some blockage of a bronchiole or bronchus, which can be within the airway (foreign body, mucus plug), from the wall (tumor, usually squamous cell carcinoma) or compressing from the outside (tumor, lymph node, tubercle). Another cause is poor surfactant spreading during inspiration, causing the surface tension to be at its highest which tends to collapse smaller alveoli.<unk>  may also occur during suction, as along with sputum, air is withdrawn from the lungs. There are several types of<unk>  according to their underlying mechanisms or the distribution of alveolar collapse; resorption, compression, microatelectasis and contraction<unk> . Relaxation<unk>  (also called passive<unk>  is when a pleural effusion or a pneumothorax disrupts the contact between the parietal and visceral pleurae. Risk factors associated with increased likelihood of the development of<unk>  include: type of surgery (thoracic, cardiopulmonary surgeries), use of muscle relaxation, obesity, high oxygen, the lower lung segments. Factors also associated with the development of<unk>  include: age, presence of chronic obstructive pulmonary disease (COPD) or asthma, and type of anesthetic. In the early 1950s, in UK aviation medicine, the condition "acceleration<unk> " was given the name "Hunter Lung" due to its prevalence in pilots of the transonic fighter jet, the Hawker Hunter, which used a 100% oxygen supply.
Atelectasis
Pleurisy
Emphysema
Lobar pneumonia
Pleural effusion
Pyelectasis
Hydrothorax
Atypical pneumonia