When fresh air containing oxygen enters the alveoli, the oxygen is able to move into the capillaries to be carried back to the left side of the heart. Normally, the alveoli remain open all the time. Problems can occur that can make the alveoli close.
Fluid edema around alveoli, secretions in the airway or fluid or air in the sac around the lung can put pressure on the alveoli and make them collapse. Because oxygen cannot enter alveoli that are collapsed, alveolar collapse causes the concentration of oxygen in the blood to fall. Airless areas of lung are called atelectic areas. Secretions phlegm in the airway can cause segments of the lung to collapse and become atelectic.
The more alveoli that are closed, the less gas exchange occurs. Accordingly, atelectasis can decrease the level of oxygen in the blood.
The body compensates for a small amount of atelectasis by closing off constricting the blood vessels in the affected area. This constriction redirects blood flow to alveoli that are open so that gas exchange can continue. Blockage of one of the tubes bronchi that branch off from the trachea windpipe and lead to the lung tissue. The blockage may be caused by something inside the bronchus, such as a plug of mucus, a tumor, or an inhaled foreign object such as a pill, a piece of food, or a toy.
Alternatively, the bronchus may be blocked by something pressing from the outside, such as a tumor or an enlarged lymph node. Blockage from the outside can also occur if the pleural space the space outside of the lung but inside of the chest contains a large amount of fluid pleural effusion Pleural Effusion Pleural effusion is the abnormal accumulation of fluid in the pleural space the area between the two layers of the thin membrane that covers the lungs.
Fluid can accumulate in the pleural When a bronchus or a smaller airway bronchiole becomes blocked, the air in the alveoli beyond the blockage is absorbed into the bloodstream, causing the alveoli to shrink and collapse. The area of collapsed lung may become infected because bacteria and white blood cells can build up behind to the inside of the blockage. Infection is particularly likely if atelectasis persists for several days or more.
If atelectasis persists for months, the lung may not easily re-expand. Large doses of opioids or sedatives can decrease deep breathing. Atelectasis is particularly common after chest or abdominal surgery because the effects of receiving general anesthesia may be added to the pain of deep breathing, so people take only shallow breaths. Chest or abdominal pain due to other causes for example, injury or pneumonia Overview of Pneumonia Pneumonia is an infection of the small air sacs of the lungs alveoli and the tissues around them.
Pneumonia is one of the most common causes of death worldwide. Often, pneumonia is the final Certain neurologic conditions, immobility, and chest deformities can limit chest movement and thus decrease deep breathing, as can abdominal swelling. People who are very overweight or obese are also at greater risk of developing atelectasis. People who smoke can decrease their risk of atelectasis after surgery by stopping smoking, ideally 6 to 8 weeks before the surgery.
Atelectasis itself does not cause any symptoms except sometimes shortness of breath. The presence and severity of shortness of breath depend on how rapidly atelectasis develops and how much of the lung is affected.
If atelectasis involves a limited portion of the lung or develops slowly, symptoms may be mild or not even noticed. If a large number of alveoli are affected, particularly if atelectasis occurs rapidly, shortness of breath may be severe.
The heart rate and breathing rate may increase, and sometimes the person may look bluish a condition called cyanosis Cyanosis Cyanosis is a bluish discoloration of the skin resulting from an inadequate amount of oxygen in the blood.
Cyanosis occurs when oxygen-depleted deoxygenated blood, which is bluish rather than Symptoms may also reflect the disorder that caused atelectasis for example, chest pain due to an injury or a disorder that results from atelectasis for example, chest pain with deep breathing, due to pneumonia Overview of Pneumonia Pneumonia is an infection of the small air sacs of the lungs alveoli and the tissues around them.
Show references Ferri FF. In: Ferri's Clinical Advisor Philadelphia, Pa. Accessed July 10, Conde MV, et al. Overview of the management of postoperative pulmonary complications. Accessed July 20, Goldman L, et al. Bronchiectasis, atelectasis, cysts, and localized lung disorders. In: Goldman-Cecil Medicine. Accessed July 23, Smetana GW, et al. Strategies to reduce postoperative pulmonary complications. Accessed August 20, Bope ET, et al.
In: Conn's Current Therapy Restrepo RD, et al. Current challenges in the recognition, prevention and treatment of perioperative pulmonary atelectasis. Expert Review of Respiratory Medicine.
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