Atelectasis

Atelectasis is a partial or complete collapse of all or part of the lung. It arises when tiny air sacs within the lung called alveoli become deflated or, in some cases, filled with alveolar fluid. This means that the affected lung is unable to take in enough air for oxygen for organs and tissues. Atelectasis most commonly occurs as a complication following surgery. It can be tied to problems like cystic fibrosis, fluid accumulation in the lungs, lung tumors, chest injuries, and general respiratory weakness. Atelectasis can also be caused by inhalation of a foreign object. Symptoms of atelectasis may include difficulty breathing; rapid, shallow breathing; wheezing; and coughing. While atelectasis is usually not life-threatening, it often needs to be treated quickly or it become deadly. Treatment for atelectasis varies depending on the cause of the collapse and the severity of the patient’s condition. It can range from simple chest physiotherapy to surgical intervention.

Background

Along with the brain and heart, the lungs are the most critical organs in the human body. Most importantly, they allow for the intake of oxygen, which is a vital element that the body depends on for survival. The respiratory system is made up of five main parts: the upper airways, the trachea, the bronchi and bronchioles, and the alveoli. When air is inhaled through the nose or mouth, it travels down the back of the throat, through the voice box, and into the trachea, which is also commonly referred to as the windpipe. The trachea houses two separate air passages known as bronchial tubes. One of these tubes leads to the left lung and the other leads to the right lung. To operate efficiently, these airways must be open and free of inflammation or abnormal accumulations of mucus.

The lungs themselves are actually not identical. The right lung is a little larger than the left lung and consists of three distinct sections, or lobes. The left lung has only two lobes. As the bronchial tubes enter each lung, they further divide into smaller air passages. The larger of these passages are called bronchi, while the smaller are called bronchioles. The bronchioles ultimately end in alveoli, which are tiny air sacs that transfer oxygen into the blood.

Under normal circumstances, the respiratory system has a number of built-in defenses to help prevent harmful substances from entering the lungs. The nose has small hairs that together function as an air-filtering system and keep large particles out of the airways. The trachea and bronchial tubes produce mucus that keeps the airways moist and helps intercept dust, bacteria, and other potentially harmful substances. Tiny hairs in the trachea called cilia help keep the airways clean. While these defenses are normally effective, they are not always able to keep harmful substances out of the lungs. If a harmful substance or foreign object does reach the lungs—or if there is simply too much mucus in the airways—the lungs’ ability to oxygenate the blood may be compromised, and serious issues like atelectasis may result.

Overview

The alveoli play a critical role in the exchange of oxygen for carbon dioxide, which is a gaseous waste product that is removed from the body through exhalation. This process requires the alveoli to fill with air. When the alveoli are unable to fill with air for one reason or another, the resulting condition is referred to as atelectasis. Atelectasis can occur in a large or small portion of the lung. Its extent typically depends on the underlying cause. It is also important to note that atelectasis is a different condition from what is usually referred to as a “collapsed lung.” That condition, called pneumothorax, occurs when air gets stuck in the space between the exterior of the lung and the inner chest wall. However, pneumothorax can lead to atelectasis if the lung collapses enough to cause the alveoli to deflate.

The symptoms of atelectasis can vary depending on how much of the lung is affected and how quickly the condition develops. Mild atelectasis affecting only a small portion of the lung may not produce any noticeable symptoms at all. More pronounced symptoms are likely to be present when a larger part of the lung is affected and the patient’s blood oxygen level is lower. The most common signs of atelectasis are difficulty breathing, sharp chest pains, rapid breathing, elevated heart rate, and blue-colored skin, lips, fingernails, or toenails. In some cases, atelectasis may also be accompanied by symptoms of pneumonia, such as a productive cough and fever.

There are many possible causes of atelectasis. Individual cases are categorized as either obstructive or non-obstructive depending on the exact cause. Obstructive atelectasis occurs when a blockage forms in the airways and air is unable to reach the alveoli. Blockages of this sort can be caused by the inhalation of a foreign object, a buildup of mucus, the growth of a tumor within an airway, or the presence of a lung tumor that presses on the airway. Non-obstructive atelectasis has more varied causes. It often occurs following surgical procedures involving the use of anesthesia, pain medications, and sedatives. Taken together, these substances can lead to shallow breathing and may suppress coughing. This, in turn, can cause the alveoli to collapse. Non-obstructive atelectasis can also be caused by pneumothorax, lung scarring, chest tumors, or a lack of surfactant, which is a substance in the lungs that helps the alveoli to stay open.

The treatment of atelectasis varies depending on the cause and severity of individual cases. Most cases of atelectasis can be treated non-surgically. One of the most common non-surgical treatments for atelectasis is chest physiotherapy, which involves moving the body into different positions and using tapping motions or vibrations to loosen and drain mucus. Other non-surgical treatments include the removal of a foreign object or mucus plug via bronchoscopy, drainage, and simple breathing exercises. Pharmaceutical treatment may also be prescribed. In some severe cases of atelectasis, surgical intervention may be required. This usually means surgically removing part of a lobe in the affected lung.

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