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What Does Atelectasis Mean?
Atelectasis (sometimes spelled “atelectasia”) is the medical term used to describe the failure of an organ to expand normally, or its collapse from a previously expanded state. In everyday clinical practice, this term is almost always used specifically to refer to pulmonary atelectasis, meaning the loss of air contained within the tiny air sacs of the lungs, called alveoli, which leads to the compacting and collapsing of lung tissue in on itself.
Pulmonary Atelectasis
The lungs are a pair of organs located within the chest, protected by the surrounding rib cage, whose essential function is to ensure the continuous exchange of oxygen and carbon dioxide between the blood and the outside air, a process that must continue reliably throughout every moment of a person’s life.
Pulmonary atelectasis refers to the collapse of one or more areas of lung tissue.
When we inhale, the lungs fill with air, which travels into millions of tiny air sacs called alveoli. The tissue surrounding these alveoli is particularly rich in tiny blood vessels (capillaries), which allows oxygen to pass efficiently from the inhaled air directly into the bloodstream.
When the alveoli tend to collapse, essentially deflating much like a balloon losing its air, the amount of air available for gas exchange is drastically reduced. As a direct consequence, the amount of oxygen available to meet the body’s needs can become genuinely insufficient.
Atelectasis can be caused by a reduction in the passage of air toward the lungs, for example due to the presence of excess mucus or an inhaled foreign object blocking the airway. Alternatively, it can occur when the normal expansion of the lung is, for some reason, prevented or made difficult, such as by an underlying lung disease. In practical terms, atelectasis can therefore result from a remarkably wide range of different conditions. In theory, essentially any cause that makes it difficult to take sufficiently deep breaths, or to cough effectively (in order to clear any mucus present within the airways), can potentially lead to a partial or complete lung collapse.
Atelectasis frequently develops following surgery performed under general anesthesia, since the medications used during general anesthesia can profoundly affect the normal mechanics of breathing, often leading to shallower breaths and reduced lung expansion during and after the procedure.
Atelectasis may go completely unnoticed if it affects only a small portion of lung tissue, since the remaining healthy lung can typically compensate adequately. In cases of more extensive involvement, however, it can manifest with fever, shallow and/or wheezing breathing, and coughing.
Generally speaking, atelectasis is not life-threatening, but in certain cases it must be treated promptly in order to prevent it from becoming so.
For diagnostic purposes, imaging tests, such as a chest X-ray, and, when necessary, bronchoscopy, play a decisive role in confirming the diagnosis.
Treatment can involve, depending on the specific underlying cause, breathing exercises, medications, devices designed to support and improve breathing, or, in some cases, surgical intervention. Atelectasis generally improves over time or with appropriate treatment.
If it is not promptly recognized and treated, however, atelectasis can potentially progress toward more serious complications, including a dangerous buildup of fluid, pneumonia, and respiratory failure.
Atelectasis or Pneumothorax?
It is worth clarifying an important distinction that is sometimes a source of confusion. When the collapse involves the entire lung, and results specifically from the presence of air trapped between the lung and the chest wall, the condition is instead referred to as pneumothorax. When, on the other hand, only a portion of the lung, whether small or relatively extensive, is affected, the term atelectasis is used. While both conditions involve a form of lung collapse, their underlying mechanisms, causes, and typical treatments differ significantly, which is why distinguishing between them is an important first step in the diagnostic process.
Causes
The underlying causes of pulmonary atelectasis can, for teaching purposes, be conveniently divided into three main categories:
Obstructive Atelectasis
This occurs in the presence of a blockage within the airways, which can result, for example, from:
- an accumulation of excess mucus within the airway;
- inhalation of a foreign object;
- a tumor that develops directly within the airway itself, physically obstructing the passage of air.
Non-Obstructive Atelectasis
This category can be further divided into two distinct mechanisms:
Compression atelectasis, which occurs when the lung is subjected to external pressure from a surrounding structure. Conditions associated with this mechanism include:
- an accumulation of fluid within the pleural space (known as a pleural effusion), meaning within the thin, sac-like membrane that surrounds the lungs and normally allows them to expand smoothly with each breath;
- physical trauma, such as from an injury or a fall, which can prevent normal breathing due to pain, leading the patient to instinctively take excessively shallow breaths in order to avoid discomfort;
- pneumonia;
- a tumor located outside the airway itself, which reduces the lung’s capacity to expand normally through a direct compressive effect on surrounding lung tissue.
Contraction atelectasis (also called cicatrization atelectasis), which occurs when the lung’s inability to expand normally is related to a progressive replacement of healthy lung tissue with scar tissue, a process known as pulmonary fibrosis.
Anesthesia-Related Atelectasis
General anesthesia represents a particularly common cause of obstructive atelectasis related to mucus accumulation. This occurs as a direct consequence of the altered breathing pattern induced by anesthetic medications, which can lead to a gradual loss of volume within the lung’s alveoli due to mucus buildup that is not adequately cleared during the procedure. From this perspective, patients undergoing cardiac bypass surgery are considered particularly susceptible to developing this condition, given the length and nature of the procedure.
Pulmonary atelectasis can occur at any age and for a wide variety of reasons. In newborns, for example, it can result from insufficient maturation of the lungs, which can in turn lead to the development of respiratory distress syndrome, a serious condition affecting premature infants whose lungs have not yet fully developed.
Risk Factors
The primary risk factor for developing atelectasis is a prolonged period of bed rest, particularly when combined with a reduction in normal changes of body position, shallow breathing patterns, and the presence of an underlying lung disease. Closely related to this is, understandably, having recently undergone surgery, especially when performed under general anesthesia.
Among the other predisposing factors are:
- injuries that make breathing painful, such as a cracked or broken rib;
- smoking;
- obesity;
- sleep apnea syndrome;
- underlying lung diseases such as asthma, Chronic Obstructive Pulmonary Disease (COPD), or cystic fibrosis.
Symptoms
When the area of lung tissue affected by collapse is relatively small, atelectasis may produce no noticeable symptoms whatsoever, since the remaining, unaffected portion of the lung is generally capable of adequately compensating for the reduced surface area available for oxygen-carbon dioxide exchange.
In the presence of more extensive lung damage, however, the patient may instead experience:
- breathlessness and air hunger;
- shallow and wheezing breathing;
- tachycardia (an abnormally rapid heart rate), occurring as the body’s natural compensatory reaction to reduced oxygen levels;
- chest pain;
- cyanosis (a bluish discoloration of the fingers and lips resulting from insufficient blood oxygenation);
- coughing.
Complications
The overall prognosis of pulmonary atelectasis is generally closely tied to the specific underlying condition responsible for its development. In the absence of specific additional risk factors, the prognosis is typically excellent, barring recurrences, which can occur more frequently in the context of conditions that are not fully curable, such as cystic fibrosis and pulmonary fibrosis.
In cases where atelectasis affects a significant portion of the lung, however, it is possible to develop complications that can become genuinely serious, including:
- Hypoxemia (a reduction in the amount of oxygen available in the blood);
- Pneumonia, since collapsed, poorly ventilated lung tissue provides an environment where bacteria can more easily proliferate;
- Respiratory failure, which, in the most severe cases, can potentially have a fatal outcome if not promptly recognized and treated.
Diagnosis
To diagnose atelectasis, once it has been reasonably suspected based on the patient’s reported symptoms and clinical history, the physician typically proceeds with a chest X-ray, and, when further detail is required, a CT scan.
Ultrasound can also potentially contribute to the diagnostic process by helping to differentiate between atelectasis, pleural effusion, and pulmonary parenchymal consolidation (a condition in which a region of the lung has become filled with fluid rather than air, as commonly occurs in pneumonia).
In more severe or complex cases, a more invasive diagnostic test, bronchoscopy, may be used to directly visualize the interior of the airways by inserting a small, flexible tube equipped with a camera into the respiratory tract. When an obstruction to airflow is identified during this procedure, it is sometimes possible to address and treat the blockage during the same procedure, combining diagnosis and treatment in a single session.
To support the patient throughout the diagnostic and treatment process, continuous monitoring of oxygen saturation using a pulse oximeter, a small, non-invasive device typically clipped onto a finger, can also provide valuable, real-time information about the patient’s respiratory status.
Treatment
The majority of cases of atelectasis improve without requiring specific treatment, beyond close and continuous monitoring of the patient’s condition. In more severe cases, however, the therapeutic approach depends essentially on the underlying cause and the overall severity of the condition, and can include:
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Breathing exercises, designed to encourage deeper breaths and promote re-expansion of collapsed lung tissue;
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Postural drainage, a technique in which the patient’s body is positioned so that the head is lower than the chest, using gravity to help promote the clearance of mucus from the affected areas of the lung;
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Medications aimed at treating the specific underlying lung condition responsible for triggering the atelectasis;
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Bronchoscopy and/or surgery, for example to physically remove any obstruction blocking the normal passage of air through the airway;
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Oncological (cancer) treatment, in cases where atelectasis has developed as a consequence of an underlying tumor.
Prevention
Practicing deep breathing exercises and voluntary coughing techniques following surgical procedures can meaningfully reduce the risk of developing atelectasis in patients considered to be at increased risk, such as those recovering from major surgery or general anesthesia. Many hospitals now routinely provide patients with a simple device called an incentive spirometer, which encourages deep, sustained breaths and provides visual feedback to help patients perform these exercises correctly and consistently during recovery.
From a broader, general health perspective, promoting an overall healthy lifestyle is certainly advisable as a preventive measure. In this specific context, this includes quitting smoking and, when appropriate, losing excess weight if necessary, since both smoking and obesity represent well-established, modifiable risk factors for the development of atelectasis and other respiratory complications.
Sources and Bibliography
- National Institutes of Health (NIH), MedlinePlus. Atelectasis
- Mayo Clinic. Atelectasis: Symptoms and causes
- Cleveland Clinic. Atelectasis
- American Thoracic Society. Atelectasis
- Grott K, Chauhan S, Dunlap JD. Atelectasis. In: StatPearls. Treasure Island (FL): StatPearls Publishing; 2023.
