Atelectasis: Symptoms, Types, Causes and Treatment

Atelectasis is a medical term describing the collapse or closure of lung tissue, which leads to reduced or absent gas exchange. This condition is surprisingly common, especially in hospital and postoperative settings, but also occurs in various other medical scenarios. Understanding atelectasis—the symptoms, its types, underlying causes, and effective treatments—empowers patients, families, and healthcare professionals to recognize and manage this condition early, minimizing complications and improving outcomes.

Symptoms of Atelectasis

Atelectasis can present with a range of symptoms, from very subtle to quite distressing. The signs often depend on the size and location of the collapsed lung area, underlying causes, and whether the onset is sudden or gradual. In some cases, especially if only a small lung region is affected, patients may have no symptoms at all. However, larger or rapidly developing atelectasis tends to produce more noticeable effects.

Symptom	Description	Severity/Onset	Source(s)
Shortness of breath	Difficulty breathing or feeling breathless	Sudden or gradual	5, 11
Cough	Dry or productive cough	Common, variable	11
Chest pain	Discomfort or pain in chest	Sometimes present	5, 11
Low oxygen saturation	Decreased blood oxygen levels	Measured by tests	5, 12
Rapid heart rate	Increased heart rate (tachycardia)	Especially with hypoxia	10
No symptoms	Especially with small areas involved	Often in mild cases	1

Table 1: Key Symptoms

Symptom Details and Clinical Manifestations

Shortness of Breath and Respiratory Distress

Shortness of breath is the most frequent and prominent symptom, especially when a significant portion of the lung is affected. This is due to reduced lung volume and impaired oxygenation. Patients may notice difficulty catching their breath, especially with exertion or when lying down 5, 11.

Cough and Chest Discomfort

Atelectasis often produces a cough, which can be dry or sometimes productive if infection is also present. Chest pain or a sense of discomfort may be noted, but this is generally less severe than with other lung conditions like pneumonia or pulmonary embolism 11.

Hypoxemia and Physiological Changes

Reduction in oxygen exchange can lead to lower blood oxygen saturation, which is detectable on pulse oximetry or arterial blood gas analysis. Severe cases may cause rapid breathing (tachypnea) and increased heart rate as the body compensates for reduced oxygen delivery 5, 10, 12.

Asymptomatic Presentations

It’s important to note that small areas of atelectasis may not produce any symptoms at all and are often discovered incidentally on imaging studies performed for other reasons 1.

Pediatric and Postoperative Considerations

In children, especially those with infections or underlying lung disease, atelectasis may present with increased work of breathing, irritability, and reduced feeding. After surgeries—particularly heart or abdominal procedures—patients are monitored closely for any signs of respiratory compromise 3, 12.

Types of Atelectasis

Atelectasis is not a single, uniform entity. Its classification depends on both the mechanism of lung collapse and the anatomical extent. Recognizing the type is crucial for guiding effective management and understanding potential complications.

Type	Defining Feature	Common Mechanism	Source(s)
Resorptive	Collapse distal to airway blockage	Airway obstruction	1, 11
Compressive	Collapse from external pressure	Mass, effusion, pneumothorax	1, 11
Adhesive	Loss of surfactant	Surfactant deficiency	1, 8
Passive	Reduced lung expansion	Diaphragm dysfunction, hypoventilation	1
Cicatrization	Collapse from scarring	Pulmonary fibrosis	1
Gravity-dependent	Collapse in dependent lung areas	Prolonged immobility	1
Rounded	Localized, rounded opacity	Pleural fibrosis/adhesion	2
Subsegmental	Small, plate-like collapse	Minor airway blockage	1

Table 2: Types of Atelectasis

Classification Explained

Resorptive (Obstructive) Atelectasis

This is the most common type, resulting from blockage of a bronchus or bronchiole by mucus, tumor, or foreign body. Air distal to the obstruction is gradually absorbed, leading to collapse of the affected lung segment or lobe 1, 11.

Compressive Atelectasis

Here, external pressure from sources like pleural effusion (fluid), pneumothorax (air), tumors, or even abdominal distension compresses the lung, causing it to collapse. The lung tissue itself is intact, but cannot expand due to the outside force 1, 11.

Adhesive Atelectasis

This type is caused by a deficiency or dysfunction of surfactant, a molecule that reduces surface tension in the lungs. Without adequate surfactant, the alveoli stick together and collapse—seen in premature infants and acute lung injury 1, 8.

Passive Atelectasis

Occurs when the lung fails to expand properly due to decreased movement of the chest wall or diaphragm, as seen in patients with diaphragmatic paralysis or those on prolonged bed rest 1.

Cicatrization Atelectasis

Develops from scarring (fibrosis) of lung tissue, often after chronic inflammation, infection, or exposure to toxins. The scar tissue contracts, pulling the lung tissue closed 1.

Gravity-dependent Atelectasis

When patients are immobile for long periods (such as during anesthesia or critical illness), gravity leads to collapse of the dependent (lower) lung regions 1.

Rounded Atelectasis

A unique form, rounded atelectasis appears as a mass-like, rounded opacity, often in association with pleural diseases—especially after asbestos exposure or pleural effusion. It’s important to differentiate this from tumors 2.

Subsegmental (Platelike) Atelectasis

This involves small, linear areas of collapse, often seen as “platelike” or “discoid” opacities on imaging. Usually due to minor airway blockage or hypoventilation 1.

Causes of Atelectasis

Atelectasis itself is a manifestation of an underlying problem; it rarely occurs in isolation. Identifying and addressing the root cause is essential for effective management and prevention of recurrence.

Cause	Mechanism	Risk Group/Setting	Source(s)
Airway obstruction	Blockage by mucus, tumor, etc.	Hospitalized, children, post-op	1, 11
External compression	Mass, fluid, air in pleural space	Trauma, heart/lung disease	1, 11
Surfactant deficiency	High surface tension, alveolar collapse	Premature infants, acute lung injury	1, 3, 8
Prolonged immobility	Gravity-dependent collapse	Critical care, anesthesia	5, 7, 8
Infection/inflammation	Mucus plugging, scarring	Pneumonia, chronic lung disease	1, 11
Surgical procedures	Reduced lung expansion, mucus retention	Postoperative patients	5, 8, 12
Pleural disease	Adhesion, fibrosis	Asbestos exposure, effusions	2

Table 3: Common Causes of Atelectasis

Underlying Mechanisms and Risk Factors

Airway Obstruction

Blockage of the airway is the classic cause—by mucus plugs (common after surgery or in children), tumors, foreign bodies (especially in children), or thick secretions resulting from infection or dehydration 1, 11. This leads to resorptive (obstructive) atelectasis.

External Compression

Fluid accumulation (pleural effusion), pneumothorax, or masses adjacent to the lung can compress lung tissue from the outside, leading to collapse 1, 11.

Surfactant Deficiency

Premature newborns are especially vulnerable due to immature lungs with insufficient surfactant, leading to adhesive atelectasis. Surfactant can also be inactivated or depleted during acute lung injury (such as ARDS) or after certain medical interventions 1, 3, 8.

Prolonged Immobility and Anesthesia

Hospitalized patients, especially those under general anesthesia or on mechanical ventilation, are at risk. Anesthesia leads to loss of muscle tone, decreased lung volumes, and altered gas exchange, all contributing to atelectasis formation 5, 7, 8. Obese patients and those with chronic lung disease are at higher risk 7.

Infection, Inflammation, and Scarring

Infections can cause mucus plugging or chronic inflammation leading to fibrosis (cicatrization), which in turn results in persistent atelectasis 1, 11.

Postoperative Factors

Surgical patients are prone due to effects of anesthesia, pain (leading to shallow breathing), impaired coughing, and increased mucus production or retention 5, 8, 12.

Pleural Diseases

Chronic pleural diseases, especially those caused by asbestos or recurrent effusions, can lead to pleural scarring and adhesion. This may produce rounded atelectasis, which can resemble a tumor on imaging 2.

Treatment of Atelectasis

Managing atelectasis involves both relieving the lung collapse and addressing the underlying cause. The approach is tailored to the patient’s condition, severity of atelectasis, and risk factors. Early intervention can restore lung function and prevent complications such as pneumonia.

Treatment	Method/Approach	Indication/Population	Source(s)
Chest physiotherapy	Postural drainage, percussion	Mild-moderate cases	5, 9, 11
Early mobilization	Getting patient out of bed	Postoperative, critical care	12
Positive airway pressure	PEEP, CPAP, recruitment maneuvers	Severe, ventilated patients	7, 13
Bronchodilators	Inhaled medications	Bronchospasm, mucus plugging	11
Bronchoscopy	Direct removal of blockage	Persistent obstruction	11, 13
DNase therapy	Nebulized/enzyme treatment	Children, mucus-related	10
Addressing cause	Treating infection, draining effusion	Varies by etiology	1, 11

Table 4: Treatment Strategies

Approaches to Management

Chest Physiotherapy and Mobilization

Physical interventions such as postural drainage, chest percussion, and deep breathing exercises help loosen and mobilize secretions, promoting lung re-expansion. Early mobilization—encouraging patients to sit up and move soon after surgery—has been shown to reduce the risk and severity of atelectasis, especially in cardiac surgery patients 5, 9, 11, 12.

Positive Airway Pressure

Applying positive end-expiratory pressure (PEEP) or continuous positive airway pressure (CPAP) helps keep alveoli open, particularly in patients on mechanical ventilation or those with significant hypoxemia. Recruitment maneuvers (briefly inflating the lungs at higher pressures) can rapidly re-inflate collapsed areas, though care is needed to avoid lung injury 7, 13.

Medical Management

Bronchodilators may be used if there is evidence of bronchospasm or to help mobilize secretions. In children, DNase (an enzyme that breaks down DNA in mucus) has been used with success in selected cases of mucus-related atelectasis 10.

Bronchoscopy

When mucus plugs or foreign bodies persist, bronchoscopy may be required to directly clear the obstruction. This is especially true in cases that do not respond to conservative measures 11, 13.

Treating the Underlying Cause

It is crucial to address the root problem: antibiotics for pneumonia, drainage of pleural effusions, removal of tumors, or surfactant replacement in neonates with deficiency 1, 11.

Prevention

In the perioperative setting, strategies include using the lowest effective oxygen concentration, regular recruitment maneuvers, and minimizing periods of immobility 7, 8, 12.

Novel and Adjunct Therapies

Combined kinetic therapy (e.g., specialized beds that turn patients) and mechanical percussion have shown promise in resolving atelectasis more rapidly in critically ill patients 9.

Conclusion

Atelectasis is a common and clinically significant lung condition that can arise in numerous medical settings. Prompt recognition and targeted management are essential to restore lung function and prevent complications. Here’s a summary of what we’ve covered:

• Atelectasis is lung collapse that impairs oxygen exchange; symptoms range from subtle to severe breathlessness.
• Types include resorptive, compressive, adhesive, passive, cicatrization, gravity-dependent, rounded, and subsegmental forms, each with unique features and mechanisms.
• Causes are diverse: airway obstruction, external compression, surfactant deficiency, immobility, infections, surgery, and pleural disease are key contributors.
• Treatment is multifaceted, involving chest physiotherapy, early mobilization, positive airway pressure, medications, bronchoscopy, and addressing the underlying cause.
• Prevention—especially in at-risk groups like surgical and critically ill patients—is vital for reducing the incidence and severity of atelectasis.

By understanding the diverse presentations and underlying mechanisms of atelectasis, both healthcare providers and patients can take proactive steps towards better lung health and recovery.