Compression atelectasis J98.1

Atelectasis refers to airless lung tissue that shows no inflammatory changes (Herold 2023).

Atelectasis is divided into primary (found exclusively in premature or newborn infants) and secondary atelectasis (occurring in a previously ventilated area of the lung). Compression atelectasis corresponds to secondary atelectasis (Herold 2023).

Compression atelectasis is most frequently found in the presence of pleural effusions (Mathis 2007).

Compression atelectasis: They are caused by

• compression of the lung tissue from the outside, predominantly in the form of basal squamous atelectasis. They are found, for example, with reduced or abolished diaphragmatic breathing, pleural effusions or diaphragmatic protrusion (Herold 2023).
• postoperative after abdominal surgery: risk factors include obesity, smoking, patient age, diaphragmatic dysfunction, lung disease, intra-abdominal hypertension, general anesthetic drugs such as opioids, sedatives, hypnotics, regional anesthesia, neuromuscular blockers and antagonists, blood transfusions, positioning during surgery (Lagier 2022)
• after a pulmonary embolism
• Middle lobe syndrome: Middle lobe syndrome can occur with atelectasis of the middle lobe due to e.g. enlarged lymph nodes, tuberculosis (Herold 2023)

As soon as the pressure equalization limit is exceeded, the intrapleural pressure leads to compression of the lungs (Kaufmann 2019). This limit is usually reached when the effusion exceeds 2 l (Mathis 2007).

The compressed lung section is anaemic, fibrosis and indurating exudates can form in the pressure zone (Kaufmann 2019).

• Dyspnea (Krombach 2015)
• Hypoxemia
• tachypnea
• Cyanosis
• Possibly pain in the thorax (Kahl- Scholz 2018)

Physical examination:

On auscultation, the breath sound may be attenuated depending on the size of the atelectasis. On percussion, depending on the size of the atelectasis, the percussion sound may be muffled. The vocal fremitus may also be weakened (Kahl-Scholz 2018).

Sonography

Compression atelectasis presents as a wedge-shaped, homogeneous, hypoechoic transformation in the lower lobe (Mathis 2007).

The atelectasis is often detectable over long stretches of the lower edge of the lung (Seitz 2000).

There is usually a blurred border to the air-containing lung tissue. The atelectatic part of the lung is almost always surrounded by fluid (Mathis 2007).

The atelectasis floats concavely in the effusion in a breath-dependent manner and is partially ventilated again during inspiration (Seitz 2000).

If the effusion increases further, the atelectasis only appears as a narrow, echo-like crescent, also referred to as "squamous atelectasis" (Michels 2014).

Chest X-ray

Signs of a reduction in volume are found in the chest X-ray in 2 planes (Herold 2023). In supine radiographs, atelectasis can be recognized less by the reduction in transparency and more by a displacement of the pulmonary fissures (Schaefer-Prokop 2009).

Direct signs of atelectasis are:

• Displacement of the interlobar septum
• Basal strip or plate atelectasis
• Local reduction in transparency with biconcave borders (Herold 2023)

Indirect signs of atelectasis are:

• Displacement of hilar or mediastinum
• Absence of bronchopneumogram
• Diaphragmatic protrusion (Herold 2023)

Congestive pneumonia is sometimes not clearly distinguishable from compression atelectasis by sonography. Here, anamnestic and clinical parameters are indicative of effusion (Seitz 2000).

Atelectasis can lead to the following complications:

• Abscess
• infection
• Respiratory insufficiency (Herold 2023)

Causal therapy by e.g.:

• Drainage or relief of the pleural effusion
• Relief of the airways (Haverkamp 2009)

If there are indications of additional inflammatory changes such as pneumonia or abscess, initiate antibiotic treatment quickly (Herold 2023).

In a chronic form, segmental or lobe resection is necessary (Herold 2023), as otherwise edematous inflammation, bronchiectasis or fibrosis may develop (Online Pschyrembel 2025).

Rapid p. o. mobilization, respiratory therapy and respiratory gymnastics are recommended for the prophylaxis of postoperative compression atelectasis (Herold 2023).

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