Atelectasis: Imperfect Expansion of Lungs, Causes, Symptoms, Treatment

What is Atelectasis?

Atelectasis is also called as collapse of lung. It is an imperfect expansion of the lung. It may be confined to a segment, a lobe or the whole lung.

What are the Causes of Atelectasis?

Congenital causes of Atelectasis

It is also referred to as neonatal collapse. Non-aeration of lung at birth or developing soon after birth is not uncommon in premature or low birth weight babies because of under developed lungs.
It is also associated with neonatal hyaline membrane disease, laryngeal dysfunction and obstruction of air passage.

Acquired causes of Atelectasis

Acquired atelectasis is of 2 types:

Compression collapse: It occurs due to external compression of the lung as in pleural effusion, haemothorax, and pneumothorax or rarely by surgical procedures such as thoracoplasty.
Absorption collapse: It is more common and is produced by bronchial obstruction.
Intraluminal causes of obstruction are foreign body, inspissated mucus, tumors and aspirations of gastric contents e.g. during unconscious state or during anesthesia.
Causes within the wall of bronchus causing collapse include bronchial stricture, often due to tuberculosis or tumors.
Extrinsic causes: pressure on bronchus by enlarged lymph nodes, aortic aneurysm or enlarged left atrium may also lead to atelectasis.

What are the Symptoms of Atelectasis?

A slowly developing atelectasis of a lobe may produce no symptoms.
A sudden or quick developing atelectasis is characterized by breathlessness and cough.
Massive atelectasis may be associated with cyanosis, tachycardia, restlessness and even circulatory collapse.
Limitation of chest excursion on the affected side and shift of trachea and heart to the same side.
Percussion note over collapsed area is impaired.
Bronchial breathing with bronchophony may be heard.
Massive atelectasis may be complicated by acute respiratory failure.
Repeated infections in atelectatic lobe may be present as recurrent pneumonia.

How does one detect Atelectasis?

Chest X-ray usually confirms the diagnosis in form of a shrunken lung, lobe or segment. Displacement of the fissure, elevation of diaphragm and a change in position of mediastinal structures are important clues to underlying atelectasis.
Bronchoscopy is mandatory in all cases of obstructive collapse.
Examination of bronchial expirate for acid fast bacilli and cytology is necessary.
CT-scan helps to locate a mass or lymph node as the cause for atelectasis.

What Treatments are available for Atelectasis?

After a chest or major abdominal surgery deep breathing exercises, steam inhalation and encouragement to cough should be given to prevent post operative atelectasis.
Specific treatment depends upon cause of collapse. If effusion or pneumothorax is responsible, this external compression should be removed first.
Aspirated material, mucus plugs and foreign body need bronchoscopic removal.

Aspiration Pneumonia: Symptoms, Causes and Treatment

Aspiration pneumonia

Aspiration pneumonia is a type of secondary pneumonia or pneumonia due to weak host defenses. Aspiration pneumonia is caused by aspiration of organisms (usually anaerobes) into to lower respiratory tract.

Benign aspiration pneumonia

In this type of aspiration pneumonia the cause is due to aspiration of infected nasal secretions into lower respiratory tract
due to coryza or sinusitis. These organisms are usually of low virulence and the degree of systemic disturbance is usually slight. Infact symptoms are often no more severe than lower respiratory tract infections and existence of pneumonia may be discovered only on chest X-ray.

Symptoms of Benign aspiration pneumonia

Cough
Purulent sputum
Low grade fever and
Sometimes pleuritic chest pain in association with frank upper respiratory tract infection.
Neutrophilic luecocytosis is usually present.
Chest X-ray shows unilateral mottled opacity involving a single lobe or segment.

Re-examination 10-14 days later, following treatment with antibiotic usually helps as resolution is generally rapid.

Symptoms of other types of Aspiration Pneumonia

In other type of aspiration pneumonia there is pneumonic consolidation in which there is destruction of lung parenchyma by inflammatory process.
Usually caused by staphylococcus aureus or klebsiella pneumoniae.
These are in effect, primary bacterial pneumonias with pulmonary suppuration.

Causes of aspiration pneumonia

Altered consciousness.
Dysphagia and esophageal diseases e.g. tracheo-esphageal fistula.
Naso-gastric tubes.
Severe dental and upper airways sepsis- especially during dental extraction.
Terminal illness.
Gastro-esophageal reflux during general anesthesia.

Organisms isolated in above cases from sputum include streptococcus pneumoniae, staphylococcus auerus, streptococcus pyogen, haemophilus influenza and few cases anaerobic bacterias.

Clinical features of aspiration pneumonia

Usually depend on extent of aspiration material into lower respiratory tract.
Onset may be acute or incidious.
Cough with purulent sputum, is usually in large amounts which is sometimes foetid and blood stained, is present from an early stage.
Person has high, remittent fever with shivering and sweating.
Pleuritic chest pain is common and digital clubbing may be seen 10-14 days after onset of illness.
Progressive deterioration of general health occurs if person remains untreated.
Neutrophilic luecocytosis is seen on complete blood count.
Signs of consolidation or collapse are seen unilaterally involving single lobe or segment. Signs of cavitations are usually not seen.

Prevention of Aspiration Pneumonia

Every precaution should be taken during surgeries of mouth, nose and throat to prevent inhalation of blood.
Oral sepsis should be eradicated in case general anesthesia is given.

Treatment of Aspiration Pneumonia

Rest in bed and ambulation as soon as signs of toxicity disappear.
Deep breathing exercises.
Mechanical procedures like broncho-scopic suction for removal of aspirated material to prevent collapse as well as to find the causative organism after sending BAL (brochoscopic aspiration lavage) sample for culture sensitivity.
Anti-microbial therapy is started at earliest usually based on the type of organism isolated in culture.