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Tuesday, August 21, 2012

Atelectasis Partial lung collapse

Atelectasis is the collapse of part or (much less commonly) all of a lung.
 Atelectasis may be an acute or chronic condition. In acute atelectasis, the lung has recently collapsed and is primarily notable only for airlessness. In chronic atelectasis, the affected area is often characterized by a complex mixture of airlessness, infection, widening of the bronchi


Atelectasis

Partial lung collapse

Classification

Atelectasis may be an acute or chronic condition. In acute atelectasis, the lung has recently collapsed and is primarily notable only for airlessness. In chronic atelectasis, the affected area is often characterized by a complex mixture of airlessness, infection, widening of the bronchi (bronchiectasis), destruction, and scarring (fibrosis).


Chronic atelectasis may take one of two forms—middle lobe syndrome or rounded atelectasis. In right middle lobe syndrome (also known as Andy Wilson's Disease), the middle lobe of the right lung contracts, usually because of pressure on the bronchus from enlarged lymph glands and occasionally a tumor. The blocked, contracted lung may develop pneumonia that fails to resolve completely and leads to chronic inflammation, scarring, and bronchiectasis.
In rounded atelectasis (folded lung syndrome), an outer portion of the lung slowly collapses as a result of scarring and shrinkage of the membrane layers covering the lungs (pleura). This produces a rounded appearance on x-ray that doctors may mistake for a tumor. Rounded atelectasis is usually a complication of asbestos-induced disease of the pleura, but it may also result from other types of chronic scarring and thickening of the pleura.


Absorption Atelectasis

The atmosphere is composed of 78% nitrogen and 21% oxygen. Since oxygen is exchanged at the alveoli-capillary membrane, nitrogen is a major component for the alveoli's state of inflation. If a large volume of nitrogen in the lungs is replaced with oxygen, the oxygen may subsequently be absorbed into the blood reducing the volume of the alveoli, resulting in a form of alveolar collapse known as absorption atelectasis.


Causes, incidence, and risk factors

Atelectasis is caused by a blockage of the air passages (bronchus or bronchioles) or by pressure on the outside of the lung.
It is common after surgery, or in patients who were in the hospital.
Risk factors for developing atelectasis include:
  • Anesthesia
  • Foreign object in the airway (most common in children)
  • Lung diseases
  • Mucus that plugs the airway
  • Pressure on the lung caused by a buildup of fluid between the ribs and the lungs (called a pleural effusion)
  • Prolonged bed rest with few changes in position
  • Shallow breathing (may be caused by painful breathing)
  • Tumors that block an airway

Symptoms

  • Breathing difficulty
  • Chest pain
  • Cough

Signs and tests

  • Bronchoscopy
  • Chest CT scan
  • Chest x-ray

Treatment

The goal of treatment is to re-expand the collapsed lung tissue. If fluid is putting pressure on the lung, removing the fluid may allow the lung to expand.
The following are treatments for atelectasis:
  • Clap (percussion) on the chest to loosen mucus plugs in the airway
  • Perform deep breathing exercises (with the help of incentive spirometry devices)
  • Remove or relieve any blockage by bronchoscopy or another procedure.
  • Tilt the person so the head is lower than the chest (called postural drainage). This allows mucus to drain more easily.
  • Treat a tumor or other condition, if there is one
  • Turn the person to lie on the healthy side, allowing the collapsed area of lung to re-expand
  • Use aerosolized respiratory treatments (inhaled medications) to open the airway
  • Use other devices that help increase positive pressure in the airways and clear fluids (positive and expiratory pressure [PEP] devices)

Expectations (prognosis)

In an adult, atelectasis in a small area of the lung is usually not life threatening. The rest of the lung can make up for the collapsed area, bringing in enough oxygen for the body to function.
Large areas of atelectases may be life threatening, especially in a baby or small child, or someone who has another lung disease or illness.
The collapsed lung usually reinflates slowly if the blockage of the airway has been removed. However, some scarring or damage may remain.

Complications

Pneumonia may develop quickly after atelectasis in the affected part of the lung.

Prevention

  • Encourage movement and deep breathing in anyone who is bedridden for long periods.
  • Keep small objects out of the reach of young children.
  • Maintain deep breathing after anesthesia.

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