Atelectasis The 5 Minute Pediatric Consult
Elizabeth C. Uong and Richard Mark
Kravitz
DEFINITION
- State of collapsed and airless alveoli
- May be subsegmental, segmental, or lobar, or may involve the whole lung
- A radiographic sign of disease and not a diagnosis in itself
CAUSES
(TYPES/MECHANISMS)
- Resorption atelectasis (also called obstructive atelectasis); obstructed
communication between alveoli and trachea
- Large airway obstruction
- Intrinsic: e.g., foreign-body aspiration, mucus plug, inflammatory
(TB, sarcoid), tumor
- Extrinsic: e.g., hilar adenopathy, mediastinal masses, cardiomegaly,
congenital malformations
- Small airway obstruction
- Altered mucociliary clearance: e.g., pain, CNS depression, smoke
inhalation
- Chronic obstructive airway disease: e.g., asthma, cystic fibrosis
- Acute infection: e.g., acute bronchiolitis, pneumonia
- Adhesive atelectasis: stems from surfactant deficiency
- Diffuse surfactant deficiency: e.g., hyaline membrane disease, ARDS,
smoke inhalation
- Localized surfactant deficiency: e.g., acute radiation pneumonitis,
pulmonary embolism, pneumonia
- Passive atelectasis: e.g., loss of lung volume due to shifts in
intrapleural pressure
- Diaphragmatic abnormalities: e.g., paralysis, congenital eventration
- Hypoventilation: e.g., post-anesthesia; inherent neuromuscular weakness
(e.g., muscular dystrophy)
- Compressive atelectasis: mechanical compression of the pulmonary
parenchyma or pleural space
- Intrathoracic: e.g., tension pneumothorax, pleural effusion, lobar
emphysema, intrathoracic tumors, diaphragmatic hernias
- Abdominal distension: e.g., large intraabdominal tumors,
hepatosplenomegaly, massive ascites, morbid obesity
- Cicatrization atelectasis: stems from decreased lung compliance secondary
to fibrosis
- Generalized pulmonary fibrosis: e.g., sarcoidosis, collagen vascular
diseases, idiopathic pulmonary fibrosis
- Localized pulmonary fibrosis: e.g., bronchiectasis, chronic tuberculosis
and fungal diseases
- Gravity-dependent atelectasis: result of gravity-dependent alterations in
alveolar volume (e.g., bedridden patients with poor mucociliary clearance;
pulmonary edema)
PATHOPHYSIOLOGY
- Reduced lung compliance
- Loss of alveoli (if extensive) may lead to hypoxia.
- Intrapulmonary shunting develops from hypoxia-induced pulmonary arterial
vasoconstriction.
- If atelectasis is extensive, pulmonary hypertension may develop.
- Atelectatic areas are prone to bacterial over-growth.
GENETICS
Depends on the underlying disease causing
atelectasis
EPIDEMIOLOGY
- Depends on the underlying disease causing atelectasis; resorption
atelectasis most common
COMPLICATIONS
- Recurrent infections
- Bronchiectasis
- Hemoptysis
- Abscess formation
- Fibrosis of the pulmonary parenchyma
PROGNOSIS
- Depends on underlying disease process
- In general, excellent
- Pneumonia
- Viral pneumonia versus subsegmental atelectasis
- Bacterial pneumonia versus segmental or lobar atelectasis
- Thymus (atelectasis in upper lobe)
- Congenital malformations (i.e., sequestration, bronchogenic cyst)
- Pleural effusion
HISTORY
Special Questions
Question: Is there history of asthma, chronic
lung disease, exposure to smoke or toxic fumes?
Significance: These
are some of the conditions that may cause atelectasis.
Question: Is there fever or difficulty
breathing?
Significance: These may be asymptomatic.
Question: Is there a
cough?
Significance: Cough can be present, but not in all
cases.
Question: Is there any dyspnea or chest
pain?
Significance: Acute pneumothorax may cause
atelectasis.
- May be normal
- Tachypnea
- Rales or rhonchi
- The most specific sign is localized loss of breath sounds.
- Dullness to percussion if large area involved
- Tracheal deviation and shift of heart sounds toward atelectatic side
- Localized wheezes in cases of partial obstruction
- Cyanosis in those with extensive atelectasis, causing impairment of
oxygenation
Special Question
- Is the atelectasis acute, recurrent, or chronic?
TESTS
Depending on Underlying
Disease
- Bronchoscopy can be useful for evaluation of possible:
- Foreign body aspiration
- H-type tracheoesophageal fistula (TEF)
- Bronchial stenosis
Infection
- Cultures (sputum, blood)
- Nasal washing (especially for viruses)
- Skin testing (PPD if tuberculosis suspected)
- Asthma
- Spirometry
- Cystic fibrosis
- Sweat test
Immunodeficiency
- CBC with differential
- Immunoglobulins (IgG, IgA, IgM)
Lung Malformations
Imaging
Chest Radiography
- Most important diagnostic tool
- Radiographic signs of atelectasis
- Direct signs, i.e., crowded pulmonary vessels, crowded air bronchograms,
displacement of interlobar fissures
- Indirect signs, i.e., pulmonary opacification, elevation of diaphragm,
displacement of trachea, hilum; approximation of ribs; compensatory
hyperexpansion of surrounding lung
CT of Chest
- Confluence of bronchi and blood vessels that converge toward the
atelectatic side
- Provides information in regard to precise location and extent of
obstructing process
PITFALLS
- If the proximal bronchi are occluded or filled with secretions, air
bronchograms may not be seen, and displacement of the interlobar fissures may
be the only direct sign of atelectasis.
- The indirect signs of atelectasis are not constant, and one or more signs
might be absent. Lung opacification may not be apparent until a considerable
amount of volume loss has occurred. When atelectasis is bilateral, the trachea
and the mediastinum usually remain in the midline. Close approximation of the
ribs may also occur from poor positioning—this sign by itself may be an
unreliable indicator of atelectasis.
- Treat underlying disease: e.g., removal of aspirated foreign body
- Chest physical therapy with bronchodilators—usually for at least 1 month
- If no improvement with conservative therapy, bronchoscopy with lavage to
remove possible mucus plug
- Surgery to remove affected region if chronic, unresponsive to therapy, or
significant morbidity seen
- Prevention: directed toward underlying cause, when applicable; e.g., in
atelectasis secondary to altered mucociliary clearance or chronic airway
obstruction such as in cystic fibrosis or asthma, chest physical therapy
should be given.
WHEN TO EXPECT
IMPROVEMENT
| COMMON
QUESTIONS AND ANSWERS |
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|
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Q: When is the optimal time for
bronchoscopy?
A: There are no established criteria. Bronchoscopy
should be done early in the course of disease if there is high suspicion of a
foreign body or significant respiratory distress, or if atelectasis is extensive
and conservative treatment is ineffective. Most isolated atelectatic areas will
improve during a 3-month period with appropriate therapy; thus, bronchoscopy
should be postponed, if possible, for at least this period.
Karlson KH. Pediatric respiratory disease:
diagnosis and treatment. Philadelphia: WB Saunders, 1993:436–440.
Oermann CM, Moore RH. Foolers: things that look like
pneumonia in children. Semin Respir Infect 1996;11:204–213.
Redding GJ. Atelectasis in childhood. Pediatr Clin
North Am 1984;31:891–905.
Woodring JH, Reed JC. Types and mechanisms of
pulmonary atelectasis. J Thorac Imaging 1996;11:92–108.
Copyright
© 2000 Lippincott Williams & Wilkins
M. William
Schwartz, Louis M. Bell, Jr., Peter M. Bingham, Esther K. Chung, David F.
Friedman and Andrew E. Mulberg, The 5 Minute Pediatric Consult