Atelectasis – Causes, Symptoms, Diagnosis, Treatment and Ongoing care

Basics

Description

• Atelectasis is the collapse of otherwise normal lung tissue.
• A variety of causes exist (see Etiology).
• It can reduce respiratory gas exchange, leading to hypoxemia if severe.
• It can increase the risk of developing pneumonia.
• It may be an asymptomatic finding on chest x-ray (CXR).
• Diagnosis and therapy are directed at the underlying etiology.

Epidemiology

• Predominant age: All ages
• Predominant sex: Male = Female

Incidence

Common

Prevalence

Common

Risk Factors

• General anesthesia (1)
• Common postoperatively, particularly following thoracic or upper abdominal surgery, prolonged or emergency surgery, and vascular surgery (1,2)[A]
• Risk factors for developing atelectasis after surgery:
  • Age >60
  • ASA class II+
  • Functional dependence in activities of daily living
  • Heart failure
  • Smoking (1)
• Intensive care and prolonged immobilization (3)

General Prevention

Encourage activity and mobilization.

Pathophysiology

See Description and Etiology

Etiology

• Obstructive (resorptive) atelectasis: Intrinsic airway obstruction:
  • Most common type; due to luminal blockage (foreign body, mucous plug, asthma, cystic fibrosis, trauma, tumor) or airway wall abnormality (congenital malformation, emphysema)
• Compressive atelectasis: Extrinsic airway compression:
  • Direct compression of airways: Lymphadenopathy, tumor, abscess, cardiomegaly
  • Relaxation atelectasis: Loss of contact between parietal and visceral pleura
  • Chest wall restriction: Trauma, scoliosis, or chest wall tumor
• Cicatrization: Pleural or parenchymal lung scarring:
  • Granulomatous disease, toxic inhalation, drug-induced fibrosis (e.g., amiodarone); asbestosis or infection (tuberculosis [TB]) often results in round atelectasis (see Imaging).
• Adhesive atelectasis:
  • Surfactant impairment due to anesthesia, adult respiratory distress syndrome; primary surfactant deficiency in preterm infants
• Other:
  • Hypoxemia due to pulmonary embolus
  • Muscular weakness (anesthesia, neuromuscular disease)

Commonly Associated Conditions

• Chronic obstructive pulmonary disease
• Asthma
• Trauma
• Acute respiratory distresss syndrome (ARDS)
• Neonatal respiratory distress syndrome
• Pulmonary edema
• Pulmonary embolism
• Neuromuscular disorders
• Cystic fibrosis
• Respiratory syncytial virus (RSV) bronchiolitis (infants and toddlers)

Diagnosis

History

• Frequently asymptomatic
• Tachypnea
• Cough
• Pleuritic pain

Physical Exam

• Hypoxia
• Dullness to percussion
• Bronchial breathing if airway is patent
• Absent breath sounds if airway is occluded
• Diminished chest expansion
• Wheezing may be heard with focal obstruction.
• Tracheal or precordial impulse displacement

Diagnostic Tests & Interpretation

Lab

Initial lab tests

Sputum culture if infection is suspected

Follow-Up & Special Considerations

Albumin level: Low serum albumin level (<3.5 g/L) is a powerful marker of increased risk for postoperative pulmonary complications, including atelectasis (1).

Imaging

Initial approach

• CXR (posterior-anterior and lateral):
  • Raised diaphragm, flattened chest wall, movement of fissures and mediastinal structures toward the atelectatic region
  • Unaffected lung may show compensatory hyperinflation.
  • Wedge-shaped densities: Obstructive atelectasis
  • Small, linear bands (Fleischner lines) often at lung bases: Discoid (subsegmental or plate) atelectasis
  • Air bronchograms: Evidence of pleural fluid or air may indicate compressive atelectasis.
  • Adhesive atelectasis may present as a diffuse reticular granular pattern progressing to a pulmonary edema-like pattern and finally to bilateral opacification in severe cases.
  • Pleural-based round density on CXR: Round atelectasis

Follow-Up & Special Considerations

Chest computed tomography (CT) or magnetic resonance imaging (MRI) may be indicated to visualize airway and mediastinal structures and to identify cause of atelectasis.

Diagnostic Procedures/Surgery

• Bronchoscopy to assess airway patency in unexplained or refractory cases
• Echocardiography to assess cardiac status in cardiomegaly
• Barium swallow to assess mediastinal vascular compression

Pathological Findings

• Needle biopsy is rarely needed for diagnosis.
• Pathology varies with underlying cause.

Differential Diagnosis

Atelectasis is not a specific diagnosis, but rather a result of disease or distorted anatomy. The differential is found under Etiology.

Treatment

Medication

First Line

• Therapies directed at basic cause: Antibiotics for infection, chemo/radiation therapy for tumor, steroids for asthma
• Analgesia for pain control to permit deep inspiration and coughing

Pediatric Considerations

• Rh DNAse may be effective in clearing mucinous secretions in persistent atelectasis in children (4)[C].

Second Line

Bronchodilator therapy (β-agonist aerosol); efficacy controversial

Additional Treatment

General Measures

• Ensure adequate oxygenation (may start with 100% FiO₂ then taper) and humidification.
• If known, treat the underlying cause.
• Ensure patient is lying on the unaffected side to promote drainage:
  • Maximize patient mobility and encourage frequent coughing and deep breathing every hour (physical therapy).
• Incentive spirometry
• Initiate intubation and mechanical ventilation with positive end-expiratory pressure (PEEP) in severe respiratory distress or hypoxemia:
  • Lower tidal volume (6 mL/kg) and lower end-inspiratory values (<30 mm Hg) associated with reduced mortality (5)[B]
  • PEEP 15–20 mL may be necessary to maintain arterial O₂ saturation in surfactant-impaired states (5)[B].
• Obstructive atelectasis: Suction and vigorous coughing to remove obstruction, then physical therapy and bronchoscopy to remove obstruction if previous measures fail:
  • Bronchoscopy as therapy is controversial other than for large airway obstruction removal.
• Postsurgical measures include positive airway pressure, continuous or intermittent in the postoperative patient (6)[A].

Issues for Referral

As needed for underlying etiology

Additional Therapies

As listed under General Measures

Surgery/Other Procedures

Only for resectable underlying disease (e.g., tumor, severe lymphadenopathy)

In-Patient Considerations

Initial Stabilization

Ensure adequate oxygenation (may start with 100% FiO₂ then taper) and humidification.

Admission Criteria

As determined by underlying etiology

IV Fluids

As needed for underlying etiology

Nursing

As listed under General Measures

Discharge Criteria

As allowed by underlying etiology

Ongoing Care

Follow-Up Recommendations

Patient Monitoring

• Varies with cause and patient status
• In simple atelectasis associated with asthma or infection, outpatient visits are adequate.

Diet

No special diet

Patient Education

Maximize patient mobility and encourage frequent coughing and deep breathing every hour.

Prognosis

• Spontaneous resolution
• Resolution with medical therapy
• Surgical therapy needed only for resectable causes or if chronic infection and bronchiectasis supervene

Complications

• Atelectasis is rarely life-threatening and usually resolves spontaneously.
• Acute atelectasis:
  • Hypoxemia and respiratory failure
  • Postobstructive drowning of the lung
  • Pneumonia
• Chronic atelectasis:
  • Bronchiectasis
  • Pleural effusion and empyema

References

1. Qaseem A, Snow V, Fitterman N et al. Risk assessment for and strategies to reduce perioperative pulmonary complications for patients undergoing noncardiothoracic surgery: a guideline from the American College of Physicians. Ann Intern Med. 2006;144:575–80.

2. Ferreyra G, Long Y, Ranieri VM, et al. Respiratory complications after major surgery. Curr Opin Crit Care. 2009;15:342–8

3. Brower RG, et al. Consequences of bed rest. Crit. Care Med. 2009;37:S422–8

4. Hendriks T, de Hoog M, Lequin MH et al. DNase and atelectasis in non-cystic fibrosis pediatric patients. Crit Care. 2005;9:R351–6.

5. McCunn M, et al. Guidelines for management of mechanical ventilation in critically injured patients. Trauma Care 2004;14(4):147–51.

6. Lawrence VA, Cornell JE, Smetana GW et al. Strategies to reduce postoperative pulmonary complications after noncardiothoracic surgery: systematic review for the American College of Physicians. Ann Intern Med. 2006;144:596–608.

Additional Reading

Muders T, Wrigge H, et al. New insights into experimental evidence on atelectasis and causes of lung injury. Best Pract Res Clin Anaesthesiol. 2010;24:171–82

Hedenstierna G, Edmark L, et al. Mechanisms of atelectasis in the perioperative period. Best Pract Res Clin Anaesthesiol. 2010;24:157–69

See Also (Topic, Algorithm, Electronic Media Element)

Algorithm: Ascites

Codes

ICD9

518.0 Pulmonary collapse

Snomed

46621007 Atelectasis (disorder)

Clinical Pearls

• Atelectasis is not a specific diagnosis but rather a result of disease or distorted anatomy.
• A number of different etiologies exist.
• Treatment of underlying etiology is key.