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.