atelectasis | 5 minute clinical consultation (2023)

Description

• atelectasisIt is defined as the incomplete expansion of lung tissue due to collapse or occlusion. Loss of lung volume and function results in impaired mucus clearance from the airways.
• Roughly categorized as:
  • Obstructive: obstruction of the airways
  • Non-obstructive: loss of contact between parietal and visceral pleura, replacement of lung tissue due to scarring or infiltrative disease, surfactant dysfunction, and parenchymal compression
• Symptoms depend on the rate of collapse, the affected lung, and whether the patient has underlying lung disease and/or comorbidities.
• Decreased respiratory gas exchange can cause hypoxemia.

Epidemiology

• The average age is 60, but all ages are susceptible.
• male = female; no racial or socioeconomic preference

accident

• Roundedatelectasisit can be seen in up to 65-70% of asbestos workers.
• loboatelectasisit is variable depending on collateral ventilation and the number of lobes involved.

frequency
postoperativeatelectasis, especially after major cardiovascular or gastrointestinal (GI) surgery; can be seen in up to 90% of patients

Etiology and pathophysiology

• obstructive (resorptive)atelectasisit is caused by an intrinsic blockage of the airways and is the most common variant. It can be caused by a luminal blockage (ie foreign body, mucus plug, asthma, cystic fibrosis, trauma, massive injury) or an abnormality in the airway wall (ie congenital malformation and emphysema).
  • Distal to the obstruction, alveolar air is rapidly reabsorbed into the deoxygenated venous system, causing complete collapse of the alveolar tissue.
  • Percentage of inspired oxygen (FiO₂): Compared to the rapid dissociation of O₂distal to the obstruction, the 79% atmospheric nitrogen in the atmosphere dissociates more slowly from the alveoli. This prevents collapse by maintaining a positive pressure in the alveoli. However, with increasing FiO₂, the nitrogen concentration is reduced, which allows a rapid development ofatelectasisat the beginning of the obstruction.
  • The patency and function of the collateral ventilation systems in each lobe (Kohn's pores, Lambert's canals, and Boren's windows) depend on several patient factors, including age, underlying lung disease, and FiO.₂.
  • Perforated windows are enlarged in patients with emphysema, which works as a compensatory mechanism and can lead to delayed inhalation.atelectasisdespite an obstructing lesion or mass.
• clearatelectasis
  • Passiveatelectasis(ie, during a pleural effusion or pneumothorax) is due to separation of the pleural membrane from the visceral and parietal layers.
  • CompressionatelectasisOccurs with massive lesions, cardiomegaly, abscesses, or marked lymphadenopathy.
    • Increased pressure on the chest wall compresses the alveoli, resulting in decreased functional residual capacity (FRC) or decreased resting lung volume.
  • stickeratelectasisin acute respiratory distress syndrome (ARDS), radiation, smoke inhalation or uremia. The underlying surfactant dysfunction causes increased surface tension and alveolar collapse.
  • Scarring represents pleural or parenchymal scarring and is common in granulomatous disease (i.e., sarcoidosis), toxic or radiation exposure, and drug-induced fibrosis (i.e.,amiodarone,cyclophosphamide).
  • Substituteatelectasis: manifestation of a diffuse tumor (i.e. bronchoalveolar cell carcinoma) leading to complete flap collapse
• Roundedatelectasisit's a different way ofatelectasisobserved in patients with asbestos exposure as a result of their significant pleural disease.
• Others
  • Hypoxemia due to pulmonary embolism
  • Muscle weakness: due to a side effect of anesthesia or in neuromuscular disorders involving the respiratory muscles

pediatric considerations
Children are at greater risk of developingatelectasisdue to its less developed compensatory and collateral ventilatory mechanisms.

Risk factors

• Intensive care and prolonged immobilization
• General anesthesia (including long-acting muscle relaxants, postoperative epidural)
• positive fluid balance
• Massive blood transfusion (≥4 units)
• Nasogastric tube placement
• hypothermia
• Mechanical ventilation with high tidal volume (Vt >10 mL/kg) and plateau pressure (>30 cm H₂Ö)
• Patient risk factors for the postoperative periodatelectasis:
  • Age >60 years and <6 years
  • Chronic Obstructive Pulmonary Disease (COPD)
  • obstructive sleep apnea
  • Heart failure (CHF)
  • alcohol abuse, smoking
  • Pulmonary hypertension
  • Albumina < 3,5 g/dl
  • Hemoglobina < 10 g/dl
  • IMC > 27 kg/m²(weak evidence)
  • ASA Class II+ Functional Dependence in Activities of Daily Living (ADL)
  • Surgical interventions: cardiothoracic, vascular, upper gastrointestinal, neurosurgical, oromaxillofacial and otorhinolaryngological
  • Often a precursor to more serious postoperative pulmonary complications (1)
• Right middle lobe syndrome (Brock's syndrome): wedge-shaped density extending downward and forward from the hilum. It is best visualized on a lateral chest X-ray; no uniform clinical definition

general prevention

• Early mobilization, deep breathing exercises, coughing, and frequent changes in body position

• Preoperative physiotherapy reduced the rates ofatelectasis, pneumonia and length of stay (LOS) in patients undergoing elective cardiac surgery. However, there was no change in other postoperative pulmonary complications or mortality (2)[A]. Furthermore, large RCTs are needed before conclusions can be drawn about the effectiveness of chest physiotherapy and incentive spirometry (IS).

• Mechanical ventilation settings with high Vt (Vt >10 mL/kg) and plateau pressures (>30 cm H₂O) and the absence of positive end-expiratory pressure (PEEP) are associated with postoperative pulmonary complications (eg, pneumonia, respiratory failure):
  • Minimize ventilator-associated injuries by using low Vt and plateau pressures with adequate PEEP.
  • Provide lowest FiO₂during induction of anesthesia and intraoperatively to avoid nitrogen leakage.
• Continuous positive airway pressure (CPAP) during anesthesia induction and anesthesia-induced anesthesia reversalatelectasisafter intubation by a recruitment maneuver, postoperative pulmonary complications may be reduced (3)[C].

Commonly Associated Conditions

• Obstructive lung diseases (COPD and asthma)
• Trauma
• ARDS, neonatal IBS, pulmonary edema, pulmonary embolism, pneumonia, pleural effusion, pneumothorax
• Respiratory syncytial virus (RSV), bronchiolitis
• bronchial stenosis, pulmonary valve disease and pulmonary hypertension
• Neuromuscular diseases (muscular dystrophy, spinal muscular atrophy, spinal cord injury and Guillain-Barré syndrome) and cystic fibrosis

Description

• atelectasisIt is defined as the incomplete expansion of lung tissue due to collapse or occlusion. Loss of lung volume and function results in impaired mucus clearance from the airways.
• Roughly categorized as:
  • Obstructive: obstruction of the airways
  • Non-obstructive: loss of contact between parietal and visceral pleura, replacement of lung tissue due to scarring or infiltrative disease, surfactant dysfunction, and parenchymal compression
• Symptoms depend on the rate of collapse, the affected lung, and whether the patient has underlying lung disease and/or comorbidities.
• Decreased respiratory gas exchange can cause hypoxemia.

Epidemiology

• The average age is 60, but all ages are susceptible.
• male = female; no racial or socioeconomic preference

accident

• Roundedatelectasisit can be seen in up to 65-70% of asbestos workers.
• loboatelectasisit is variable depending on collateral ventilation and the number of lobes involved.

frequency
postoperativeatelectasis, especially after major cardiovascular or gastrointestinal (GI) surgery; can be seen in up to 90% of patients

Etiology and pathophysiology

• obstructive (resorptive)atelectasisit is caused by an intrinsic blockage of the airways and is the most common variant. It can be caused by a luminal blockage (ie foreign body, mucus plug, asthma, cystic fibrosis, trauma, massive injury) or an abnormality in the airway wall (ie congenital malformation and emphysema).
  • Distal to the obstruction, alveolar air is rapidly reabsorbed into the deoxygenated venous system, causing complete collapse of the alveolar tissue.
  • Percentage of inspired oxygen (FiO₂): Compared to the rapid dissociation of O₂distal to the obstruction, the 79% atmospheric nitrogen in the atmosphere dissociates more slowly from the alveoli. This prevents collapse by maintaining a positive pressure in the alveoli. However, with increasing FiO₂, the nitrogen concentration is reduced, which allows a rapid development ofatelectasisat the beginning of the obstruction.
  • The patency and function of the collateral ventilation systems in each lobe (Kohn's pores, Lambert's canals, and Boren's windows) depend on several patient factors, including age, underlying lung disease, and FiO.₂.
  • Perforated windows are enlarged in patients with emphysema, which works as a compensatory mechanism and can lead to delayed inhalation.atelectasisdespite an obstructing lesion or mass.
• clearatelectasis
  • Passiveatelectasis(ie, during a pleural effusion or pneumothorax) is due to separation of the pleural membrane from the visceral and parietal layers.
  • CompressionatelectasisOccurs with massive lesions, cardiomegaly, abscesses, or marked lymphadenopathy.
    • Increased pressure on the chest wall compresses the alveoli, resulting in decreased functional residual capacity (FRC) or decreased resting lung volume.
  • stickeratelectasisin acute respiratory distress syndrome (ARDS), radiation, smoke inhalation or uremia. The underlying surfactant dysfunction causes increased surface tension and alveolar collapse.
  • Scarring represents pleural or parenchymal scarring and is common in granulomatous disease (i.e., sarcoidosis), toxic or radiation exposure, and drug-induced fibrosis (i.e.,amiodarone,cyclophosphamide).
  • Substituteatelectasis: manifestation of a diffuse tumor (i.e. bronchoalveolar cell carcinoma) leading to complete flap collapse
• Roundedatelectasisit's a different way ofatelectasisobserved in patients with asbestos exposure as a result of their significant pleural disease.
• Others
  • Hypoxemia due to pulmonary embolism
  • Muscle weakness: due to a side effect of anesthesia or in neuromuscular disorders involving the respiratory muscles

pediatric considerations
Children are at greater risk of developingatelectasisdue to its less developed compensatory and collateral ventilatory mechanisms.

Risk factors

• Intensive care and prolonged immobilization
• General anesthesia (including long-acting muscle relaxants, postoperative epidural)
• positive fluid balance
• Massive blood transfusion (≥4 units)
• Nasogastric tube placement
• hypothermia
• Mechanical ventilation with high tidal volume (Vt >10 mL/kg) and plateau pressure (>30 cm H₂Ö)
• Patient risk factors for the postoperative periodatelectasis:
  • Age >60 years and <6 years
  • Chronic Obstructive Pulmonary Disease (COPD)
  • obstructive sleep apnea
  • Heart failure (CHF)
  • alcohol abuse, smoking
  • Pulmonary hypertension
  • Albumina < 3,5 g/dl
  • Hemoglobina < 10 g/dl
  • IMC > 27 kg/m²(weak evidence)
  • ASA Class II+ Functional Dependence in Activities of Daily Living (ADL)
  • Surgical interventions: cardiothoracic, vascular, upper gastrointestinal, neurosurgical, oromaxillofacial and otorhinolaryngological
  • Often a precursor to more serious postoperative pulmonary complications (1)
• Right middle lobe syndrome (Brock's syndrome): wedge-shaped density extending downward and forward from the hilum. It is best visualized on a lateral chest X-ray; no uniform clinical definition

general prevention

• Early mobilization, deep breathing exercises, coughing, and frequent changes in body position

• Preoperative physiotherapy reduced the rates ofatelectasis, pneumonia and length of stay (LOS) in patients undergoing elective cardiac surgery. However, there was no change in other postoperative pulmonary complications or mortality (2)[A]. Furthermore, large RCTs are needed before conclusions can be drawn about the effectiveness of chest physiotherapy and incentive spirometry (IS).

  (Video) 5 Minute Clinical Consult

• Mechanical ventilation settings with high Vt (Vt >10 mL/kg) and plateau pressures (>30 cm H₂O) and the absence of positive end-expiratory pressure (PEEP) are associated with postoperative pulmonary complications (eg, pneumonia, respiratory failure):
  • Minimize ventilator-associated injuries by using low Vt and plateau pressures with adequate PEEP.
  • Provide lowest FiO₂during induction of anesthesia and intraoperatively to avoid nitrogen leakage.
• Continuous positive airway pressure (CPAP) during anesthesia induction and anesthesia-induced anesthesia reversalatelectasisafter intubation by a recruitment maneuver, postoperative pulmonary complications may be reduced (3)[C].

Commonly Associated Conditions

• Obstructive lung diseases (COPD and asthma)
• Trauma
• ARDS, neonatal IBS, pulmonary edema, pulmonary embolism, pneumonia, pleural effusion, pneumothorax
• Respiratory syncytial virus (RSV), bronchiolitis
• bronchial stenosis, pulmonary valve disease and pulmonary hypertension
• Neuromuscular diseases (muscular dystrophy, spinal muscular atrophy, spinal cord injury and Guillain-Barré syndrome) and cystic fibrosis