What is atelectasis in the Cardiovascular Intensive Care Unit (CVICU), its signs and symptoms, treatment options, and relevant CVICU tips?

Atelectasis in CVICU: Signs, Symptoms, Treatment, and Management Tips

Atelectasis in the CVICU is a state of collapsed and non-aerated lung regions that requires prompt identification and management to prevent severe complications including hypoxemia and respiratory failure. 1

Definition and Mechanisms

Atelectasis describes collapsed and non-aerated regions of otherwise normal lung parenchyma. In the CVICU setting, it occurs through three primary mechanisms:

• Airway obstruction (mucous plugging, secretion retention) 2
• Compression of lung parenchyma (from cardiac surgery, pleural effusions, pneumothorax) 3
• Increased surface tension in alveoli (surfactant dysfunction, often seen post-anesthesia) 4, 5

Atelectasis is particularly concerning in CVICU patients as it occurs in approximately 90% of anesthetized patients and can persist for several days postoperatively, potentially becoming a focus of infection and contributing to pulmonary complications. 5

Signs and Symptoms

Common clinical manifestations include:

• Decreased oxygen saturation and hypoxemia (may be severe) 6
• Diminished or absent breath sounds over affected areas 1
• Tachypnea and increased work of breathing 7
• Asymmetric chest wall movement during ventilation 1
• Increased peak airway pressures in mechanically ventilated patients 4
• Radiographic findings: areas of opacification, volume loss, and displacement of fissures on chest X-ray 2

Diagnostic Approach

• Monitor for signs of atelectasis through observation of bilateral chest wall expansion during ventilation 1
• Utilize lung ultrasound or chest X-ray to confirm diagnosis and extent of atelectasis, especially when there is doubt about bilateral lung ventilation 1
• Differentiate from lobar consolidation, which may present similarly on imaging 2

Treatment Strategies

Ventilation Management

• Apply positive end-expiratory pressure (PEEP) of 6-15 cmH2O, with higher PEEP for moderate to severe cases 1
• Perform recruitment maneuvers (inflation of lungs to airway pressure of 40 cmH2O for 7-8 seconds) to re-expand collapsed lung tissue 5
• Ensure endotracheal tube cuff pressure is maintained at 20-30 cmH2O to prevent leaks while avoiding excessive pressure on the tracheal mucosa 1
• Use moderate fraction of inspired oxygen (FiO2 0.3-0.4) after recruitment maneuvers to prevent rapid reappearance of atelectasis 5

Secretion Management

• Implement regular chest physiotherapy and postural drainage 2
• Consider acetylcysteine as adjuvant therapy for patients with abnormal, viscid, or inspissated mucous secretions causing atelectasis 8
• Use closed tracheal suction systems to minimize aerosol generation and maintain lung volume 1
• Remove persistent mucous plugs via bronchoscopy when other measures fail 2

Post-Extubation Support

• Consider high-flow oxygen therapy via nasal cannula after extubation for hypoxemic patients 1
• Use non-invasive ventilation (NIV) after extubation for patients at high risk of reintubation, especially those with hypercapnia 1
• Provide physiotherapy before and after extubation for patients ventilated for more than 48 hours 1

CVICU-Specific Tips

• Check endotracheal tube cuff pressure and depth before and after any patient repositioning to prevent tube displacement 1
• Consider using an endotracheal tube with a subglottic suction port to help manage secretions 1
• During procedures requiring circuit disconnection: ensure adequate sedation, consider neuromuscular blockade, pause the ventilator, clamp the endotracheal tube, and separate the circuit with the heat and moisture exchanger filter attached to the patient 1
• Be vigilant for heat and moisture exchange filter blockage, which can cause increased airway resistance that may be mistaken for patient deterioration 1
• Monitor for tube displacement during sedation holds 1
• In obese patients, expect larger atelectatic areas and implement more aggressive preventive strategies 4

Prevention Strategies

• Avoid high fractions of oxygen during induction and maintenance of anesthesia 5
• Perform intermittent recruitment maneuvers followed by PEEP to reduce atelectasis and pulmonary shunt 4
• Properly position endotracheal tubes and record tube depth at every shift 1
• Implement early mobilization when clinically appropriate 7
• Consider having a physiotherapist attend endotracheal extubation to limit immediate complications 1