What is the management for abnormal respiratory findings post cardiac surgery?

Management of Abnormal Respiratory Findings Post Cardiac Surgery

Non-invasive ventilation (NIV) should be used as the first-line treatment for patients with post-operative acute respiratory failure following cardiac surgery. 1

Assessment of Respiratory Complications

• Systematic respiratory assessment should include monitoring of oxygen saturation, respiratory rate, work of breathing, and breath sounds 2
• Common respiratory complications after cardiac surgery include:
  • Acute respiratory distress syndrome (ARDS) - most common cause of respiratory failure (26.8% of cases) 3
  • Exacerbation of COPD and bronchial asthma (16.1% of cases) 3
  • Diaphragmatic dysfunction (11.7% of cases) 3
  • Pneumonia (10.8% of cases) 3
  • Pulmonary congestion (8.7% of cases) 3

Management Algorithm

First-Line Interventions

• Non-invasive ventilation (NIV) for patients with post-operative acute respiratory failure 1

  • NIV reduces the risk of tracheal re-intubation within 7 days (33% vs 46% with standard oxygen therapy) 1
  • NIV decreases the incidence of healthcare-associated infections (31% vs 49% with standard oxygen therapy) 1
  • Both CPAP and bilevel NIV are effective in improving clinical outcomes 1

• Early mobilization and respiratory physiotherapy to prevent atelectasis and promote lung expansion 2

  • Implement as soon as hemodynamically stable 4
  • Include deep breathing exercises, incentive spirometry, and assisted coughing techniques 2

Ventilation Strategies

• For patients requiring mechanical ventilation:

  • Use protective lung ventilation strategy with low tidal volumes (6-8 mL/kg ideal body weight) 2, 5
  • Apply moderate positive end-expiratory pressure (PEEP) 1
  • Consider PEEP during cardiopulmonary bypass to protect the lungs 1
  • Maintain driving pressure as low as possible 5

• For patients with impaired cough (peak cough flow <270 L/min):

  • Use manually assisted cough and mechanical insufflation-exsufflation techniques 2
  • Consider extubation directly to NIV for patients with poor respiratory function 2

Pharmacological Management

• Bronchodilator therapy for patients with bronchospasm or COPD exacerbation

  • Albuterol via nebulizer or inhaler 6
  • Caution: monitor for paradoxical bronchospasm and cardiac effects with beta-agonists 6

• Anti-inflammatory therapy

  • High-dose dexamethasone (1 mg/kg) may be considered for lung protection in selected patients 1
  • Reduces incidence of prolonged ventilation (>24h) from 4.9% to 3.4% 1
  • Reduces postoperative pneumonia from 10.6% to 6% 1

Special Considerations

• For patients with ARDS:

  • Mortality rate varies by severity (15.1% for mild/moderate ARDS, 75% for severe ARDS) 3
  • Maintain low tidal volumes and optimal PEEP 5
  • Consider prone positioning if not contraindicated by surgical wound 5
  • Extracorporeal techniques may be considered in experienced centers for severe cases 5

• For patients with right heart dysfunction:

  • Carefully consider the effect of mechanical ventilation on right ventricular function 5
  • Avoid excessive PEEP which may increase right ventricular afterload 5

Prevention of Respiratory Complications

• Biocompatible modifications of cardiopulmonary bypass circuits should be considered to protect lungs from inflammatory responses 1

• Modified ultrafiltration (MUF) and selective pulmonary artery perfusion may improve postoperative respiratory function 1

• Avoid hyperoxia during cardiopulmonary bypass as it is not recommended for lung protection 1

Monitoring for Complications

• For respiratory deterioration, assess for potential surgical complications such as bleeding, tamponade, or pneumothorax 2

• Monitor for signs of ventilator-associated pneumonia, which occurs in approximately 40.6% of patients with respiratory failure 3

• Respiratory failure is associated with increased hospital mortality (15.5% vs 2.4% in patients without respiratory failure) and reduced long-term survival 7

Risk Factors for Respiratory Complications

• Highest incidence of respiratory failure occurs after combined valve/CABG procedures (14.8%) and aortic procedures (13.5%) 7

• Other risk factors include preoperative renal failure, hemodynamic instability, and use of intraaortic balloon pump 7

• Off-pump coronary artery bypass is associated with lower incidence of respiratory failure compared to on-pump procedures (1.6% vs 3.5%) 3