What are the guidelines for initiating Non-Invasive Ventilation (NIV) in Chronic Obstructive Pulmonary Disease (COPD) patients, including initial Inspiratory Positive Airway Pressure (IPAP) and Expiratory Positive Airway Pressure (EPAP) settings, adjustment criteria, and indications for home use?

Guidelines for NIV Initiation in COPD Patients

Non-invasive ventilation (NIV) should be initiated in COPD patients with hypercapnic respiratory failure (PaCO2 >45 mmHg) that persists despite maximal medical treatment and appropriate controlled oxygen therapy, using bi-level pressure support with initial IPAP of 10-12 cmH2O and EPAP of 4-5 cmH2O. 1

Indications for NIV in COPD

• Acute hypercapnic respiratory failure with:

  • Respiratory acidosis (PaCO2 >45 mmHg, pH <7.35)
  • Respiratory distress (respiratory rate >25 breaths/min)
  • SpO2 <90% despite appropriate oxygen therapy 2, 1

• Patients with pH <7.25 respond less well and should be managed in HDU/ICU 2

Initial NIV Setup Protocol

1. Determine management plan if NIV fails (document in notes)
2. Decide appropriate location (ICU, HDU, or respiratory ward)
3. Consider informing ICU
4. Explain NIV to patient
5. Select appropriate mask and fit to patient
6. Initial ventilator settings:
   • Mode: Bi-level pressure support (BiPAP)
   • IPAP: 10-12 cmH2O
   • EPAP: 4-5 cmH2O
   • Pressure support (IPAP minus EPAP): 6-8 cmH2O
   • Backup rate: 12-14 breaths/min 2, 1
7. Attach pulse oximeter
8. Start NIV, holding mask in place initially
9. Secure mask with straps/headgear
10. Reassess after a few minutes
11. Add oxygen if SpO2 <85%
12. Instruct patient on mask removal and how to call for help 2

Monitoring and Adjustment of NIV Settings

• Check arterial blood gases at 1-2 hours after initiation
• Adjust settings based on response:

If PaCO2 remains elevated:

• Check for excessive oxygen (adjust FiO2 to maintain SpO2 85-90%)
• Check for mask leaks and circuit setup
• Consider increasing IPAP to improve ventilation
• Consider increasing EPAP in COPD to reduce work of breathing
• Check patient-ventilator synchrony 2, 1

If PaO2 remains low despite improved PaCO2:

• Increase FiO2

• Consider increasing EPAP 2

• Target normalization of PaCO2 in patients with hypercapnic COPD on long-term NIV 2, 1

• Response to NIV should be evident at 1 hour and certainly by 4-6 hours 2, 1

When to Stop NIV

• Institute alternative management plan if:

  • PaCO2 and pH have deteriorated after 1-2 hours of NIV on optimal settings
  • No improvement in PaCO2 and pH by 4-6 hours 2

• Other indications to stop NIV:

  • Development of complications (pneumothorax, sputum retention, nasal bridge erosion)
  • Intolerance or poor synchrony with ventilator
  • Failure to alleviate symptoms
  • Deteriorating consciousness level
  • Patient/carer wish to withdraw treatment 2

Indications for Home NIV in COPD

• Chronic stable hypercapnic COPD (PaCO2 >45 mmHg while stable) 2, 1
• Persistent hypercapnia after an acute exacerbation 1
• Multiple previous hospital admissions for COPD exacerbation requiring ventilatory support 1, 3
• COPD patients with BMI >30 kg/m² respond particularly well to home NIV 3
• Consider home NIV if NIV is still needed more than one week after acute episode 2
• Consider for patients who have had three or more episodes of acute hypercapnic respiratory failure in the previous year 2

Important Clinical Considerations

• NIV should be initiated and run by trained staff (nurses, physiotherapists, doctors) 2
• For home NIV, high-intensity NIV with higher inspiratory pressures (20-25 cmH2O) has shown better outcomes in reducing PaCO2 and improving survival 3, 4
• Do not initiate long-term NIV during admission for acute-on-chronic hypercapnic respiratory failure; reassess 2-4 weeks after resolution 2
• Screen for obstructive sleep apnea before initiating long-term NIV 2, 1
• Early NIV use in appropriate COPD patients reduces need for intubation by 65% and mortality by 46% 1, 5

By following these guidelines, NIV can effectively reduce work of breathing, improve gas exchange, prevent need for invasive mechanical ventilation, and reduce mortality in COPD patients with hypercapnic respiratory failure.