What are the indications for home Non-Invasive Ventilation (NIV) in patients with chronic respiratory failure, such as Chronic Obstructive Pulmonary Disease (COPD), neuromuscular diseases like Amyotrophic Lateral Sclerosis (ALS), or Obesity Hypoventilation Syndrome?

Home Non-Invasive Ventilation Indications

Home NIV is indicated for patients with chronic stable hypercapnic respiratory failure (resting PaCO₂ >45 mmHg) from COPD, obesity hypoventilation syndrome, neuromuscular diseases, and chest wall deformities, assessed 2-4 weeks after resolution of any acute exacerbation. 1

Primary Disease-Specific Indications

COPD

• Initiate home NIV in COPD patients with chronic stable hypercapnic respiratory failure (FEV₁/FVC <0.70; resting PaCO₂ >45 mmHg) measured when clinically stable, not during acute exacerbation. 2, 1
• Screen all COPD patients for obstructive sleep apnea before initiating long-term NIV, as comorbid OSA may require higher EPAP settings to maintain upper airway patency. 2, 1
• High-intensity NIV with targeted normalization of PaCO₂ reduces hospital readmissions and improves survival in COPD patients with persistent hypercapnia. 1, 3
• Consider home NIV for COPD patients who have had three or more episodes of acute hypercapnic respiratory failure in the previous year. 2

Obesity Hypoventilation Syndrome

• Home NIV is indicated for patients with obesity hypoventilation syndrome presenting with chronic hypercapnic respiratory failure (PaCO₂ >45 mmHg during clinical stability). 1
• Patients with OHS treated with NIV during acute hypercapnic respiratory failure have lower hospital mortality (6% vs 18% in COPD) and better outcomes than COPD patients. 4

Neuromuscular Diseases

• Home NIV is indicated for hypercapnic respiratory failure secondary to neuromuscular diseases including amyotrophic lateral sclerosis, myopathies, and Duchenne muscular dystrophy. 1, 5
• All patients with neuromuscular disease who develop acute hypercapnic respiratory failure should be referred for assessment to a center providing long-term ventilation at home. 2
• NIV is life-prolonging in patients with amyotrophic lateral sclerosis who develop chronic respiratory failure. 6
• ALS patients require more interface trials than other groups and often need progressive adjustment of settings over time to achieve adequate ventilation. 7

Chest Wall Deformities

• Home NIV is indicated for hypercapnic respiratory failure secondary to chest wall deformity including scoliosis and thoracoplasty. 1, 5
• All patients with spinal cord lesions or chest wall deformity who develop acute hypercapnic respiratory failure should be referred for assessment to a center providing long-term ventilation at home. 2

Critical Timing for Assessment

Post-Acute Exacerbation Protocol

• Do not initiate long-term NIV during an admission for acute-on-chronic hypercapnic respiratory failure; instead, reassess for NIV at 2-4 weeks after resolution. 2, 1
• All patients treated with NIV for acute hypercapnic respiratory failure should undergo spirometric testing and arterial blood gas analysis while breathing air prior to discharge. 2
• If pre-discharge arterial blood gas shows PaO₂ <7.3 kPa in COPD patients, repeat measurement after at least 3 weeks; if hypoxemia persists with hypercapnia, consider nocturnal NIV. 2

Physiological Criteria for Initiation

Gas Exchange Requirements

• Resting daytime PaCO₂ >45 mmHg measured during clinical stability (not during acute exacerbation) is the primary criterion for home NIV initiation. 1
• For COPD specifically, persistent hypercapnia must be documented 2-4 weeks after acute exacerbation resolution. 1, 3
• If the patient is hypercapnic while breathing air or if PaCO₂ rises significantly with administration of supplementary oxygen to correct hypoxemia, consider NIV. 2

Absolute Contraindications

Do not initiate home NIV in patients with:

• Recent facial or upper airway surgery 1, 5
• Facial burns or trauma 1, 5
• Fixed upper airway obstruction 1, 5
• Active vomiting 1, 5
• Recent upper GI surgery 1, 5

Relative Contraindications Requiring Caution

• Severe bulbar dysfunction 1, 5
• Copious secretions that cannot be cleared 1, 5
• Deteriorating consciousness requiring immediate intubation 1, 5
• Undrained pneumothorax (must position adequate chest drain before starting NIV) 1

Initial Ventilator Settings

Standard Pressure Settings

• Start with IPAP 10-15 cmH₂O and EPAP 4-8 cmH₂O for most patients. 1, 5
• Use lower pressures for neuromuscular patients: IPAP 8-12 cmH₂O, EPAP 3-5 cmH₂O. 1, 5
• Maintain pressure difference between IPAP and EPAP of at least 5 cmH₂O to ensure adequate ventilation. 1

High-Intensity NIV for COPD

• For COPD patients with frequent exacerbations, use high-intensity NIV with inspiratory pressures higher than baseline and controlled ventilation with higher respiratory rates to maximally reduce PaCO₂. 3
• Set backup respiratory rate equal to or slightly less than patient's spontaneous sleeping respiratory rate (minimum of 10 breaths/min). 3

Monitoring and Titration

• In-laboratory overnight polysomnogram is not necessary to titrate NIV in patients with chronic stable hypercapnic COPD who are initiating NIV. 2, 3
• Arterial blood gases should be checked after 30-60 minutes of ventilation and monitored regularly to ensure effective reduction in PaCO₂. 3
• Target normalization of PaCO₂ for patients with hypercapnic COPD on long-term NIV. 2, 3

Common Pitfalls to Avoid

• Patient compliance decreases over time, even over short periods—establish early follow-up protocols. 1, 3
• Failure to screen for obstructive sleep apnea before NIV initiation in COPD patients leads to suboptimal outcomes. 1, 3
• Initiating NIV during acute hospitalization rather than waiting 2-4 weeks post-exacerbation results in inappropriate patient selection. 1
• Using inadequate pressure support (pressure difference <5 cmH₂O) leads to ineffective ventilation. 1
• Failing to refer patients who cannot be weaned from NIV within one week after acute episode to a center providing home NIV. 2