What is the recommended Non-Invasive Ventilation (NIV) protocol for a patient with chronic obstructive pulmonary disease (COPD) or other chronic respiratory conditions requiring NIV therapy?

NIV Protocol for COPD and Chronic Respiratory Conditions

Initial Assessment and Patient Selection

Start NIV immediately in patients with COPD exacerbation who have respiratory acidosis (pH <7.35) persisting despite maximal medical treatment and controlled oxygen therapy. 1

• Obtain arterial blood gases before initiating NIV to confirm respiratory acidosis and hypercapnia (PaCO₂ >45 mmHg) 2
• Document a clear decision about endotracheal intubation candidacy before starting NIV in every patient 1
• Screen for obstructive sleep apnea before initiating long-term NIV 1

Contraindications to NIV:

• Impaired consciousness 1
• Severe hypoxemia unresponsive to high-flow oxygen 1
• Copious respiratory secretions 1
• Inability to protect airway 1

Equipment Setup

Use bi-level pressure support (BiPAP) ventilators as first-line equipment, as they are simpler, cheaper, more flexible, and validated in the majority of randomized controlled trials. 1, 2

• Select a full-face mask initially in acute settings, transitioning to nasal mask after 24 hours as the patient improves 1, 2
• Ensure ventilator has pressure capability of at least 30 cmH₂O and can support inspiratory flows of at least 60 L/min 1
• Do not use humidification routinely, as it impairs trigger function 1, 2

Initial Ventilator Settings

Begin with IPAP 10-15 cmH₂O and EPAP 4-8 cmH₂O, maintaining a pressure difference of at least 5 cmH₂O. 2

Specific Parameters:

• IPAP (Inspiratory Positive Airway Pressure): Start at 10-15 cmH₂O 2
• EPAP (Expiratory Positive Airway Pressure): Start at 4-8 cmH₂O to offset intrinsic PEEP and improve breath triggering 2
• Backup rate: 10-14 breaths/min, set equal to or slightly less than patient's spontaneous sleeping respiratory rate 2
• Mode: Spontaneous/Timed (S/T) if patient has frequent central apneas or inappropriately low respiratory rate 2
• Inspiratory time: Set to achieve I:E ratio of approximately 1:2 (30% IPAP time) to prevent air trapping 2

Oxygen Titration:

• Target SpO₂ 88-92% strictly to avoid worsening hypercapnia 2, 1
• Provide controlled oxygen using 24% Venturi mask at 2-3 L/min, nasal cannula at 1-2 L/min, or 28% Venturi mask at 4 L/min before ABG availability 2
• Use pulse oximetry to guide oxygen titration rather than oxygen analyzers in the circuit 2

Treatment Duration and Monitoring

Ventilate patients for as many hours as possible during the first 24 hours (4-20 hours/day), allowing breaks for nebulizers and meals. 1

Early Response Assessment:

• Recheck ABGs after 30-60 minutes of NIV or immediately if clinical deterioration occurs 2
• Expect early improvement in PaO₂, pH, and PaCO₂ within 1 hour, certainly by 4-6 hours 1
• Achieve stability by 4-6 hours 1

Ongoing Monitoring:

• Monitor respiratory rate, dyspnea, and work of breathing continuously 2
• Observe chest expansion to assess ventilation adequacy 1
• Check patient-ventilator synchrony by direct observation 1

Troubleshooting Treatment Failure

If PaCO₂ Remains Elevated:

First verify oxygen is not excessive—adjust FiO₂ to maintain SpO₂ between 85-90%. 1

• Check mask fit for excessive leakage; if using nasal mask, consider chin strap or full-face mask 1
• Verify circuit connections are correct and check for leaks 1
• Check patency of expiratory valve to prevent re-breathing 1
• Increase EPAP if using bi-level pressure support in COPD to improve synchrony 1
• Increase target pressure (IPAP) or volume if ventilation is inadequate 1
• Consider increasing inspiratory time or respiratory rate to increase minute ventilation 1

If PaCO₂ Improves but PaO₂ Remains Low:

• Increase FiO₂ 1
• Consider increasing EPAP with bi-level pressure support 1

Criteria for Intubation

Consider intubation if worsening ABGs and/or pH within 1-2 hours, lack of improvement after 4 hours of NIV, severe acidosis, life-threatening hypoxemia, or altered mental status. 2

• Lack of progress toward correction of pH, PaO₂, and PaCO₂ by 4-6 hours indicates NIV failure 1
• Individual factors include severity of ventilatory failure, likelihood of difficulty weaning from invasive ventilation, patient wishes, and excessive secretions 1
• If NIV clearly fails to palliate symptoms in non-intubation candidates, stop NIV and consider alternative treatment 1

Weaning and Discharge Planning

Most patients wean from NIV within a few days; if still needed after one week, consider referral for long-term home NIV. 1

Pre-Discharge Requirements:

• Perform spirometry and arterial blood gas analysis while breathing air before discharge 1
• If PaO₂ <7.3 kPa in COPD patients, repeat measurement after at least 3 weeks 1
• Consider trial of nocturnal NIV if persistent hypoxemia with hypercapnia on room air or if PaCO₂ rises significantly with supplemental oxygen 1

Referral Indications for Long-Term NIV:

• Failure to wean from NIV 1
• Spinal cord lesions, neuromuscular disease, chest wall deformity, or morbid obesity (BMI >30) with acute hypercapnic respiratory failure 1
• COPD with >3 episodes of acute hypercapnic respiratory failure in previous year 1
• Intolerance of supplemental oxygen due to CO₂ retention with symptomatic sleep disturbance 1

Critical Pitfalls to Avoid

Never use high-flow oxygen—this worsens respiratory acidosis and hypercapnia in COPD patients. 2

• Maintain strict SpO₂ target of 88-92% 2, 1
• Ensure I:E ratio of 1:2 or greater to prevent dynamic hyperinflation and auto-PEEP 2
• If asynchrony cannot be resolved by adjusting trigger sensitivity, switch to timed or assist-control mode 2
• Do not initiate long-term NIV during acute-on-chronic hypercapnic respiratory failure admission; reassess at 2-4 weeks after resolution 1
• Do not use in-laboratory overnight polysomnography to titrate NIV in chronic stable hypercapnic COPD 1

Long-Term NIV Settings

For patients with chronic stable hypercapnic COPD on long-term NIV, target normalization of PaCO₂ using high-intensity NIV. 1

• Use nocturnal NIV in addition to usual care for chronic stable hypercapnic COPD (FEV₁/FVC <0.70; resting PaCO₂ >45 mmHg) 1
• High-intensity NIV refers to higher inspiratory pressures and controlled ventilation with higher respiratory rates to maximally reduce PaCO₂ 1