Management of AECOPD Patients Unable to Wean from NIV
If a patient with AECOPD cannot be weaned from NIV despite optimization, you must first troubleshoot technical issues and optimize ventilator settings, then escalate to invasive mechanical ventilation if pH remains <7.15 or continues deteriorating, or consider long-term home NIV if the patient stabilizes but requires ongoing support. 1
Immediate Troubleshooting Steps
Before declaring NIV failure, systematically address common technical problems that prevent successful weaning 1:
- Check for excessive mask leak - adjust mask fit or change mask type, as leak is the most common cause of NIV failure 1
- Verify adequate pressure support - IPAP should typically be 20-30 cm H₂O (not the commonly under-dosed 15 cm H₂O), with higher pressures needed for larger patients and more severe acidosis 1
- Assess for patient-ventilator asynchrony - caused by mask leak, insufficient/excessive IPAP, inappropriate Ti/Te settings, high intrinsic PEEP, or overly sensitive triggers 1
- Evaluate for positional upper airway obstruction - indicated by variable mask leak; ensure head flexion is avoided 1
- Optimize oxygenation - if hypoxemia persists despite adequate ventilation, increase EPAP to recruit poorly ventilated lung (may also help with upper airway obstruction) 1
Monitoring for True NIV Failure
NIV failure is defined by persisting or worsening acidosis despite optimized NIV delivery 1:
- Physiological parameters (particularly pH and respiratory rate) should improve within 1-2 hours of NIV initiation 1
- Worsening pH and respiratory rate predict increased risk of death and need for intubation 1
- Low/falling pH combined with high APACHE II score indicates high risk of NIV failure 1
Criteria for Escalation to Invasive Mechanical Ventilation
Do not delay intubation when indicated - persisting with ineffective NIV increases mortality and risks cardiorespiratory arrest 1, 2. Immediate intubation is required for 1:
- Imminent respiratory arrest or gasping respiration
- Severe respiratory distress
- Persisting pH <7.15 or deteriorating pH despite optimized NIV
- Depressed consciousness (Glasgow Coma Score <8)
- Signs of low cardiac output
pH <7.25 is the threshold to consider IMV; pH <7.15 is an absolute indication for IMV (following initial resuscitation with controlled oxygen) 1.
Critical Pitfall to Avoid
Evidence from post-extubation respiratory failure demonstrates that delay in intubation caused by persisting with ineffective NIV increases mortality 1. The BTS/ICS guideline explicitly states that continued use of NIV when the patient is deteriorating, rather than escalating to IMV, increases mortality 1.
Weaning Strategies When Patient Stabilizes
If the patient stabilizes on NIV but cannot be immediately weaned, use a structured approach 1, 3:
Standard Weaning Protocol
NIV can be discontinued when pH normalizes, pCO₂ normalizes, and the patient shows general clinical improvement 1:
- Maximize NIV time in first 24 hours (depending on tolerance and complications) 1
- Taper daytime NIV over 2-3 days based on pCO₂ levels when self-ventilating 1
- Continue overnight NIV longer before final discontinuation 1
- Monitor transcutaneous pCO₂ on and off NIV to guide withdrawal speed 1
Two Equivalent Weaning Methods
Recent research shows neither method is superior - choose based on patient tolerance 3:
- Stepwise reduction of duration: 16h/day → 12h/day (including 6-8h nocturnal) → 6-8h/day → discontinue 3
- Stepwise reduction of pressure support: Reduce by 2-4 cm H₂O every 4-6h until IPAP <8 cm H₂O and EPAP <4 cm H₂O, then discontinue 3
Indications for Long-Term Home NIV
If the patient cannot be weaned after one week, consider referral for long-term home ventilation 1:
All patients with the following conditions who develop acute hypercapnic respiratory failure requiring NIV should be referred to a home ventilation service 1:
- Spinal cord lesions
- Neuromuscular diseases
- Chest wall deformity (scoliosis, thoracoplasty)
- Morbid obesity (BMI >30)
For COPD patients specifically, consider long-term home NIV if 1:
- Failure to wean from NIV after acute episode
- Recurrent AHRF (≥3 episodes in previous year) requiring NIV treatment
- Intolerance of supplementary oxygen due to CO₂ retention with symptomatic sleep disturbance
Pre-Discharge Assessment
Before discharge, all patients treated with NIV must undergo spirometry and arterial blood gas analysis on room air 1. If PaO₂ <7.3 kPa in COPD patients, repeat measurement after ≥3 weeks 1. If hypoxemia persists with hypercapnia on room air or significant PaCO₂ rise with supplemental oxygen, trial nocturnal NIV at home 1.
Special Consideration: Obesity Hypoventilation Syndrome
If the patient has OHS contributing to inability to wean 1:
- Fluid overload commonly contributes and is easily underestimated - may exceed 20L 1
- Forced diuresis is often indicated and may be critical 1
- Risk of NIV failure is greater; placement in HDU/ICU is recommended 1
- Many patients will require long-term domiciliary support (CPAP or NIV) 1
- Following AHRF episode, referral to home ventilation service is recommended 1