What are the indications for BiPAP (Bilevel Positive Airway Pressure) in patients with severe Chronic Obstructive Pulmonary Disease (COPD)?

BiPAP Indications in COPD

BiPAP should be initiated in COPD patients with acute hypercapnic respiratory failure when pH is less than 7.35 with rising PaCO2 despite optimal medical therapy and controlled oxygen. 1

Primary Indications for Acute Exacerbation

BiPAP is indicated when patients meet specific blood gas criteria despite maximal medical management:

• pH <7.35 with hypercapnia (PaCO2 >45 mmHg or 6 kPa) 1
• Respiratory rate >24 breaths/min despite bronchodilators and corticosteroids 1
• Rising PaCO2 on controlled oxygen therapy 1

The critical threshold is a pH <7.26 with rising PaCO2 that fails to respond to supportive treatment and controlled oxygen therapy 2. At this point, ventilatory support becomes essential to prevent further deterioration.

Initial BiPAP Settings

Start with conservative settings and titrate based on response:

• IPAP: 10-15 cmH2O 1
• EPAP: 4-5 cmH2O 1
• Target SpO2: 88-92% (not higher, to avoid CO2 retention) 1

Absolute Contraindications

BiPAP should not be used in the following situations:

• Respiratory arrest 1
• Cardiovascular instability (hypotension, arrhythmias, acute MI) 1
• Impaired mental status or somnolence 1
• Inability to cooperate with the mask 1
• Confused patients 2
• Large volumes of secretions that cannot be cleared 2

Monitoring and Response Assessment

Reassess arterial blood gas within 30-60 minutes of initiating BiPAP 1. This is the critical decision point:

• If pH improves: Continue BiPAP and reassess regularly 1
• If pH continues to decline: Prepare for intubation and invasive mechanical ventilation 2, 1

The pH measured after 45 minutes of BiPAP with optimal settings is highly predictive of success—patients who respond typically have pH ≥7.35, while those who fail average pH 7.28 3.

Concurrent Medical Management

BiPAP is an adjunct, not a replacement for aggressive medical therapy. Continue:

• Nebulized bronchodilators: Salbutamol 2.5-5 mg plus ipratropium 500 μg 1
• Systemic corticosteroids: 0.4-0.6 mg/kg prednisone equivalent daily (or 30 mg prednisolone, or 100 mg hydrocortisone IV if oral route unavailable) 2, 1
• Antibiotics if infection is suspected 2
• Controlled oxygen therapy targeting SpO2 88-92% 1

Setting Requirements

BiPAP requires the same level of supervision as conventional mechanical ventilation 1. This typically means:

• High-dependency unit or ICU setting 2
• Continuous monitoring capability 1
• Staff trained in BiPAP management 2

Common Pitfalls to Avoid

Do not administer high-flow oxygen without ABG confirmation in COPD patients, as this can precipitate acute respiratory failure by suppressing hypoxic drive 1. Always use controlled oxygen therapy with target SpO2 88-92%.

Do not delay intubation if the patient is deteriorating despite BiPAP—the decision to intubate should be made by a senior clinician with knowledge of the patient's premorbid state and wishes 2.

Do not use BiPAP in patients with copious secretions—they are less likely to respond and may aspirate 2.

Chronic Home BiPAP Use

For stable COPD patients, home BiPAP may be considered in selected patients with pronounced daytime hypercapnia and recent hospitalization, though evidence is contradictory regarding effectiveness 2. This is distinct from acute BiPAP use and requires different patient selection criteria.

In patients with both COPD and obstructive sleep apnea, continuous positive airway pressure (CPAP, not BiPAP) is indicated and improves survival 2.