What are the indications for BiPAP (Bilevel Positive Airway Pressure) therapy in patients with respiratory failure or severe respiratory distress, particularly those with chronic obstructive pulmonary disease (COPD), pneumonia, or heart failure?

BiPAP Indications

BiPAP should be initiated in patients with acute respiratory distress when respiratory rate exceeds 25 breaths/min and SpO2 falls below 90%, particularly in those with hypercapnia (PaCO2 >50 mmHg) and acidosis (pH <7.35), as it reduces intubation rates and improves outcomes. 1

Primary Clinical Indications

Acute Heart Failure with Respiratory Distress

• Start BiPAP immediately in patients with acute heart failure presenting with respiratory rate >25 breaths/min and SpO2 <90% to decrease respiratory distress and reduce mechanical intubation rates. 1
• BiPAP provides inspiratory pressure support that improves minute ventilation and is particularly beneficial when acidosis and hypercapnia are present. 1
• Initiate as soon as possible after identifying respiratory distress—early application improves outcomes. 1

COPD Exacerbations with Hypercapnic Respiratory Failure

• BiPAP is highly effective in COPD patients with respiratory acidosis (pH 7.25-7.35) and elevated PaCO2 (>50 mmHg), achieving approximately 80% success in avoiding intubation. 2, 3
• The inspiratory pressure support improves minute ventilation, which is especially useful in hypercapnic patients. 1
• BiPAP offsets intrinsic PEEP, recruits collapsed alveoli, and improves ventilation-perfusion matching in obstructive lung disease. 2
• Patients with COPD history presenting with signs of fatigue or respiratory distress should preferentially receive BiPAP over CPAP alone. 1

Hypoxemic Respiratory Failure

• Consider BiPAP when high inspired oxygen concentrations (>60%) fail to maintain adequate oxygenation (SpO2 <90%). 2
• Applicable conditions include pneumonia, ARDS, chest wall trauma, and pulmonary fibrosis. 2

Chronic Alveolar Hypoventilation Syndromes

• BiPAP is indicated for neuromuscular diseases (ALS, muscular dystrophy), restrictive thoracic cage disorders (kyphoscoliosis), obesity hypoventilation syndrome, and central respiratory control disturbances. 2

Specific Physiologic Criteria for Initiation

Initiate BiPAP when ANY of the following are present:

• Respiratory rate >25 breaths/min with SpO2 <90% despite supplemental oxygen 1
• PaCO2 >50 mmHg (6.65 kPa) with pH <7.35 1
• Signs of respiratory muscle fatigue or increased work of breathing 1
• PaO2 <60 mmHg (8.0 kPa) despite oxygen therapy 1

Critical Contraindications

Absolute Contraindications (Proceed Directly to Intubation)

• Apnea or impending respiratory arrest 2
• Inability to protect airway 2
• Active vomiting 2
• Hemodynamic instability 2
• Facial trauma or inability to fit mask 2
• Massive hemoptysis during active bleeding 2
• Untreated pneumothorax 2

Relative Contraindications (Use with Extreme Caution)

• Recent myocardial infarction—BiPAP may be associated with higher MI rates compared to CPAP in acute heart failure. 2
• Severe hypoxemia despite high FiO2 2
• Altered mental status or inability to cooperate 2
• Hypotension—BiPAP can reduce blood pressure and should be used cautiously in hypotensive patients with regular blood pressure monitoring. 1

Initial Settings and Titration

Start with:

• IPAP: 14-20 cmH2O 2
• EPAP: 4-8 cmH2O 2
• Gradually titrate upward for comfort and efficacy 2
• Set backup rate for patients with poor respiratory drive 2

Mandatory Monitoring Protocol

Baseline Assessment

• Obtain arterial or venous blood gas for pH, PaCO2, and PaO2 before initiating BiPAP. 1, 2
• Continuous SpO2 monitoring is essential. 1, 2

Reassessment Timeline

• Repeat blood gas analysis at 1-2 hours after BiPAP initiation. 2
• Monitor blood pressure regularly throughout treatment given hypotensive risk. 1

BiPAP Failure Criteria (Proceed to Intubation)

Intubate if ANY of the following occur:

• No improvement or worsening after 1-2 hours of BiPAP trial 2
• Persistent or worsening respiratory acidosis with pH <7.25 2
• Worsening mental status or inability to cooperate 2
• Hemodynamic deterioration 2
• Inability to manage secretions 2
• Patient exhaustion despite BiPAP support 2
• PaO2 <60 mmHg, PaCO2 >50 mmHg, and pH <7.35 that cannot be managed non-invasively 1

Critical Success Factors

• Mask selection and fit are critical—poor fit leads to air leaks and treatment failure. 2
• Add heated humidification if patient complains of dryness or nasal congestion. 2
• Consider oronasal mask or chin strap if significant mouth leak occurs. 2
• Adjust pressure relief, rise time, and IPAP duration parameters for patient comfort and synchrony. 2

Important Caveats

COPD-Specific Considerations

• Measure blood pH and carbon dioxide tension (possibly including lactate) in patients with acute pulmonary edema or previous COPD history using venous blood. 1
• In COPD, hyperoxygenation may increase ventilation-perfusion mismatch, suppress ventilation, and lead to hypercapnia—monitor acid-base balance carefully. 1
• Target SpO2 of 88-92% in COPD patients to avoid CO2 retention while correcting hypoxemia. 4

Heart Failure-Specific Considerations

• On hospital arrival, patients with acute heart failure who still show signs of respiratory distress should continue with non-invasive ventilation, preferably BiPAP (PS-PEEP), in cases of acidosis and hypercapnia. 1
• BiPAP is particularly useful when combined with COPD history or signs of fatigue. 1
• BiPAP can be effective for heart failure patients with central sleep apnea unresponsive to CPAP. 5