When should a patient be considered for BiPAP (Bilevel Positive Airway Pressure) therapy?

BiPAP Indications in Clinical Practice

Patients should be placed on BiPAP when they have acute or acute-on-chronic respiratory acidosis (pH ≤7.35) due to COPD exacerbation, or when they have respiratory failure requiring ventilatory support but are not immediately deteriorating to the point of requiring intubation. 1

Primary Indications for BiPAP

BiPAP (Bilevel Positive Airway Pressure) is indicated in several specific clinical scenarios:

COPD Exacerbation

• Strong indication: pH ≤7.35, PaCO2 >45 mmHg, and respiratory rate >20-24 breaths/min despite standard medical therapy 1
• BiPAP has been shown to decrease mortality (relative risk 0.63) and reduce need for intubation (relative risk 0.41) in this population 1
• No lower pH limit exists below which BiPAP should not be tried, but lower pH indicates higher risk of failure requiring close monitoring 1

Cardiogenic Pulmonary Edema

• BiPAP can improve respiratory mechanics and facilitate left ventricular work by decreasing left ventricular afterload 1
• Should be considered in patients with respiratory distress from pulmonary edema who remain hypoxemic despite standard therapy 1, 2

Type 2 Respiratory Failure

• Particularly indicated in patients with chronic respiratory conditions who develop acute-on-chronic respiratory failure 1
• NHS guidelines consider BiPAP appropriate for patients with type 2 respiratory failure (e.g., COPD) 1

Other Indications

• Neuromuscular disorders with respiratory compromise (e.g., myasthenic crisis without hypercapnia) 3
• End-stage cystic fibrosis patients awaiting lung transplantation 4
• Sleep-disordered breathing and nighttime hypoventilation in patients with neuromuscular disorders 1

Contraindications for BiPAP

BiPAP should NOT be used in patients with:

• Respiratory arrest 1
• Cardiovascular instability (hypotension, arrhythmias, myocardial infarction) 1
• Impaired mental status, somnolence, inability to cooperate 1
• Copious/viscous secretions with high aspiration risk 1
• Recent facial or gastro-esophageal surgery 1
• Craniofacial trauma or fixed nasopharyngeal abnormality 1
• Pneumothorax (BiPAP should be discontinued in patients with pneumothorax) 1

Monitoring and Assessment

When initiating BiPAP:

1. Close monitoring is essential - patient condition should be assessed within 1-2 hours after starting BiPAP 1

2. Parameters to monitor:

   • Arterial blood gases (pH, PaCO2, PaO2)
   • Respiratory rate
   • Work of breathing
   • Mental status
   • Oxygen saturation (target 90-96%, or 88-92% in patients with chronic type 2 respiratory failure) 1

3. Failure criteria - consider intubation if:

   • Worsening of ABGs and/or pH within 1-2 hours
   • Lack of improvement in ABGs and/or pH after 4 hours
   • Development of contraindications
   • Patient intolerance 1

BiPAP Settings

Initial settings typically include:

• IPAP (inspiratory positive airway pressure): 8-10 cmH2O, can be increased to 12-18 cmH2O as needed
• EPAP (expiratory positive airway pressure): 3-4 cmH2O, can be increased to 7-8 cmH2O as needed 1, 4

Settings should be titrated based on:

• Patient comfort
• Work of breathing
• Oxygen saturation
• Arterial blood gases

Common Pitfalls to Avoid

1. Delayed intubation - BiPAP should not delay necessary intubation in rapidly deteriorating patients 1
2. Inadequate monitoring - Patients on BiPAP require close observation, especially in the first few hours
3. Inappropriate patient selection - Using BiPAP in patients with contraindications increases risks
4. Mask-related complications - Eye irritation, skin ulceration, and gastric distention can occur; proper mask fitting is essential 1
5. Inadequate pressure settings - Insufficient pressure support may fail to relieve respiratory distress

Special Considerations

• COVID-19 patients: Close monitoring is particularly important, with evaluation within 1-2 hours of BiPAP initiation 1
• Neuromuscular disorders: Presence of hypercapnia (PaCO2 >50 mmHg) at onset may predict BiPAP failure 3
• Cystic fibrosis: BiPAP may provide respiratory stability for end-stage patients awaiting lung transplantation 4
• Morbid obesity: BiPAP may improve oxygenation through alveolar recruitment 5

By following these guidelines and carefully selecting appropriate patients, BiPAP can effectively prevent the need for intubation, reduce mortality, and improve outcomes in various respiratory conditions.