Indications for BiPAP Therapy
Primary Indications
BiPAP should be initiated in patients with acute respiratory distress (respiratory rate >25 breaths/min, SpO2 <90%) to decrease respiratory work, improve gas exchange, and reduce the need for endotracheal intubation. 1
Acute Hypercapnic Respiratory Failure
- COPD exacerbations with respiratory acidosis represent the strongest indication for BiPAP, with success rates of approximately 80% (20 of 25 patients) in avoiding intubation 2
- BiPAP is particularly effective when pH is between 7.25-7.35 with elevated PaCO2 (>50 mmHg) 1, 3
- The therapy offsets intrinsic PEEP, recruits collapsed alveoli, and improves ventilation-perfusion matching in obstructive lung disease 3
Acute Cardiogenic Pulmonary Edema
- Non-invasive positive pressure ventilation (BiPAP or CPAP) should be considered in acute heart failure patients with respiratory distress to reduce intubation rates 1, 4
- Important caveat: BiPAP may be associated with higher myocardial infarction rates compared to CPAP in acute heart failure syndrome, so use with caution and monitor closely 3, 4
- BiPAP can reduce blood pressure and should be used cautiously in hypotensive patients 1, 4
Hypoxemic Respiratory Failure
- BiPAP can be used when high inspired oxygen concentrations (>60%) fail to maintain adequate oxygenation (SpO2 <90%) 1
- Success rates are lower in hypoxemic failure (15 of 31 patients, 48%) compared to hypercapnic failure, with a 2.6-fold higher risk of BiPAP failure 2
- Conditions include pneumonia, ARDS, chest wall trauma, and pulmonary fibrosis 1
Post-Extubation Respiratory Failure
- BiPAP is highly effective (80% success rate) in patients developing respiratory failure within 48 hours of extubation 2, 5
- This application can temporize patients and avoid reintubation 2
Chronic Alveolar Hypoventilation Syndromes
- Neuromuscular diseases (ALS, muscular dystrophy) 1
- Restrictive thoracic cage disorders (kyphoscoliosis) 1
- Obesity hypoventilation syndrome 1
- Central respiratory control disturbances 1
Severe Asthma with Acute Respiratory Failure
- BiPAP may offer short-term support in alert patients with adequate spontaneous respiratory effort, potentially delaying or eliminating need for intubation 3
Absolute Contraindications
- Apnea or impending respiratory arrest - requires immediate intubation 3
- Inability to protect airway 4
- Active vomiting 4
- Hemodynamic instability 4
- Facial trauma or inability to fit mask 3, 4
- Massive hemoptysis during active bleeding 3
- Untreated pneumothorax 3
Relative Contraindications (Use with Extreme Caution)
- Recent myocardial infarction 3
- Severe hypoxemia despite high FiO2 3
- Altered mental status or inability to cooperate (requires patient cooperation for success) 4
Monitoring Requirements and Failure Criteria
Initial Assessment
- Obtain baseline arterial or venous blood gas for pH, PaCO2, and PaO2 4
- Monitor SpO2 continuously 1
- Reassess at 1-2 hours with repeat blood gas analysis 3, 4
Criteria for BiPAP Failure (Proceed to Intubation)
- No improvement or worsening after 1-2 hours of BiPAP trial 3, 4
- Persistent or worsening respiratory acidosis with pH <7.25 3, 4
- Worsening mental status or inability to cooperate 3
- Hemodynamic deterioration 3
- Inability to manage secretions 3
- Patient exhaustion despite BiPAP support 3
Optimal Initial Settings
- IPAP: 14-20 cmH2O (provides inspiratory assistance) 3
- EPAP: 4-8 cmH2O (maintains airway patency) 3
- Titrate pressures upward gradually for comfort and efficacy 1
- Ensure backup rate is set for patients with poor respiratory drive 4
Expected Physiological Response
- In hypercapnic failure: Increased pH and reduced PaCO2 within 1-2 hours 2
- In hypoxemic failure: Increased PaO2/FiO2 ratio 2
- Decreased respiratory rate 2, 5
- Typical duration of BiPAP dependency in successful cases: approximately 35 hours 2
Critical Success Factors
- Mask selection and fit are critical - poor fit leads to air leaks and treatment failure 3
- Add heated humidification if patient complains of dryness or nasal congestion 1
- Consider oronasal mask or chin strap if significant mouth leak causes arousals 1
- Adjust pressure relief, rise time, and IPAP duration parameters for patient comfort and synchrony 1