What are the initial settings for Non-Invasive Ventilation (NIV)?

Initial NIV Settings

For acute hypercapnic respiratory failure due to COPD, start bi-level pressure support with IPAP 10-15 cmH₂O and EPAP 4-5 cmH₂O, then titrate upward based on patient tolerance and arterial blood gas response at 1-2 hours. 1

Bi-Level Pressure Support (BiPAP) Settings - Primary Mode

Starting Parameters for COPD/Hypercapnic Respiratory Failure:

• IPAP (Inspiratory Positive Airway Pressure): Begin at 10-15 cmH₂O 1
• EPAP (Expiratory Positive Airway Pressure): Begin at 4-5 cmH₂O 1
• Backup respiratory rate: Set to match patient's spontaneous rate (typically 12-16 breaths/min for COPD) 1
• Inspiratory time: 0.8-1.2 seconds 1

Rationale for These Settings:

• EPAP at 4-5 cmH₂O overcomes intrinsic PEEP in COPD patients, which can be 10-15 cmH₂O but higher EPAP levels (>5 cmH₂O) are rarely tolerated 1
• The pressure differential (IPAP minus EPAP) determines tidal volume delivery and should start conservatively to ensure patient tolerance 1
• Bi-level pressure support ventilators are simpler, cheaper, and more flexible than volume-controlled ventilators and have been used in the majority of randomized controlled trials 1

CPAP Settings - For Cardiogenic Pulmonary Edema

Starting Parameters:

• PEEP: 5-7.5 cmH₂O, titrate up to 10 cmH₂O based on clinical response 2
• FiO₂: Start at 0.40 (40%) 2
• Duration: Typically 30 minutes per hour until dyspnea and oxygen saturation remain improved without CPAP 2

When to Use CPAP vs BiPAP:

• CPAP is first-line for acute cardiogenic pulmonary edema unresponsive to conventional oxygen therapy 1, 2
• BiPAP may be considered for heart failure patients with fatigue and hypercapnia, though no clear advantage over CPAP has been demonstrated in comparative trials 3, 4

Oxygen Supplementation

• Add supplemental oxygen if SpO₂ <85% after initiating NIV 1, 2
• Target SpO₂ 88-92% in hypercapnic patients to avoid worsening CO₂ retention 5, 6
• Target SpO₂ 94-98% in most other patients without hypercapnia risk 5
• Oxygen should be fed proximal to the mask on most bi-level ventilators that entrain room air 1

Titration Algorithm

Initial Assessment (First Few Minutes):

1. Hold the mask in place manually for the first few minutes to familiarize the patient 1
2. Reassess patient comfort, respiratory rate, and SpO₂ 1
3. Adjust settings if patient appears uncomfortable or asynchronous with ventilator 1

Early Reassessment (1-2 Hours):

• Perform arterial blood gas analysis at 1-2 hours to assess pH, PaCO₂, and PaO₂ 1, 2
• If PaCO₂ and pH have deteriorated after 1-2 hours on optimal settings, institute alternative management plan (consider intubation) 1, 2
• If no improvement but no deterioration, continue NIV and reassess with repeat ABG at 4-6 hours 1
• If no improvement in PaCO₂ and pH by 4-6 hours, institute alternative management plan 1

Upward Titration Strategy:

• Increase IPAP by 2-3 cmH₂O increments if tidal volume is inadequate or PaCO₂ remains elevated 1, 3
• Maximum IPAP typically 20-25 cmH₂O for patient tolerance 3
• EPAP rarely needs to exceed 5 cmH₂O in COPD due to poor tolerance 1
• For CPAP in heart failure, titrate PEEP up to 10 cmH₂O based on dyspnea and oxygenation response 2

Critical Monitoring Parameters

Continuous Monitoring:

• Pulse oximetry should be attached before and throughout NIV 1, 2
• Respiratory rate, work of breathing, and patient-ventilator synchrony 5, 7
• Blood pressure, especially in heart failure patients, as NIV can further reduce blood pressure 2

Indications for Escalation to Intubation:

• Worsening respiratory acidosis (pH <7.30) despite NIV 5
• Persistent hypoxemia (SpO₂ <85%) on maximum NIV settings 5
• Increasing work of breathing or respiratory rate >35 breaths/min 5
• Altered mental status or inability to protect airway 5
• Hemodynamic instability 5

Common Pitfalls to Avoid

• Do not make ventilator changes without arterial blood gas data after the initial 1-2 hour assessment, as blind adjustments may worsen outcomes 6
• Avoid excessive EPAP (>5 cmH₂O) in COPD patients as it may worsen hyperinflation and is poorly tolerated 1
• Do not maintain FiO₂ at 1.0 longer than necessary as hyperoxia may be harmful 6
• Ensure minimal mask leak as excessive leakage causes patient-ventilator asynchrony and NIV failure 1, 3, 7
• Select an appropriately sized mask and secure it properly after the initial familiarization period 1, 2
• Instruct the patient how to remove the mask and summon help before leaving them unattended 1, 2

Patient Selection Considerations

Ideal Candidates:

• COPD with respiratory acidosis (PaCO₂ >45 mmHg, pH 7.25-7.35) after maximal medical treatment 1
• Acute cardiogenic pulmonary edema with respiratory distress (respiratory rate >25 breaths/min, SpO₂ <90%) 2
• Chest wall deformity, neuromuscular disorder, or decompensated obstructive sleep apnea 1

Patients Requiring ICU/HDU Management:

• pH <7.25 or H⁺ >56 nmol/L respond less well and should be managed in higher acuity settings 1
• Severe life-threatening hypoxemia is more appropriately managed by tracheal intubation 1