What are the initial settings for non-invasive ventilation (NIV)?

Initial Settings for Non-Invasive Ventilation (NIV)

For patients requiring non-invasive ventilation in acute respiratory failure, the initial settings should include IPAP of 10-12 cmH₂O and EPAP of 4-5 cmH₂O, with oxygen titrated to maintain SpO₂ 85-90% in COPD patients. 1

Equipment Selection

Bi-level pressure support ventilators are recommended for acute NIV services due to their simplicity, cost-effectiveness, and flexibility 2, 1. These ventilators have been used in the majority of randomized controlled trials showing improved outcomes in acute hypercapnic respiratory failure.

Essential ventilator features:

• Pressure control capability (at least 30 cmH₂O)
• Support for inspiratory flows of at least 60 L/min
• Assist-control and bi-level pressure support modes
• Rate capability of at least 40 breaths/min
• Sensitive flow triggers
• Disconnection alarm 2

Initial Settings Algorithm

1. Mode Selection

• Bi-level pressure support (most commonly used for acute respiratory failure)
• Assist-control mode for patients with minimal respiratory effort

2. Pressure Settings

• IPAP (Inspiratory Positive Airway Pressure): 10-12 cmH₂O initially 1
• EPAP (Expiratory Positive Airway Pressure): 4-5 cmH₂O initially 1, 3
• Pressure support (difference between IPAP and EPAP) should be at least 5-7 cmH₂O

3. Respiratory Rate

• Set backup rate at 12-15 breaths/minute (opinions vary between low 8-10 or high 18-20 breaths/min) 3

4. Oxygen Supplementation

• Titrate FiO₂ to maintain SpO₂ 85-90% in COPD patients 2, 1
• Add oxygen if SpO₂ <85% 2

5. Inspiratory Time/Cycling

• For bi-level devices, start with default settings
• For volume-controlled ventilators, set inspiratory time to achieve I:E ratio of approximately 1:2 to 1:3

Patient Interface Selection

• Select appropriate mask size to fit the patient
• Facial masks are commonly used for acute settings 4
• Hold mask in place initially to familiarize the patient before securing with straps 2

Monitoring and Adjustment Protocol

Initial Assessment (first 30-60 minutes):

1. Monitor patient comfort, conscious level, chest wall motion
2. Assess accessory muscle recruitment and coordination with ventilator
3. Monitor respiratory rate, heart rate, and SpO₂ continuously 2, 1

Early Adjustment (1-2 hours):

1. Check arterial blood gases after 1-2 hours of NIV 2, 1
2. If patient is uncomfortable or fighting the ventilator:
   • Check for mask leaks
   • Adjust trigger sensitivity
   • Consider increasing or decreasing IPAP based on patient comfort

Pressure Titration Algorithm:

• If PaCO₂ remains elevated:

  • Increase IPAP by 2-5 cmH₂O (up to 20-25 cmH₂O) 3
  • Consider increasing respiratory rate

• If oxygenation remains poor:

  • Increase FiO₂
  • Consider increasing EPAP by 1-2 cmH₂O (caution in COPD) 2

• If patient is uncomfortable:

  • Check mask fit and adjust to minimize leaks
  • Consider adjusting rise time if available
  • Ensure synchrony between patient and ventilator

Common Pitfalls to Avoid

1. Starting with pressures too high - can cause discomfort, mask leaks, and patient intolerance
2. Inadequate monitoring - failure to check blood gases after 1-2 hours may miss deterioration
3. Poor mask fit - leads to leaks and reduced effectiveness
4. Insufficient pressure support - inspiratory pressures must be in the 20-25 cmH₂O range to meaningfully reduce PaCO₂ in severe cases 3
5. Failure to establish a backup plan - always decide about management if NIV fails before starting 2, 1

Special Considerations by Condition

COPD Exacerbation

• Target SpO₂ 85-90% to avoid CO₂ retention
• EPAP helps overcome intrinsic PEEP 2

Cardiogenic Pulmonary Edema

• Higher EPAP (8-10 cmH₂O) may be beneficial
• CPAP at 10 cmH₂O is often sufficient without bi-level support 4

Neuromuscular Disease

• May require higher backup rate due to weak respiratory effort
• Timed mode may be necessary if patient cannot trigger breaths 2

Remember that NIV settings should be reassessed and adjusted based on patient response, with arterial blood gas analysis after 4-6 hours if the earlier sample showed little improvement 2, 1.