What is the equivalent of BiPAP (Bilevel Positive Airway Pressure) settings on a NIV (Non-Invasive Ventilation) machine that does not have explicit EPAP (Expiratory Positive Airway Pressure) and IPAP (Inspiratory Positive Airway Pressure) settings for a patient with a history of respiratory conditions such as COPD (Chronic Obstructive Pulmonary Disease) or sleep apnea?

NIV Machine Settings Without EPAP/IPAP Labels

If your NIV machine does not explicitly label EPAP and IPAP, look for settings called "PEEP" (equivalent to EPAP) and "Pressure Support" or "Inspiratory Pressure" (which when added to PEEP equals IPAP). 1, 2

Understanding the Terminology Equivalents

EPAP Equivalents

• PEEP (Positive End-Expiratory Pressure) is the direct equivalent of EPAP 1, 2
• Some machines may label this as "baseline pressure" or "expiratory pressure" 1
• EPAP/PEEP serves to offset intrinsic PEEP in COPD patients, recruit underventilated lung, and vent exhaled gas through the exhaust port 1, 2

IPAP Equivalents

• IPAP = PEEP + Pressure Support 3, 2
• If your machine shows "Pressure Support" and "PEEP" separately, add these values together to get the equivalent IPAP 3, 2
• For example: PEEP 5 cmH₂O + Pressure Support 10 cmH₂O = IPAP 15 cmH₂O 2
• Some machines may label inspiratory pressure as "inspiratory positive airway pressure" or simply "inspiratory pressure" 1, 4

Recommended Initial Settings

For COPD or Acute Respiratory Failure

• PEEP (EPAP equivalent): Start at 4-8 cmH₂O 2
• Pressure Support: Start at 5-10 cmH₂O (to achieve total inspiratory pressure of 10-15 cmH₂O) 3, 2
• Minimum pressure difference: Maintain at least 5 cmH₂O between inspiratory and expiratory pressures 3, 2
• Backup rate: 10-14 breaths/min if using Spontaneous/Timed mode 2

For Hypoxemic Respiratory Failure

• CPAP mode: Start at 10 cmH₂O with FiO₂ 0.6 5
• Escalation if needed: Increase to 12-15 cmH₂O with FiO₂ 0.6-1.0 5
• Maximum CPAP: Can be increased up to 15-20 cmH₂O if escalation is needed 5

Alternative Machine Modes

If Only CPAP Mode Available

• CPAP provides a single continuous pressure level throughout the respiratory cycle 1
• CPAP is indicated primarily for hypoxemic respiratory failure, not for ventilatory support in type 2 respiratory failure 5
• CPAP alone cannot provide ventilatory assistance for patients with poor respiratory drive or hypercapnia 5

If Pressure Control Mode Available

• Set Peak Inspiratory Pressure (PIP) as your IPAP equivalent 6
• Set PEEP as your EPAP equivalent 6
• This functions similarly to bi-level pressure support 6

Critical Pitfalls to Avoid

Inadequate Pressure Support

• Ensure the difference between inspiratory and expiratory pressure is at least 5 cmH₂O 3, 2
• Insufficient pressure support will not adequately reduce work of breathing 7

Rebreathing Risk

• EPAP/PEEP levels of 3-5 cmH₂O may not completely eliminate rebreathing, especially with tachypnea 1, 4
• If the patient develops worsening hypercapnia despite NIV, check for exhaust port occlusion and consider increasing EPAP 1, 3

Excessive Expiratory Time in COPD

• For patients with obstructive disease, use shorter inspiratory time (approximately 30% of cycle time) to allow adequate exhalation 3
• Target I:E ratio of approximately 1:2 to prevent air trapping and auto-PEEP 2

Flow Requirements

• The ventilator must be capable of delivering at least 60 L/min flow, as distressed COPD patients may have peak inspiratory flows exceeding this threshold 2
• Low-flow CPAP generators designed for sleep apnea are inadequate for acute respiratory failure 1

Monitoring and Titration

Target Oxygen Saturation

• COPD patients: SpO₂ 88-92% to avoid worsening hypercapnia 2
• General acute respiratory failure: SpO₂ above 90% but no higher than 96% 5
• Pregnant patients: SpO₂ 92-95% 5

Timing of Reassessment

• Recheck arterial blood gases after 30-60 minutes of NIV 2
• Most patients showing positive response will demonstrate improvement in pH, PaCO₂, and PaO₂ within 1-4 hours 2
• Consider intubation if no improvement after 4 hours or worsening within 1-2 hours 2