For my suspected upper airway resistance syndrome, should I set the BiPAP to VAuto (auto‑BiPAP) mode with EPAP 4 cm H₂O and an IPAP range of 4–8 cm H₂O to achieve a pressure support of 4 cm H₂O?

BiPAP Settings for Upper Airway Resistance Syndrome

No, your proposed settings are incorrect and potentially inadequate. For suspected upper airway resistance syndrome (UARS), you should not use VAuto mode with those parameters—standard BiPAP titration should start with IPAP 8 cm H₂O and EPAP 4 cm H₂O in spontaneous mode, then titrate upward based on elimination of RERAs, flow limitation, and snoring 1, 2.

Why Your Proposed Settings Are Problematic

Your suggestion of "EPAP 4 cm H₂O with IPAP range 4–8 cm H₂O" creates several critical issues:

• An IPAP of 4 cm H₂O equals your EPAP of 4 cm H₂O, resulting in zero pressure support, which provides no therapeutic benefit whatsoever 1, 3
• The minimum pressure support (PS) must be 4 cm H₂O (the difference between IPAP and EPAP), not an IPAP value of 4 cm H₂O 1, 3
• Even an IPAP maximum of 8 cm H₂O only provides 4 cm H₂O of pressure support, which is the bare minimum and likely insufficient for UARS where residual upper airway resistance causes repetitive arousals 1

Correct Initial Settings for UARS

Start with these parameters 1, 2:

• IPAP: 8 cm H₂O (not 4–8 range)
• EPAP: 4 cm H₂O
• Pressure Support: 4 cm H₂O minimum (IPAP minus EPAP = 8 - 4 = 4)
• Mode: Spontaneous (S mode), not VAuto initially 2

Titration Algorithm for UARS

UARS requires aggressive titration to eliminate flow limitation and RERAs, not just apneas 1:

• Increase IPAP by 1–2 cm H₂O every 5 minutes if you observe 1, 2:

  • ≥5 RERAs (respiratory effort-related arousals) 1, 2
  • ≥3 minutes of loud/unambiguous snoring 1
  • Persistent inspiratory flow limitation on the flow waveform 1

• For obstructive apneas, increase both IPAP and EPAP together if ≥2 apneas occur 1, 2

• Maximum IPAP should be 30 cm H₂O for adults ≥12 years 1, 3

• Maximum pressure support can reach 10 cm H₂O for OSA/UARS (though up to 20 cm H₂O is allowed for hypoventilation syndromes) 1, 3

Special Considerations for UARS

Upper airway resistance can persist even after eliminating obvious apneas, leading to continued arousals and poor sleep quality 1:

• "Exploration" of pressure above the level that eliminates obvious events may be needed, increasing by 2 cm H₂O but not exceeding 5 cm H₂O above the baseline effective pressure 1
• This addresses residual high airway resistance that can be four times normal despite apparent control of breathing events 1
• Normalization of inspiratory flow limitation on the flow curve is the goal, not just AHI reduction 1

When to Consider VAuto Mode

VAuto (auto-BiPAP) is not the first-line approach for initial titration 1:

• Manual attended titration remains the gold standard for determining optimal pressures 1
• VAuto may be considered after establishing a baseline pressure range through manual titration 1
• If you do use VAuto, set the EPAP at the minimum needed to prevent obstructive events (typically 4–6 cm H₂O), and allow IPAP to auto-adjust within a range that provides adequate pressure support 1

Common Pitfalls to Avoid

• Do not confuse IPAP values with pressure support values—they are not the same 1, 3
• Do not undertitrate in UARS—these patients need sufficient pressure to normalize flow limitation, not just eliminate apneas 1
• If the patient complains pressure is too high during titration, restart at a lower comfortable pressure rather than abandoning therapy 1
• Monitor for treatment-emergent central apneas; if they develop, consider decreasing IPAP or switching to spontaneous-timed (ST) mode with backup rate 1, 2