Did my provider raise the continuous positive airway pressure (CPAP) pressure before my trip to 9,000 ft altitude, and how should I adjust my CPAP settings to control a high apnea‑hypopnea index at this altitude?

CPAP Pressure Adjustment at High Altitude

You should verify with your provider whether CPAP pressure was increased before your trip, and if not, request an immediate pressure increase of 2-3 cm H₂O above your sea-level setting to address the altitude-related increase in apnea-hypopnea index (AHI) from your usual <5 to >24 events/hour.

Understanding Your Current Situation

Your dramatic AHI increase from <5 to >24 events/hour at 9,000 feet represents a clinically significant worsening that requires intervention, even though you're feeling somewhat rested 1, 2. This elevation in respiratory events is likely multifactorial:

• Altitude physiology: At 9,000 feet, the reduced atmospheric pressure and lower oxygen tension can destabilize upper airway mechanics and increase the frequency of obstructive events, even in patients with previously well-controlled OSA 1, 2
• Mouth breathing: Your suspicion about mouth breathing is valid—this creates an air leak that reduces effective CPAP pressure delivery and can trigger more respiratory events 3
• Acclimatization period: The first several days at altitude are typically the most challenging, which aligns with your experience of improving sleep quality by night 3-4 1

Immediate Action Steps

1. Confirm Pressure Adjustment Status

• Contact your provider immediately to verify whether CPAP pressure was increased prior to your trip 1, 2
• If no adjustment was made, this explains your elevated AHI and requires correction 2

2. Pressure Increase Protocol

• If your provider did NOT increase pressure: Request an increase of 2-3 cm H₂O above your sea-level therapeutic pressure 1, 2
• The American Academy of Sleep Medicine recommends pressure adjustments in increments of at least 1 cm H₂O, with the goal of eliminating obstructive events 3, 1, 2
• Your current AHI of >24 events/hour indicates inadequate pressure for altitude conditions 2

3. Address Mouth Breathing

• If mouth breathing is occurring: Switch to a full-face (oronasal) mask or add a chin strap to your current nasal mask setup 3
• Mouth leak significantly reduces effective CPAP delivery and is a common cause of treatment failure at any altitude 3
• This intervention alone may substantially reduce your AHI without requiring further pressure increases 3

Ongoing Management During Your Trip

Monitor and Adjust

• Continue checking your CPAP machine's event data daily 1, 2
• If AHI remains >5 events/hour after implementing the above changes, further pressure increases of 1 cm H₂O may be needed 1, 2
• Wait at least one full night between pressure adjustments to assess response 3, 1

Comfort Considerations

• If increased pressure feels uncomfortable and disrupts your sleep, reduce pressure to a level that allows you to sleep, then attempt gradual increases over subsequent nights 3, 1, 2
• Patient tolerance supersedes algorithmic targets—it's better to use slightly lower pressure consistently than optimal pressure intermittently 1, 2
• Consider using your machine's pressure ramp feature if available, which starts at lower pressure and gradually increases to therapeutic level as you fall asleep 3

Maximum Pressure Limits

• The American Academy of Sleep Medicine recommends maximum CPAP should not exceed 20 cm H₂O for adults 1, 4
• If obstructive events persist at 15 cm H₂O of CPAP, switching to BiPAP should be considered 1, 4, 2

Common Pitfalls to Avoid

• Do not ignore elevated AHI: Even if you feel rested, an AHI >24 events/hour indicates inadequate treatment and carries cardiovascular and neurocognitive risks 2, 5
• Do not make pressure changes >2.5 cm H₂O at once: Large jumps in pressure reduce tolerance and compliance 3, 1
• Do not assume acclimatization alone will resolve the problem: While some improvement may occur over 3-7 days at altitude, your AHI suggests active intervention is needed 1, 2

Follow-Up After Return to Sea Level

• Plan to return to your original sea-level CPAP pressure once you descend from altitude 1, 2
• Schedule follow-up with your provider within 2-4 weeks of returning home to review CPAP data from the entire trip 5
• If problems persist after returning to sea level, formal attended CPAP retitration may be indicated 5, 6, 7