What are the guidelines for setting Continuous Positive Airway Pressure (CPAP) machine settings?

CPAP Settings Guidelines

Start CPAP at 4 cm H₂O for most adults, but use 8-10 cm H₂O for obese patients (BMI >30), then increase by 1 cm H₂O every 5 minutes until respiratory events are eliminated, with a maximum of 20 cm H₂O for adults. 1, 2

Initial Pressure Settings

Standard Starting Pressure

• Begin at 4 cm H₂O for all pediatric and adult patients as the baseline minimum 1
• For patients with elevated BMI or retitration studies, start higher at 8-10 cm H₂O due to increased upper airway resistance 1, 2
• There is insufficient evidence to precisely predict starting pressure, though BMI correlates with required pressure (ρ = 0.32, p <0.001) 1

Maximum Pressure Limits

• Adults (≥12 years): 20 cm H₂O maximum 1
• Children (<12 years): 15 cm H₂O maximum 1

Titration Protocol

Pressure Adjustment Algorithm

• Increase CPAP by at least 1 cm H₂O with intervals no shorter than 5 minutes 1
• Pressure increments can range from 1-2.5 cm H₂O, but there is insufficient data to recommend increases >2.5 cm H₂O 1
• For split-night studies or obese patients, consider larger increments (2-2.5 cm H₂O) to reach effective pressure more quickly 1, 2

Indications to Increase Pressure

Increase CPAP when you observe:

• ≥2 obstructive apneas in adults (≥12 years) 1
• ≥1 obstructive apnea in children (<12 years) 1
• ≥1 hypopnea 1
• ≥3 respiratory effort-related arousals (RERAs) 1
• ≥3 minutes of loud/unambiguous snoring in adults 1
• ≥1 minute of loud/unambiguous snoring in children 1

Pressure Exploration

• Once respiratory events are controlled, you may explore pressure up to 5 cm H₂O above the control level to reduce residual upper airway resistance 1
• This exploration addresses the fact that airway resistance can remain 4 times normal despite eliminating apneas/hypopneas, causing repetitive arousals 1
• Do not exceed 5 cm H₂O above control pressure 1, 3

Transitioning to BiPAP

When to Switch from CPAP to BiPAP

• If patient is uncomfortable or intolerant of high CPAP pressures 1
• If obstructive events persist at 15 cm H₂O CPAP (applies to both adults and children) 1

BiPAP Initial Settings

• Start with IPAP 8 cm H₂O / EPAP 4 cm H₂O 1, 3, 2
• For obese patients, consider starting EPAP at 4-5 cm H₂O 2

BiPAP Titration Parameters

• Minimum IPAP-EPAP differential: 4 cm H₂O 1, 2
• Maximum IPAP-EPAP differential: 10 cm H₂O 1, 2
• Maximum IPAP for children (<12 years): 20 cm H₂O 1
• Maximum IPAP for adults (≥12 years): 30 cm H₂O 1, 2
• Increase IPAP and/or EPAP by at least 1 cm H₂O every 5 minutes depending on event type 1

Patient Tolerance Management

Pressure Intolerance Protocol

• If patient awakens complaining pressure is too high, immediately reduce to a comfortable level that allows return to sleep, then resume gradual titration 1
• This applies to both CPAP and BiPAP titration 1
• Consider switching to BiPAP if patient cannot tolerate necessary CPAP levels 1, 3

Special Populations

Obese Patients (High BMI)

• Start at 8-10 cm H₂O rather than 4 cm H₂O 2
• Use pressure increments of 2-2.5 cm H₂O for faster titration 2
• Consider head elevation at 30 degrees during sleep to reduce upper airway obstruction 2
• EPAP helps offset intrinsic PEEP common in patients with airflow limitation 2

Split-Night Studies

• Use identical titration algorithm as full-night studies 1
• Consider larger increments (2-2.5 cm H₂O) given shorter titration duration 1
• Be aware that pressures may be lower for mild-to-moderate OSA patients who don't manifest maximal severity in the first portion of night 1

Common Pitfalls to Avoid

• Starting too low in obese patients leads to persistent respiratory events 2
• Failing to account for mask leaks reduces treatment effectiveness 2
• Not providing adequate pressure to overcome intrinsic PEEP increases work of breathing 2
• Interpreting residual AHI data in isolation without considering clinical symptoms and mask leaks 3
• Definitions of residual AHI vary significantly among CPAP manufacturers; changing brands may show different values without actual change in apnea control 3

Monitoring Efficacy

Target Goals

• Achieve control of breathing events plus ≥15 minutes in supine REM sleep 1
• Maintain control for ≥30 minutes without breathing events before finalizing pressure 1
• Effective use is defined as ≥4 hours per night on 70% of nights, though benefits exist even at 2 hours 3

Follow-Up

• Early objective follow-up is essential, with monitoring starting in the first week, as early abandonment predicts long-term non-adherence 3
• Regular reassessment of pressure requirements is recommended, especially for patients with weight changes 2