What initial CPAP pressure should I set for an adult with moderate‑to‑severe obstructive sleep apnea (AHI ≥ 15) based on the diagnostic sleep study, and how should I adjust it if a titration study is not available?

Initial CPAP Pressure Settings for Moderate-to-Severe OSA

For an adult with moderate-to-severe OSA (AHI ≥15) without a formal titration study, start CPAP at 8 cmH₂O and use auto-adjusting CPAP (APAP) with a pressure range of 5–15 cmH₂O, provided the patient has no significant cardiopulmonary comorbidities. 1

Optimal Approach: Attended Titration Study

• The gold standard for determining optimal CPAP pressure is attended polysomnography-based titration, either as a split-night study or a dedicated full-night titration study 1
• Split-night titration is appropriate when OSA is confirmed after ≥2 hours of diagnostic sleep and the AHI is ≥15 events/hour 1
• During attended titration, pressure is increased in 1–2 cmH₂O increments at intervals no shorter than 5 minutes until apneas, hypopneas, respiratory effort-related arousals, and snoring are eliminated across all sleep stages and body positions 2
• The optimal pressure is the lowest level that controls respiratory events without inducing central apneas or causing patient intolerance 1

When Titration Study Is Not Available

Auto-Adjusting CPAP (APAP) as Initial Therapy

• APAP may be used as initial therapy for uncomplicated moderate-to-severe OSA in patients without significant cardiopulmonary comorbidities 1
• APAP devices automatically modify pressure breath-by-breath based on airflow limitation, snoring, or apneas 1
• APAP is contraindicated in patients with congestive heart failure, COPD, central sleep apnea, or hypoventilation syndromes 1
• Typical therapeutic pressures range from 5 to 20 cmH₂O, with most patients requiring 8 to 12 cmH₂O 1

Fixed-Pressure CPAP Starting Settings

• The recommended minimum starting CPAP is 4 cmH₂O in adult patients 2
• A higher starting CPAP (8–10 cmH₂O) may be selected for patients with elevated body mass index or for retitration studies 2
• The recommended maximum CPAP is 20 cmH₂O for patients ≥12 years 2
• If the patient awakens and complains pressure is too high, select a lower pressure that the patient reports is comfortable enough to allow return to sleep, then resume titration 2

Pressure Adjustment Algorithm

Indications to Increase Pressure

• Increase CPAP by at least 1 cmH₂O with an interval no shorter than 5 minutes if obstructive respiratory events persist 2
• Increase pressure if ≥2 obstructive apneas are observed for patients ≥12 years 2
• Increase pressure for persistent hypopneas, snoring, or respiratory effort-related arousals 2

When to Consider BiPAP

• If there are continued obstructive respiratory events at 15 cmH₂O, the patient may be transitioned to BiPAP 2
• BiPAP is also indicated when patients report high pressure intolerance, as it allows for lower expiratory pressure while maintaining adequate inspiratory pressure 3

Critical Follow-Up Protocol

• Early objective follow-up within 3–7 days of CPAP initiation (week 1) is essential to assess tolerance, address side effects, and review device download data 1
• Abandonment during the first week strongly predicts long-term non-adherence; prompt intervention is critical 1
• Residual AHI >5–10 events/hour on CPAP indicates inadequate pressure or persistent central events and warrants reassessment 1, 3
• Effective CPAP use is defined as ≥4 hours per night on ≥70% of nights, though a dose-response benefit is observed even at 2 hours/night 1

Special Populations Requiring Modified Approach

Contraindications to APAP (Require Attended Titration)

• Patients with congestive heart failure require careful titration; CPAP reduces cardiac afterload and improves left-ventricular function, but adaptive servo-ventilation is contraindicated in heart failure with reduced ejection fraction 1
• Patients with COPD (overlap syndrome) require careful titration due to hypercapnia risk and may benefit from bilevel PAP rather than CPAP 1
• Patients with suspected central sleep apnea or hypoventilation syndromes should undergo attended in-laboratory PSG rather than empiric APAP 1
• Patients with chronic opioid use, prior stroke, or neuromuscular disease require attended PSG for diagnosis and titration 1

Obesity Considerations

• Body mass index correlates with required CPAP pressure (ρ = 0.32, p <0.001), supporting a higher starting pressure in obese patients 2
• Weight loss of ≈10% of body weight significantly improves AHI and may lower required CPAP pressure 1

Common Pitfalls to Avoid

• Do not use APAP in patients with heart failure, COPD, or central sleep apnea; attended titration is required 1
• Do not ignore early adherence problems; intervene within the first week to improve long-term success 1
• Do not assume all apneas are obstructive; central sleep apnea requires different management and may be worsened by CPAP 1
• Recognize that residual AHI definitions vary among CPAP manufacturers; interpret device data in clinical context and do not rely on a single metric 1, 3
• Do not increase pressure exploration above the control level by more than 5 cmH₂O, as residual airway resistance can cause awakenings and insomnia 3

Patient Education Essentials

• Hands-on demonstration of mask application/removal, device power-on/off, humidifier filling, and basic troubleshooting is essential 1
• Patients should avoid alcohol, sedative-hypnotics, and opioids because these agents depress upper-airway tone and worsen OSA 1
• Gradual desensitization—wearing the mask while awake for progressively longer periods—helps patients with claustrophobia; nasal pillows are a useful initial option 1