5.1 PAP Therapy & Titration Protocols

Why PAP Titration Dominates Domain 4

Treatment and Intervention (Domain 4) carries a 27.3% blueprint weight on the RPSGT exam administered by the Board of Registered Polysomnographic Technologists (BRPT) — tied with Sleep Study Preparation and Performance (also 27.3%) as the largest tested domain. The exam delivers 175 multiple-choice questions (150 scored, 25 unscored pretest items) in a 3-hour window, and you pass with a scaled score of 350 on a 200-500 scale. Roughly 1 in 4 scored questions touches PAP, so titration mastery is the highest-yield study you can do.

These questions reward candidates who know the American Academy of Sleep Medicine (AASM) manual titration algorithm rather than lab-specific habits. The exam frames titration as a protocol-driven skill: recognize the event, apply the rule, judge the result.

Positive airway pressure (PAP) works as a pneumatic splint. Pressurized air delivered through a mask holds the upper airway open during sleep, preventing the collapse that produces apneas, hypopneas, and snoring. Your job during a titration is to find the lowest pressure that eliminates obstructive respiratory events, snoring, and respiratory effort-related arousals in all sleep stages and body positions — especially supine REM sleep, where airway muscle tone is lowest and collapsibility is greatest. A pressure that controls events in lateral non-REM but fails in supine REM has not finished the job.

PAP Modes You Must Distinguish

Bold the distinction the exam loves: CPAP delivers one pressure; BiPAP delivers two. EPAP primarily resolves obstructive apneas and maintains airway patency; raising IPAP — widening the IPAP-EPAP difference, the pressure support — primarily resolves hypopneas, snoring, and supports ventilation. A worked example: a patient at CPAP 16 still hypopneic but apnea-free likely needs a bilevel switch where you hold EPAP and raise IPAP to widen pressure support, not simply more fixed pressure.

A safety contraindication to memorize cold: ASV is contraindicated in symptomatic chronic heart failure with a left ventricular ejection fraction of 45% or less, per the SERVE-HF trial, which found increased cardiovascular mortality. AVAPS and ASV are easy distractor swaps — AVAPS targets a tidal volume for hypoventilation; ASV smooths central/periodic breathing.

The AASM Manual CPAP Titration Algorithm

Start CPAP at a minimum of 4 cm H2O for adults (lower starting pressures may be used in children or very small adults). From there, the 2008 AASM clinical guideline directs you to increase pressure by at least 1 cm H2O, with an interval no shorter than 5 minutes between changes, whenever you observe any of the following while the patient is asleep on PAP:

• At least 2 obstructive apneas
• At least 3 hypopneas
• At least 5 respiratory effort-related arousals (RERAs)
• At least 3 minutes of loud or unambiguous snoring

Memorize this as "2-3-5-3". The exam will give you a scenario with a count and a clock and ask whether the rule is met — both the event threshold AND the 5-minute spacing must be satisfied.

Bilevel and Pressure Ceilings

• The recommended maximum CPAP is 15 cm H2O for children under 12 and 20 cm H2O for everyone else.
• Switch to bilevel if the patient is uncomfortable or intolerant of high CPAP, or if obstructive events persist at 15 cm H2O.
• On bilevel, raise IPAP and/or EPAP by at least 1 cm H2O using the same event-based triggers. The minimum IPAP-EPAP difference is 4 cm H2O and the recommended maximum difference is 10 cm H2O. Maximum IPAP is 20 cm H2O (children under 12) or 30 cm H2O (others).
• After events are controlled, perform down-titration / pressure exploration when sleep is stable to confirm the lowest effective pressure, then capture an extended period of supine REM at the selected pressure to validate the result.

Titration Grading: Optimal, Good, Adequate, Unacceptable

The 2008 AASM guideline defines four grades describing how well a titration achieved control. They rest on the residual respiratory disturbance index (RDI) measured for at least 15 minutes at the selected pressure and whether supine REM sleep was recorded.

A repeat titration should be considered when the result is Unacceptable and may be considered for an Adequate study — a frequent exam decision point. The classic trap: a beautiful RDI of 2 for 30 minutes but no supine REM is Adequate, not Optimal, because the lowest-tone, highest-risk state was never stress-tested.

Split-Night Conversion Criteria

A split-night study uses the first part of the night for diagnosis and converts to PAP titration in the same session:

• Convert when the diagnostic AHI is >= 40 during a minimum of 2 hours of recording.
• An AHI of 20 to 40 may justify conversion using clinical judgment (severe desaturation, comorbidity).
• Reserve at least 3 hours for titration so pressure exploration and supine REM can be captured. Too little remaining night is a common reason a split-night fails to reach Optimal.

Pediatric Titration Differences

Children are not small adults on a PAP study. Pediatric airways desaturate quickly and tolerate a narrower pressure window, so the protocol is more conservative:

• Lower starting and maximum pressures — recommended maximum CPAP 15 cm H2O and maximum IPAP 20 cm H2O for children under 12, versus 20 and 30 in adults.
• Smaller increments and tighter event thresholds — pressure may be raised in increments as small as 0.5-1 cm H2O, and as few as 1 obstructive apnea, 1 hypopnea, 3 RERAs, or 1 minute of loud snoring can justify an increase. Compare this to the adult "2-3-5-3" rule and note how every number tightens.
• Mask fit is decisive — leak tolerance is far lower because tidal volumes are small, so a leak that an adult tolerates can corrupt a child's titration. Desensitization before lights-out is often required.
• A pediatric AHI is interpreted against age-based norms: an obstructive AHI > 1 is generally abnormal in children, unlike the adult diagnostic threshold of 5.

Common Pediatric Trap

The exam may show a child with an AHI of 4 and ask if it is normal. Against adult criteria it looks borderline; against pediatric norms (AHI > 1 abnormal) it is clearly abnormal. Always anchor the interpretation to the patient's age group before choosing an answer.