Understanding CPAP Titration
CPAP is not a plug-and-play therapy. The efficacy of the device depends entirely on finding the precise atmospheric pressure required to stent the airway open without causing intolerance.
What is Titration?
Titration is the process of determining the optimal positive airway pressure (measured in centimeters of water, cmH2O) needed to eliminate obstructive apnoeas, hypopneas, and flow limitations.
The In-Lab Titration Study
Traditionally, titration is performed overnight in a sleep lab. A technician remotely adjusts the pressure while you sleep, observing your EEG and respiratory effort.
- Starting Pressure: Usually low (e.g., 4 cmH2O) to allow the patient to fall asleep.
- Upward Titration: If respiratory events occur, the tech increases pressure by 1-2 cmH2O.
- Optimal Pressure: The lowest pressure that resolves all events in all sleep stages (especially REM, when muscle tone is lowest) and in all body positions (especially supine).
Fixed CPAP vs. APAP (Auto-titrating)
Fixed Pressure CPAP
Delivers a constant pressure (e.g., exactly 10 cmH2O) all night. Often considered superior for patients who are highly sensitive to pressure changes waking them up.
APAP
Operates within a range (e.g., 6-14 cmH2O). An algorithm analyzes the breath wave and automatically raises pressure in response to snoring or flow limitation, and drops it when the airway is stable. Most modern machines are APAPs.
The 95th Percentile Rule
If you use an APAP, your clinical report will show a "95th Percentile Pressure." This is not your average pressure. It means that for 95% of the night, your pressure was at or below this number.
Clinicians often use this number to transition a patient from APAP to a fixed CPAP. For example, if your APAP range is 5-15, but your 95% pressure is consistently 11, setting a fixed CPAP to 11 cmH2O may provide more stable therapy.