Objective Approach for Titration of Continuous Positive Airway Pressure in Patients with Obstructive Sleep Apnea Using Daytime Continuous Positive Airway Pressure Titration Based on Respiratory Movement Regularity

<b>Background/Objectives</b>: Continuous positive airway pressure (CPAP) is used to treat patients with obstructive sleep apnea (OSA) and has proven clinical efficacy for this condition. However, the objective method to determine the appropriate CPAP level for treatment is still unclear. Patients with OSA typically exhibit irregular respiratory efforts due to obstruction or narrowing of the upper airway during sleep. Treatment with an adequate CPAP level alleviates airway obstruction or narrowing, leading to more regular respiratory patterns. We aimed to develop an objective CPAP titration method using the respiratory regularity index (RRI) derived from respiratory movements. <b>Methods</b>: We conducted daytime CPAP titration in 10 patients with OSA. Respiratory movements were recorded by inductance plethysmography in three conditions: wake, apnea, and during CPAP therapy. The RRI of respiratory movements was calculated in each condition, and the CPAP level with the lowest RRI was identified as the appropriate air pressure level in each patient. CPAP therapy at the appropriate level determined by the study method was conducted for 2 months, after which efficacy was assessed by night polysomnography in the hospital. <b>Results</b>: The fixed air pressure level for the CPAP device was determined as 7.8 ± 0.7 cmH₂O based on our daytime CPAP titration method using the RRI. The apnea-hypopnea index improved significantly from before CPAP therapy (43.1 ± 15.3 h^-1) to during CPAP therapy (3.0 ± 2.1 h^-1) (<i>p</i> < 0.006). The Epworth Sleepiness Scale score decreased significantly during CPAP therapy. The lowest percutaneous arterial oxygen saturation values in each sleep stage also improved significantly with the CPAP determined by our daytime CPAP titration method. <b>Conclusions</b>: The study findings showed that our daytime CPAP titration method based on the RRI is an effective method for determining individualized appropriate CPAP levels in patients with OSA. The RRI-based daytime CPAP titration method offers a simplified approach to determining the adequate CPAP level for patients with OSA.