Positive airway pressure (PAP) is a standard treatment for patients with obstructive sleep apnea (OSA), a sleep related breathing disorder characterized by full or partial occlusion of the upper airway during sleep. Standard sleep medicine practice involves manual pressure adjustment by a sleep technologist during attended laboratory polysomnography (PSG) to eliminate obstructive respiratory-related events. A PAP delivery system consists of three main components: a PAP device; a nasal, oral, or oronasal interface (i.e., nasal mask, nasal pillows, full-face mask) held snug to the face by headgear; and a flexible hose that connects the device to the interface. A PAP device is basically an air pump (fan-driven or turbine system) that draws in external, filtered air and delivers pressurized airflow, which is adjustable by varying the pressure valve diameter or fan/turbine speed. PAP devices are divided into four basic types depending on their pressure delivery system: (1) Continuous positive airway pressure (CPAP), which delivers a single, fixed pressure to the patient during the night; (2) bi-level positive airway pressure (BPAP), which delivers a higher inspiratory PAP (IPAP) than expiratory PAP (EPAP); (3) auto-titrating positive airway pressure (APAP), which automatically increases CPAP or BPAP (IPAP/EPAP) as needed to maintain airway patency and then decreases the pressure if no abnormal respiratory events are detected within a set period of time; and (4) adaptive servoventilation (ASV), which uses a servocontroller that automatically adjusts pressure by breath-by-breath analysis to maintain a steady minute ventilation especially in heart failure patients with central sleep apnea and/or Cheyne-Strokes respiration.
Journal of Clinical Sleep Medicine, Vol. 4, No. 2, 2008