PAP therapy (CPAP)
During sleep, air at a slight pressure is given through a mask worn on the nose or face. This air keeps the throat open like an air cushion.
A little more detail
Positive airway pressure (fixed-pressure CPAP, auto-adjusting APAP, bilevel BPAP) prevents the upper airway from closing during sleep pneumatically. The AASM 2019 guideline gives a strong recommendation for PAP therapy in adults with obstructive sleep apnea and excessive sleepiness.
Source: Patil SP, Ayappa IA, Caples SM et al. Treatment of adult obstructive sleep apnea with positive airway pressure: an American Academy of Sleep Medicine clinical practice guideline. J Clin Sleep Med. 2019;15(2):335-343. doi:10.5664/jcsm.7640