The victim was bound upon this wheel, on his knees, with his hands behind his back.
A continuous positive airway pressure (CPAP) machine was initially used mainly by patients for the treatment of sleep apnea at home, but now is in widespread use across intensive care units as a form of ventilation.
CPAP is the abbreviation for continuous positive airway pressure. This is a treatment for people who suffer from obstructive sleep apnea. With CPAP, a face mask is worn at night. The mask is attached to a machine that sends pressurized air into your airway, keeping it open while you sleep. This can help to eliminate snoring and other sleep apnea symptoms.