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.
With CPAP (SEE-pap), the air pressure is somewhat greater than that of the surrounding air, and is just enough to keep your upper airway passages open, preventing apnea and snoring. Although CPAP is the most common and reliable method of treating sleep apnea, some people find it cumbersome or uncomfortable.