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 most popular treatment for obstructive sleep apnea and stands for Continuous Positive Airway Pressure. It uses air pressure to keep the airway open during sleep. The CPAP machine varies in size. Most are about the size of a lunch box.