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 stands for Continuous Positive Airway Pressure. It is one of the most popular treatment options for the sleep disorder and uses air to keep the airway open during sleep.