What is a hydrocollator?

• A. Portable electric heating pad
• B. Dry heat lamp
• C. Canvas pack filled with gel and immersed in water
• D. Chemical coolant spray

Answer: (C)

A hydrocollator delivers moist heat by using heated gel-filled packs that are warmed in a hot water bath. The unit holds a tank of hot water, and flexible canvas packs filled with a gel (often silica-based) are immersed in that water to soak up heat. When applied to the body, the packs are wrapped in a towel to prevent burns and allow the moist heat to penetrate the tissues.

This description matches the option of a canvas pack filled with gel and immersed in water. It’s different from a portable electric heating pad (which provides dry heat), a dry heat lamp (infrared heat), or a chemical coolant spray (no heat involved).