Moist heat is applied in the form of hydrocollator packs.  The packs are heated in water which is maintained at 140 degrees F. Before application, the packs are wrapped in toweling to protect the patient from burns.  Silica is the major ingredients in the packs . When the gel is dry, it is in powder form. When wet, it becomes gel-like. This material absorbs water, and heat is retained for 20 to 30 minutes as opposed  to the rapid dissipation of heat from toweling or blanket material. There are a variety of packs available, allowing for conformity to the areas being treated.



  1. Blood flow (arterial and venous).
  2. Relaxes muscles.
  3. Reduces pain by stimulating non-pain fibers.
  4. Superficial



  1. Relief for acute or chronic
  2. Various inflammatory injuries:
    1. Bursitis
    2. Tendonitis
    3. Myositis
    4. Arthritis
  3. Muscle spasm