A device and method for alleviating pressure on a portion of a patient's body that may be bed-ridden or otherwise constrained for long periods of time. A position of the mechanism is based upon a location or distribution of angiosomes in the body portion. The mechanism includes a pump, and a portable garment with inflatable channels and pressure relievers. The channels provide varying pressure on the body portion, a maximum pressure being set at a level sufficient for treating or preventing decubitus ulcer formation on the body portion. The channels are positioned based upon angiosome distribution in the portion of the body. The pressure relievers protect tissue on bony prominences from excess pressure.