The electronic controller is programmed to alternate the air cells every few minutes, so that the deflated cells will become inflated while the inflated air cells become deflated. For maximum therapy and patient comfort, air cells should run horizontally across the bed. This ensures that the patient's body receives both support and pressure relief from head to foot. Since it is the deflated air cells that provide therapy, it is important that the system have the capability to deflate or remove, the air cell away from the body as much as possible. Some systems claim to be alternating pressure but studies show there is little, if any, differentiation between the inflated and the deflated air cells.
Some systems deflate every third air cell instead of every other.
It is crucial to achieve a proper balance between the deflated and inflated air cells. Low Air Loss is the industry term for a therapeutic mattress system where low volumes of air escape out of the mattress. While the purpose of alternating pressure is to address constant pressure, low air loss assists in the management of heat and moisture, two other causes of pressure sores. In order for a low air loss system to benefit the patient, air must somehow reach the patient's skin. It is common for inexpensive systems to have air escape through pinholes in the air cells.