Method of operation of a system (110) for supporting a patient, that comprises: - an inflatable mattress (10) comprising a first series of cells (21) and a second series of cells (25) - detecting means to detect the air pressure in the inside of the first series of cells (21) and the air pressure in the inside of the second series of cells (25) - a compressor (60) to inflate said inflatable mattress (10) - a valve (64) having a discharge connection (70) for the discharge in the outer ambient, said valve (64) being connected through a first conduit (72) to the first series of cells (21) of the inflatable mattress (10), through a second conduit (74) to the second series of cells (25), and through a feed conduit (62) to the compressor (60) - a controller (100), connected to the valve (64), to the pressure detecting means and to the compressor (60)characterized by the fact that the system comprises further: - at least one control chamber (30, 38, 48, 66, 94, 96, 120), placed under the patient and connected to a pressure sensor (98), to the compressor (60) in order to be inflated, and to a discharge (70) in order to be deflated said pressure sensor (98) being connected to the controller (100).The method is adapted to calculate the supporting pressure of a patient on an inflatable bedsores mattress (10) on the base of parameters such as, for instance, weight and position.
