Fixation control for a patient interface

Patient interface system, with

• a patient interface for providing a patient with a flow of gas, with a headgear for attaching the patient interface to the patient, and at least one adjustment mechanism for regulation of a force for attaching the patient interface to the patient with the headgear,
• a detector for monitoring a degree of blood flow through at least one blood vessel of the patient, with at least one sensor, at least one monitoring unit, and an evaluation unit, and
• a sound generator,
• wherein the at least one sensor is able to detect characteristic data of a blood flow through the at least one blood vessel and is connected to the at least one monitoring unit for transmitting the detected data to the at least one monitoring unit,
• wherein the at least one monitoring unit is able to receive the data from the at least one sensor and is able to assess the degree of blood flow through the at least one blood vessel based on these data,
• wherein the at least one monitoring unit is able to provide a signal based on the assessed blood flow through the at least one blood vessel,
• wherein the evaluation unit is designed to receive and to process the signal from the monitoring unit, and
• wherein the evaluation unit is configured to control the sound generator to produce an alarm if the signal indicates that a degree of blood flow within the at least one blood vessel or a degree of occlusion of the at least one blood vessel passes a predetermined threshold, said alarm indicating the patient that the attachment force of the patient interface is too strong and that the force has to be adapted by means of the at least one adjustment mechanism.