The invention relates to a gas pressure measurement system comprising at least one gas circuit and at least one pressure sensor (6) arranged so as to be able to measure the pressure of the gas in at least part of the gas circuit, said at least one pressure sensor being protected by a protective membrane permeable to gas, arranged between said at least one pressure sensor and the gas circuit. It further comprises a flexible intermediate piece formed by an elastically deformable material arranged between said at least one pressure sensor and the protective membrane, said flexible intermediate piece comprising an internal passage putting the protective membrane and said at least one pressure sensor in fluid communication. Patient ventilation apparatus comprising a gas circuit able to convey gas between a gas source and a patient, as well as such a gas pressure measurement system.