Valve and method to relieve gaseous pressure and arrangement for ventilating lungs

A method for relieving gaseous pressure in a branching unit providing a breathing gas for a subject inhalation and receiving an exhaled breathing gas, the branching unit comprising a Y-piece having at least three limbs, a first of the limbs being an inspiration limb for an inspired gas, the first limb having a first one-way valve to allow the inspired gas through the inspiration limb, a second of the limbs being an expiration limb for an expired gas, the second limb having a second one-way valve to allow the expired gas through the expiration limb, a third limb being a patient limb for carrying both the inspired gas and the expired gas to and from the lungs of a patient, the branching unit being in flow communication with a valve comprising an inlet port and an outlet port, the valve configured to close a gas discharge with a predetermined closing force when a breathing gas pressure of the branching unit is below a pressure determined by the predetermined closing force and to facilitate the gas discharge when a force due to the breathing gas pressure of the branching unit exceeds the pressure determined by the predetermined closing force, the valve being coupled to one of the Y-piece and the first limb and between the first one-way valve and the patient limb, the method comprising:

• determining an allowed branching unit breathing gas pressure limit information;
• acquiring a signal indicative of a prevailing breathing gas pressure in the branching unit;
• changing the predetermined closing force if the allowed branching unit breathing gas pressure limit information deviates from the predetermined closing force;
• comparing the signal indicative of a prevailing breathing gas pressure with the allowed branching unit breathing gas pressure limit information;
• if the signal indicative of a prevailing breathing gas pressure deviates from the allowed branching unit breathing gas pressure limit information, changing the closing force to meet the allowed branching unit breathing gas pressure limit information;
• operating an actuator coupled to the valve for the step of changing the closing force;
• controlling the actuator independently from a control unit operating an expiration valve of the branching unit;
• and
• urging the valve in a closed position when the actuator is inactive and the breathing gas pressure is below the closing force, and allowing the valve to open when the gas pressure exceeds the closing force as the gas flows from the inlet port to the outlet port.