When lying down, the intraventricular pressure is controlled exclusively by the Differential pressure unit of the paediGAV. The freely movable balls of the gravitational unit do not provide any additional resistance in horizontal body position and automatically keep the flow channel open at this point. In the illustration a), the Differential pressure unit is closed and prevents any drainage of cerebrospinal fluid. If the intraventricular pressure increases, this force acts on the Differential pressure unit and finally causes the spring to give way and a gap to form between the cone and the ball, which now allows the cerebrospinal fluid to flow. The paediGAV is open in the illustration b).

In the upright position, the gravitational unit is automatically activated by the falling of the balls. A higher valve opening pressure is established, since the opening pressures of both valve mechanisms (differential pressure and gravitational unit) must now be overcome. If the patient stands up, the gravitational unit closes and the risk of overdrainage is reduced. Only when the sum of both valve units is exceeded by the increasing intraventricular pressure, the valve opens and thus enables the necessary drainage of the cerebral fluid.