Function Of The Valve - MIETHKE miniNAV Mode D'emploi

miniNAV
Fig. 2: Pressure ratios for lying and upright positions
IVP : Intraventricular pressure
P Vli : Valve opening pressure in supine position (ball-cone valve only)
P Vst : Valve opening pressure in standing position (ball-cone valve + gravitational valve)
P B : Pressure in the abdominal cavity
P Hyd : Hydrostatic pressure
Lying down: IVP = P Vli + P B
Standing: IVP = P Hyd - P Vst - P B

FUNCTION OF THE VALVE

The operating principle of the miniNAV is illus-
trated in fig. 3. Fig. 3a shows the miniNAV
in the horizontal position. The ball-cone valve
is closed and drainage is prevented. If the
patient's IVP increases and continues to rise,
the spring pressure of the ball-cone unit will
be overcome. The sealing ball will move away
from the cone and a gap opens for fluid
drainage.
INSTRUCTIONS FOR USE | GB
Fig. 3: miniNAV
a) closed
b) open
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