Abstract
In the nineties, more than 30 valves have been launched, most are "clones", but some
introduce new concepts (Diamond, Siphon-Guard, PaediGAV). Of the 22 designs we tested,
20 have no previous tests and 3 are low-cost valves from Mexico (Dewimed), Zimbabwe
(Harare-shunt) and England (Nottingham Shunt). 27 were tested using non-stop-perfusions
for 365 days, 8 for 168-294 and 3 for 2 days.
Results: Ranking of the mean relative deviation: adjustable valves 19%, gravitational
34%, simple ball 51 %, diaphragm 73%, distal slit 74 % and autoregulating valves 121
%. Ranking of physiological flow properties: gravitational >EquiflowTM >autoregulating >adjustable >ball >diaphragm >distal slit. Safety: The Equiflow were
highly susceptible to external pressure.
Conclusion: Most valves designed in the nineties showed inaccuracy, long-term-drifts,
safety deficits and hydraulic mismanagement similar to more than 400 previously tested
probes. With regard to accuracy and drift the ball designs were superior, but simple
and adjustable ball valves are at risk of overdrainage. The gravitational ball valves
(Cordis GCA, Miethke valves) showed the closest relation to physiological flow requirements.
Key words
Bench-test - Cerebrospinal fluid - Cerebrospinal fluid shunts - Gravitational valves
- Hydrocephalus - CSF overdrainage
