, 1:S3,
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Date: 23 Dec 2004

In-vitro-testing of 1318 hydrocephalus valves. An overview of solved and unsolved problems

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Background

Between 1962 and 1979 only 121 valves have been tested. In 1980 Ekstedt published the first major series of 180 specimens. Now we register >1318 valves tested in vitro by 78 authors. Unfortunately cumulative or meta-analyses of the results are not available.

Materials and Methods

All papers including technical reports etc. related to valve-tests were evaluated; double publications of the same material were counted once, and papers of companies were excluded.

Results

96% were investigated in 4 countries: 9.0% in USA and England, 14.6% in Sweden and 63.9% in Germany. The number of specimen per group ranged from 1–643, the tested designs from 1–87. Unfortunately in most early, and also current papers the pretest procedures (de-aeration, pre-perfundation) were not described. In 10 papers, the temperatures in 7 of the test-fluids are missing, the same is true for many methodological details. Most authors measured the resistance-pressure with a given flow, a few the flow dependent of p ...