title: An adjustable CSF shunt: advices for clinical use.
abstract: OBJECTIVE
  The opening pressure and the resistance of a CSF shunt are essential for clinical use in order to set the proper opening pressure and to determine the shunt function in vivo. We find it of vital importance to validate and supplement the product description given by the manufacturer. The in vitro properties of a newly introduced, adjustable differential pressure valve with a siphon-preventing device (Strata valve) was compared with its predecessor (Delta valve).
  
  
  METHODS
  An automated, computerized experimental set-up based on regulation of pressure, built into an incubator at 37 degrees C, was used. Opening pressure, resistance and siphon preventing properties were determined. Six brand-new shunts of each type with catheters were tested. The Delta valves were at a performance level of 1.5.
  
  
  RESULTS
  The hydrodynamic properties of the Strata and Delta valves were similar. The anti-siphoning device was functioning for all valves. The estimated mean resistance for Delta and Strata shunts was 2.6 +/- 0.4 and 2.2 +/- 1.0 mmHg/ml/min, respectively. The mean opening pressure for the five performance levels of the Strata shunt are: 3.3, 5.1, 7.7, 10.7 and 13.1 mmHg. There may however, be considerable variations between the shunts.
  
  
  CONCLUSIONS
  The Strata shunt is a properly working adjustable valve with anti-siphoning device that showed good reproducibility concerning opening pressure and resistance. At performance level 1.5, the new Strata shunt was similar to its predecessor concerning opening pressure and resistance. The given values of the different opening pressures and resistance could be used for in vivo testing of the valve function with a standard lumbar CSF infusion test.
authors.affiliation: Department of Clinical Neuroscience, Umeå University, Umeå, Sweden. bo.lundkvist@neuro.umu.se
authors.forename: B
authors.initials: B
authors.lastname: Lundkvist
authors.forename: A
authors.initials: A
authors.lastname: Eklund
authors.forename: L-O D
authors.initials: LO
authors.lastname: Koskinen
authors.forename: J
authors.initials: J
authors.lastname: Malm
mesh_terms: D015170:Cerebrospinal Fluid Pressure / Q000502:physiology*; D002557:Cerebrospinal Fluid Shunts / Q000295:instrumentation*; D004867:Equipment Design; D006801:Humans; D006849:Hydrocephalus / Q000503:physiopathology* / Q000601:surgery*; D066298:In Vitro Techniques; D008422:Materials Testing; D008959:Models, Neurological; D010818:Practice Patterns, Physicians'; D015203:Reproducibility of Results; D012212:Rheology