title: Repeatability of cerebrospinal fluid constant rate infusion study.
abstract: OBJECTIVE
  Infusion tests are important tools to assess cerebrospinal fluid (CSF)dynamics used in the preoperative selection of patients for shunt surgery, or to predict the scope of improvement from shunt revision. The aim of this study was to assess the repeatability of the key quantitative parameters describing CSF dynamics that are determined with infusion testing.
  
  
  METHODS
  Eighteen patients in whom a constant infusion test was repeated within 102 days, without any intermediate surgical intervention, were studied. From each test baseline ICP, baseline pulse amplitude, outflow resistance, elastance coefficient and slope of the amplitude-pressure line were calculated and investigated with a regression and Bland-Altman analysis.
  
  
  RESULTS
  Significant correlations (P < 0.01) were found for the outflow resistance (R = 0.96), the elastance coefficient (R = 0.778) and the slope of the amplitude-pressure line (R = 0.876). The estimated 95% confidence level for outflow resistance was 3 mmHg/ml min. Likewise, the elastance coefficient lay within a range of 0.16/ml and the slope of the amplitude-pressure line within 0.25. The most inconsistent parameter found were baseline ICP (R = 0.272) and baseline pulse amplitude (R = 0.171).
  
  
  CONCLUSIONS
  The results of this study imply that the parameters resulting from an infusion study have to be considered within a range rather than as an absolute value.
authors.affiliation: University of Aberdeen, Aberdeen, UK.
authors.forename: D M A
authors.initials: DM
authors.lastname: Swallow
authors.forename: N
authors.initials: N
authors.lastname: Fellner
authors.forename: G V
authors.initials: GV
authors.lastname: Varsos
authors.forename: M
authors.initials: M
authors.lastname: Czosnyka
authors.forename: P
authors.initials: P
authors.lastname: Smielewski
authors.forename: J D
authors.initials: JD
authors.lastname: Pickard
authors.forename: Z
authors.initials: Z
authors.lastname: Czosnyka
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002555:Cerebrospinal Fluid / Q000502:physiology; D015170:Cerebrospinal Fluid Pressure / Q000502:physiology*; D002557:Cerebrospinal Fluid Shunts / Q000379:methods*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D006801:Humans; D007223:Infant; D008875:Middle Aged; D015203:Reproducibility of Results; D012189:Retrospective Studies; D055815:Young Adult
keywords: cerebrospinal fluid; hydrocephalus; infusion test; intracranial pressure