title: Cerebrospinal fluid outflow and intracranial pressure in hydrocephalic patients with external ventricular drainage.
abstract: OBJECTIVE
  The aim of this study was to monitor the 24 h cerebrospinal fluid (CSF) outflow and intracranial pressure (ICP) in hydrocephalic adult patients with external ventricular drainage (EVD).
  
  
  METHODS
  Twelve patients (5M/7F) aged 30-69 years suffering from acute hydrocephalus requiring EVD were admitted in the neuro-intensive care unit. The CSF collecting bag was continuously weighted using a high-precision scale, the filtered output of which was fed at 1 Hz to a computer and converted to flow (Q'ext(csf)). ICP was also recorded.
  
  
  RESULTS
  One patient was excluded because more than 80% of the Q'ext(csf) data were rejected by the system. The mean +/- SD Q'ext(csf) and ICP were respectively 7.5 +/- 3.4 ml/h (range 1.6-12.1 ml/h) and 12.4 +/- 2.7 mmHg. Two patterns of Q'ext(csf) were identified: a continuous profile and a discontinuous one with numerous bursts frequently associated with manoeuvres such as cough or chest physiotherapy. The short-term variations of Q'ext(csf) and ICP were usually unrelated.
  
  
  CONCLUSIONS
  The study stresses the important inter and intra-subject variability of Q'ext(csf) in patients with EVD. The mean Q'ext(csf) is lower than the reference production rate (21 ml/h), raising the question of persistent CSF absorption and/or depressed secretion. The independent changes of Q'ext(csf) and ICP on the short term is likely to be explained by the pressure-volume characteristics of the intracranial space.
authors.affiliation: Unit of Paediatric Neurosurgery and Department of Neurosurgery, Nancy University Hospital, 29 Avenue du Marchal de Lattre de Tassigny, Nancy Cedex, France. o.klein@chu-nancy.fr
authors.forename: O
authors.initials: O
authors.lastname: Klein
authors.forename: B
authors.initials: B
authors.lastname: Demoulin
authors.forename: R T
authors.initials: RT
authors.lastname: Jean Auque
authors.forename: G
authors.initials: G
authors.lastname: Audibert
authors.forename: C
authors.initials: C
authors.lastname: Sainte-Rose
authors.forename: J-C
authors.initials: JC
authors.lastname: Marchal
authors.forename: F
authors.initials: F
authors.lastname: Marchal
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D002555:Cerebrospinal Fluid / Q000502:physiology*; D015170:Cerebrospinal Fluid Pressure / Q000502:physiology; D005260:Female; D006801:Humans; D006849:Hydrocephalus / Q000503:physiopathology* / Q000601:surgery; D007427:Intracranial Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D014696:Ventriculostomy