title: How Much Cerebrospinal Fluid Should We Remove Prior to Measuring a Closing Pressure?
abstract: The objective of this study was to identify a relationship between cerebrospinal fluid (CSF) volume removal and change in CSF pressure in children with suspected idiopathic intracranial hypertension (IIH).
  
  
  
  We performed a cross-sectional study of children 22 years and younger who underwent a lumbar puncture (LP) and had a documented opening pressure, closing pressure, and volume removed. Relationship between volume removal and pressure change was determined using a fractional polynomial regression procedure.
  
  
  
  In the 297 patients who met the inclusion criteria, CSF pressure decreased by 1 cm H2O for every 0.91 mL of CSF removed if the maximum change in pressure was less than 15 cm H2O ( R2= 0.38).
  
  
  
  A linear relationship exists between the volume of CSF removed and the amount of pressure relieved when the desired pressure change is less than 15 cm H2O.
authors.affiliation: 1 Division of Pediatric Emergency Medicine, Department of Medicine, Boston Children's Hospital, Boston, MA, USA.
authors.forename: Son H
authors.initials: SH
authors.lastname: McLaren
authors.affiliation: 1 Division of Pediatric Emergency Medicine, Department of Medicine, Boston Children's Hospital, Boston, MA, USA.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Monuteaux
authors.affiliation: 1 Division of Pediatric Emergency Medicine, Department of Medicine, Boston Children's Hospital, Boston, MA, USA.
authors.forename: Atima C
authors.initials: AC
authors.lastname: Delaney
authors.affiliation: 1 Division of Pediatric Emergency Medicine, Department of Medicine, Boston Children's Hospital, Boston, MA, USA.
authors.forename: Assaf
authors.initials: A
authors.lastname: Landschaft
authors.affiliation: 1 Division of Pediatric Emergency Medicine, Department of Medicine, Boston Children's Hospital, Boston, MA, USA.
authors.forename: Amir A
authors.initials: AA
authors.lastname: Kimia
mesh_terms: D000293:Adolescent; D015992:Body Mass Index; D015170:Cerebrospinal Fluid Pressure; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D011559:Pseudotumor Cerebri / Q000175:diagnosis* / Q000503:physiopathology*; D012189:Retrospective Studies; D012727:Sex Characteristics; D013129:Spinal Puncture / Q000379:methods*
keywords: idiopathic intracranial hypertension; lumbar puncture; pseudotumor cerebri