title: The Intracranial Volume Pressure Response in Increased Intracranial Pressure Patients: Clinical Significance of the Volume Pressure Indicator.
abstract: BACKGROUND
  For patients suffering from primary brain injury, monitoring intracranial pressure alone is not enough to reflect the dynamic intracranial condition. In our previous study, a segment of the pressure-volume curve can be expressed by the parabolic regression model with single indicator "a". The aim of this study is to evaluate if the indicator "a" can reflect intracranial conditions.
  
  
  METHODS
  Patients with traumatic brain injury, spontaneous intracranial hemorrhage, and/or hydrocephalus who had external ventricular drainage from January 2009 to February 2010 were included. The successive volume pressure response values were obtained by successive drainage of cerebral spinal fluid from intracranial pressure 20-25 mm Hg to 10 mm Hg. The relationship between withdrawn cerebral spinal fluid volume and intracranial pressure was analyzed by the parabolic regression model with single parameter "a".
  
  
  RESULTS
  The overall mean for indicator "a" was 0.422 ± 0.046. The mean of "a" in hydrocephalus was 0.173 ± 0.024 and in severe intracranial mass with slender ventricle, it was 0.663 ± 0.062. The two extreme intracranial conditions had a statistical significant difference (p<0.001).
  
  
  CONCLUSIONS
  The indicator "a" of a pressure-volume curve can reflect the dynamic intracranial condition and is comparable in different situations. A significantly larger indicator "a" with increased intracranial pressure is always observed in severe intracranial mass lesions with cerebral edema. A significantly smaller indicator "a" with increased intracranial pressure is observed in hydrocephalus. Brain computed tomography should be performed early if a rapid elevation of indicator "a" is detected, as it can reveal some ongoing intracranial pathology prior to clinical deterioration. Increased intracranial pressure was frequently observed in patients with intracranial pathology. The progression can be differentiated using the pattern of the volume pressure indicator.
authors.affiliation: Department of Neurosurgery, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taoyuan, Taiwan.
authors.forename: Hung-Yi
authors.initials: HY
authors.lastname: Lai
authors.affiliation: Department of Neurosurgery, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taoyuan, Taiwan.
authors.forename: Ching-Hsin
authors.initials: CH
authors.lastname: Lee
authors.affiliation: Department of Neurosurgery, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taoyuan, Taiwan.
authors.forename: Ching-Yi
authors.initials: CY
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D001921:Brain / Q000000981:diagnostic imaging; D001930:Brain Injuries / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology; D004322:Drainage; D005260:Female; D006801:Humans; D006849:Hydrocephalus / Q000473:pathology / Q000503:physiopathology*; D007362:Intensive Care Units; D020300:Intracranial Hemorrhages; D019586:Intracranial Hypertension / Q000175:diagnosis; D007427:Intracranial Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed