Real-time Noninvasive Monitoring of Intracranial Fluid Shifts During Dialysis Using Volumetric Integral Phase-Shift Spectroscopy (VIPS): A Proof-of-Concept Study

Neurocrit Care. 2018 Feb;28(1):117-126. doi: 10.1007/s12028-017-0409-4.


Background: Cerebral edema, which is associated with increased intracranial fluid, is often a complication of many acute neurological conditions. There is currently no accepted method for real-time monitoring of intracranial fluid volume at the bedside. We evaluated a novel noninvasive technique called "Volumetric Integral Phase-shift Spectroscopy (VIPS)" for detecting intracranial fluid shifts during hemodialysis.

Methods: Subjects receiving scheduled hemodialysis for end-stage renal disease and without a history of major neurological conditions were enrolled. VIPS monitoring was performed during hemodialysis. Serum osmolarity, electrolytes, and cognitive function with mini-mental state examination (MMSE) were assessed.

Results: Twenty-one monitoring sessions from 14 subjects (4 women), mean group age 50 (SD 12.6), were analyzed. The serum osmolarity decreased by a mean of 6.4 mOsm/L (SD 6.6) from pre- to post-dialysis and correlated with an increase in the VIPS edema index (E-Dex) of 9.7% (SD 12.9) (Pearson's correlation r = 0.46, p = 0.037). Of the individual determinants of serum osmolarity, changes in serum sodium level correlated best with the VIPS edema index (Pearson's correlation, r = 0.46, p = 0.034). MMSE scores did not change from pre- to post-dialysis.

Conclusions: We detected an increase in the VIPS edema index during hemodialysis that correlated with decreased serum osmolarity, mainly reflected by changes in serum sodium suggesting shifts in intracranial fluids.

Keywords: Cerebral edema; Dialysis dysequillibrium; ESRD; Intracranial fluid shifts; Noninvasive monitoring; VIPS.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Brain Edema / blood
  • Brain Edema / cerebrospinal fluid
  • Brain Edema / diagnosis*
  • Brain Edema / diagnostic imaging
  • Female
  • Humans
  • Kidney Failure, Chronic* / complications
  • Male
  • Middle Aged
  • Neurophysiological Monitoring / instrumentation
  • Neurophysiological Monitoring / methods*
  • Osmolar Concentration
  • Proof of Concept Study
  • Renal Dialysis*
  • Spectrum Analysis / instrumentation
  • Spectrum Analysis / methods*