The cerebral hemodynamics of normotensive hypovolemia during lower-body negative pressure

C. A. Giller, B. D. Levine, Y. Meyer, J. C. Buckey, L. D. Lane, D. J. Borchers

Research output: Contribution to journalArticlepeer-review

44 Scopus citations

Abstract

Although severe hypovolemia can lead to hypotension and neurological decline, many patients with neurosurgical disorders experience a significant hypovolemia while autonomic compensatory mechanisms maintain a normal blood pressure. To assess the effects of normotensive hypovolemia upon cerebral hemodynamics, transcranial Doppler ultrasound monitoring of 13 healthy volunteers was performed during graded lower-body negative pressure of up to -50 mm Hg, an accepted laboratory model for reproducing the physiological effects of hypovolemia. Middle cerebral artery flow velocity declined by 16% ± 4% (mean ± standard error of the mean) and the ratio between transcranial Doppler ultrasound pulsatility and systemic pulsatility rose 22% ± 8%, suggesting cerebral small-vessel vasoconstriction in response to the sympathetic activation unmasked by lower-body negative pressure. This vasoconstriction may interfere with the autoregulatory response to a sudden fall in blood pressure, and may explain the common observation of neurological deficit during hypovolemia even with a normal blood pressure.

Original languageEnglish (US)
Pages (from-to)961-966
Number of pages6
JournalJournal of neurosurgery
Volume76
Issue number6
DOIs
StatePublished - 1992

Keywords

  • hypovolemia
  • lower-body negative pressure
  • sympathetic nervous system
  • transcranial Doppler ultrasound

ASJC Scopus subject areas

  • Surgery
  • Clinical Neurology

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