Intracranial pressure dynamics in patients with acute brain
damage.
Ursino, M., C. A. Lodi, S. Rossi, and N. Stocchetti.
Department of Electronics, Computer Science and Systems, University
of Bologna, Italy, First Service of Anaesthesiology and Intensive
Care, Civic Hospital, Parma, Italy, Neurosurgical Intensive Care,
General Hospital, Milano, Italy
APStracts 3:0528A, 1996.
The time pattern of intracranial pressure (ICP) during Pressure Volume
Index (PVI) tests was analyzed in 20 patients with severe acute brain
damage by means of a simple mathematical model. In most cases, a
satisfactory fitting between model response and patient's data was
achieved by adjusting only four parameters: i.e., the cerebrospinal
fluid (CSF) outflow resistance, the intracranial elastance
coefficient, and the gain and time constant of cerebral
autoregulation. The correlation between the parameter estimates was
also analyzed to elucidate the main mechanisms responsible for ICP
changes in each patient. Starting from information on the estimated
parameter values and their correlation, the patients were classified
into two main classes: those with weak autoregulation (8 cases out of
20) and those with strong autoregulation (12 out of 20). In the first
class, ICP mainly reflects CSF circulation and passive cerebral blood
volume changes. In the second, ICP exhibits paradoxical responses,
imputable to active changes in cerebral blood volume. Moreover, in 2
patients of the second class, the time constant of autoregulation is
found to be significantly increased (> 40 s). The correlation
between the parameter estimates turned out to be significantly
different in the two classes of patients, suggesting the existence of
different mechanisms responsible for ICP changes. Moreover, analysis
of the correlation between the parameter estimates might give
information on the directions of parameter changes which have the
greater impact on ICP.
Received 21 June 1996; accepted in final form 29 October 1996.
APS Manuscript Number A579-6.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996