The CSF Pulse Pressure in Relation to Intracranial Elastance and Failure of Autoregulation

Analogous to the volume-pressure response (VPR), the CSF pulse pressure (CSFPP) is determined by two factors (1): I. the transient increase in cerebral blood volume per cardiac cycle (ΔV); and 2. the shape of the craniospinal volume-pressure (V/P) curve. The CSFPP can therefore be used as a measure of craniospinal elastance, provided ΔV is constant. Observations in patients have shown a linear relationship between CSFPP and intracranial pressure (ICP) implying a constant ΔV in the individual patient (2). At elevated ICP, however, some authors (2,3,4) have found a break point in this relationship above which the CSFPP increased more rapidly. The meaning of this break point is not yet fully understood. In order to study the concept of CSFPP as a parameter of craniospinal elastance, CSFPP was compared with VPR during cerebral compression in dogs. Special attention was paid to the occurrence of a break point and its physiological significance.