Relation between epidural and ventricular pressures in canine brain: an experimental study.

Complications of epidural pressure (EDP) monitoring are much less severe than those of ventricular fluid pressure (VFP) monitoring. Hence, an insight into the relationship between the epidural and the ventricular pressures is of clinical importance. The pressure volume response as obtained during infusion tests performed on dogs can be categorized into two phases: (i) the latent phase and (ii) the monotonic rise phase. During the latent phase the VFP first rises to a maximum and then falls to a minimum, but these changes in VFP are not reflected in EDP. The latent phase is followed by the monotonic rise phase during which both VFP and EDP rise simultaneously and monotonically. Although the changes in VFP and EDP are similar the epidural pressure remains consistently less than the ventricular fluid pressure. Hence, changes in VFP can be estimated by monitoring EDP during the monotonic rise phase but not during the latent phase.