Abstract
A new pressure transducer for epidural application which the authors developed to reduce the following four factors generally affecting epidural pressure (EDP) values registered on a transducer; 1) transducer characteristics, 2) effects of dural tension, 3) stress concentration effect due to minute irregularities on the dural surface, and 4) adhesion effect between the dura and transducer, is reported. Thus, if the theoretical coplanar measurement is obtained, the values registered by this pressure transducer closely approximates those of the cerebrospinal pressure directly beneath the dura. Even with these improvements, some discrepancies are observed between EDP and intraventricular pressure (IVP).
When EDP and IVP are compared, it is found that the difference in both values increases as IVP is higher in the same case, and EDP is usually higher than IVP. These discrepancies are mainly attributed to the fact that stress concentration effects could not be entirely eliminated. It was considered that a certain leeway percentage should be established as a safeguard in reading EDP values. No conclusion could be made as to the pressure gradient between EDP and IVP.
