Some principles of postoperative epidural pressure monitoring.

A retrospective analysis is presented of 115 cerebral tumour cases where continuous epidural pressure (EDP) monitoring was carried out postoperatively using an implantable transducer constructed on a coplanar principle. Correct implantation of the transducer is crucial to reliable measurement. The influence of transducer location on EDP is highly significant and can be accounted for at least partly by hydrostatic forces. The effect of postural changes similarly has a hydrostatic component. Clinically complicated cases were usually easily distinguishable from uncomplicated cases with a similar transducer location. EDP is usually low in the absence of complications during the first 6 to 12 hours postoperatively. For postoperative monitoring, an EDP transducer should be placed as near to the site of surgery as possible for maximum sensitivity to local pressure changes and the earliest detection of complications.