RELIABILITY OF EPIDURAL PRESSURE MEASUREMENT IN CLINICAL-PRACTICE - BEHAVIOR OF 3 MODERN SENSORS DURING SIMULTANEOUS IPSILATERAL INTRAVENTRICULAR OR INTRAPARENCHYMAL PRESSURE MEASUREMENT

OBJECTIVE: In recent years, new devices for epidural pressure (EDP) me asurement have been developed, with claims of improved accuracy. Howev er, there have been no new data from simultaneous pressure measurement s to reverse the skepticism regarding this technique. METHODS: The rel iability of EDP recording was investigated in 26 patients with severe head injuries, during simultaneous measurement of ipsilateral intraven tricular pressure (IVP) or intraparenchymal pressure (IPP). RESULTS: P eriods of simultaneous measurement ranged from 3.3 to 168 hours. Techn ical failure occurred in five cases. Clinically significant erroneous pressure values (defined as differences of > 10 mm Hg between EDP and IVP or IPP, lasting for > 10 min) occurred in 7 of 21 measurements (33 %). In three of these seven cases (43%) the difference between the EDP and the IVP or IPP remained nearly stable throughout the period of ob servation, whereas in four cases (57%) significant drifting over time was observed, analysis of the transfer function calculated for the fir st to sixth harmonics between the EDP and the IVP or IPP showed no sig nificant differences between the pulse pressure waveforms, even when s ignificant drifting of more than 20 mm Hg occurred. CONCLUSION: The re liability of EDP measurement has not improved, compared with 10 years ago. Using this technique, one must be aware of the possibility of ove restimating intracranial pressure by more than 10 mm Hg and the possib ility of significant drifting of EDP over time, which argues against t he use of this method even for trend analysis.