A PROSPECTIVE COMPARISON OF FIBEROPTIC AND FLUID-FILLED SINGLE LUMEN BOLT SUBDURAL PRESSURE TRANSDUCERS IN VENTILATED NEUROSURGICAL PATIENTS

A clinical comparison was made between fibre-optic and fluid-filled Bo lt subdural pressure transducers in ventilated head injured patients. Twelve subjects had both devices inserted in neighbouring sites. In tw o patients there were obvious technical problems with the fibre-optic system and the results were therefore excluded from further analysis. In the remaining 10 patients, 2167 pairs of simultaneous recordings we re made for up to 9 days and the degree of correspondence studied. A q uarter of paired readings differed by more than 5 mmHg. There was no e vidence of any overall bias, but in individual patients one device oft en read higher or lower than the other. The proportion of closely corr esponding readings tended to diminish after 4 days. Therapeutically re levant episodes, where treatment might have been initiated on the basi s of the readings from only one of the two systems, were equally likel y with both devices and occurred on average approximately every 30 h. The relative accuracy of the two devices remains uncertain, but there is evidence suggesting that both were prone to errors.