PROSPECTIVE-STUDY OF ZERO DRIFT IN FIBEROPTIC PRESSURE MONITORS USED IN CLINICAL-PRACTICE

One hundred and one fiberoptic pressure transducers (59 subdural and 4 2 ventricular) were studied in 86 patients (some in whom more than one device had been inserted). Only four complications occurred: two tran sient cerebrospinal fluid leaks after removal and two clinically insig nificant intracerebral hematomas. No intracranial infections could be attributed to the devices. Technical problems occurred 23 times, with 11 devices ceasing to function before removal, seven becoming displace d, and five microventricular catheters failing to enter the ventricles . Zero-drift readings were obtained for 83 devices at the time of remo val (median 66 hours after insertion, range 2 hours-13 days). There wa s a clear negative bias in the readings (median -3), with a wide range of values (-12 to +14 mm Hg; interquartile range -6 to -1) that was a pparent even in the first 3 days of use. There was no important relati onship between zero drift and any recorded variable. It is concluded t hat zero drift of fiberoptic pressure transducers is a significant pro blem and that undue reliance should not be placed on intracranial pres sure readings from these devices in isolation from other clinical and radiological information.