Recently developed optical technology has yield a fiber-optic transducer-tipped catheter which can produce high fidelity pressure recordings, with the result that a virtually artifact-free measurement of intracranial pressure (ICP) has become possible. Calibration of this monitoring system is simplified so that only the relative zero has to be validated, but the deviation of zero level called by zero drift are enough to produce a large discrepancy in the resulting magnitude of the recorded pressure.In 28 cases : 17 cases with eneurysmal subarachnoid hemorrhage ; 11 cases with intracerebral hematoma or cerebral contusion, ICP was measured with a fiber-optic transducer-tipped catheter placed in subdural space or intraparenchyma within two weeks. In each case, we recorded the zero drift, the maximum and minimum values of ICP and the duration of monitoring, and made a observation of the catheter tip.The zero drift was dependent upon the duration of monitoring. When the larger value of zero drift was recorded, more clot or fibrin was obserbed on the catheter tip or with in the catheter.The present study demonstrated a correlation between the zero drift and the duration of monitoring, and the zero drift obserbed when using a fiber-optic transducer-tipped catheter caused by presence of blood clots or fibrin on the catheter tip or with in the catheter.We suggested that ICP monitoring with a fiber-optic transducer-tipped catheter, with making a choice of measurement site, well-timed setting, and the transformation or heparincoating of the catheter tip, had bacome more sensitive and more precise without the disadvantage associated with zero drift.
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