Clinical evaluation of the InnerSpace fibreoptic intracranial pressure monitoring device

Objective: The aim of this study is the clinical evaluation of the intraparenchymal ICP monitor InnerSpace OPX 100. Methods: Sixty-four Inner Space OPX 100 transducers in 51 patients with severe head injury (42), intracranial spontaneous bleeding (6) or hypoxia (3) were studied. The transducer was placed in the frontal white matter. Thirty-nine patients received one catheter, eleven patients two catheters and one patient three catheters. The study period ranged from 10 hours-25 days; total study time was 421.5 days (mean duration 6.6 days). Results: In nine cases (14.1%) an inadequate location of the ICP transducer was found, but the accuracy of the measurement was not influenced. Dislocation of the transducer occurred in eight cases (12.5%) due to inadequate handling. A failed transducer was observed in four cases (6.3%) because of a damaged optical fibre (1) or inadequate handling (3). In one patient (1.9%) a minor local infection developed. In eleven cases (17%) a haematoma around the ICP sensor was observed. Six haematomas were small; five haematomas were larger than 1 cm in diameter. In two patients a large frontal haematoma developed after exchange of the transducer. Operative evacuation was necessary in both cases. Zero shift was below 2 mmHg in all catheters. Conclusion: It is concluded that the InnerSpace intraparenchymal ICP monitor is a reliable device: the rate of catheter related intracerebral haematomas, however, is not acceptable. This could be improved by a better fixation of the catheter in the burr hole in order to avoid micromovements of the transducer.