A CLINICAL-EVALUATION OF THE CODMAN MICROSENSOR FOR INTRACRANIAL-PRESSURE MONITORING

The strain-gauge Codman MicroSensor intracranial pressure (ICP) transd ucer has shown consistently good laboratory performance. To assess the practical performance of the system in patients following acute brain injury, 10 patients were fitted with a MicroSensor and a second ICP m onitor. In five cases this was a fibre-optic transducer and in five ca ses an intraventricular fluid-filled device. Paired ICP values were re corded every 5 min. ICP values ranged from 0 to 31 mmHg. Altman-Bland plots showed that individual readings could differ by as much as 9 mmH g. Further analysis showed that much of this disagreement could be exp lained try a constant offset on each occasion. Comparison traces of IC P in individual patients show high agreement in timing and size of cha nges. The unexplained constant offset leads to uncertainty about the t rue ICP. Treatment decisions are often based upon absolute levels of I CP and patient care may therefore differ depending upon the monitor us ed.