A new technique for monitoring epidural intracranial pressure

Measurement of intracranial pressure (ICP) has important uses in the diagnosis and treatment of various neurological disorders. For the past three years, the authors have been monitoring ICP in the operating room, intensive care units, and wards, with a pressure-sensitive on-off type of switch sensor. This sensor was originally developed by M. Numoto et al. , as a mechanical switch with electrical contacts. Employing the same on-off, pressure-sensitive switch, the contacts were changed to light-coupled fiberoptic threads. The monitor is commercially available with digital read-out and provision for continuous direct recording of pressure. The majority of cases in which ICP has been monitored were head trauma patients (37 cases). Monitoring has been particularly useful in aiding the management of patients with edema and in the detection of changes in ICP such as plateau waves. This monitor is relatively simple to operate; there are no indwelling catheters that must be flushed, nor is calibration needed after the sensor is inserted. The device is inherently safe, as the patient is connected to only a source of light and air.