Epidural devices are significantly less accurate. In general complications related to ICP monitoring are rare. The greatest concern, ventriculitis, has never been demonstrated in prospective studies of clinically significant intracranial infections following ICP measurement. Irrigating ICP devices significantly increases the risk of colonisation. Treatment is removal of the ICP bolt.
Parenchymal catheters have a higher incidence of haematoma than other methods.
Malfunction of the devices does occur, and readings over 50mmHg may be inaccurate with higher rates of obsturction and loss of signal. While maintenance of cerebral perfusion pressure is important, it only measures one parameter affecting the delivery of oxygen to the neurons. CPP provides a pressure gradient governing CBF, but flow is then affected by the resistance of the cerebral vessels. Neuronal demand for oxygen is governed by their metabolic rate. Neurons with high activity levels require greater amounts of oxygen than those which are quiescent.