Over the years, a large number of procedures and diagnostic examinations have been developed in the research laboratory and then applied to clinical use. Senior readers will recall when it was necessary to contact someone in the research laboratory to obtain serum electrolyte levels. The determination of arterial blood gases is an example of a technique that was perfected in the research laboratory and has become indispensable when managing a variety of clinical problems.
The determination of intracranial pressure (ICP) is one of the latest techniques developed in the laboratory that is now available for clinical use. Measuring ICP is not new. It has been approximated by lumbar puncture or measured directly by ventricular puncture for years. Instruments that can be placed in the ventricle, over the surface of the brain, or in the epidural space have been developed. These are very ingenious, accurate, and reasonably safe. They all require