Evaluation of craniospinal system condition using standardized volume-pressure loadings.

Abstract

Standardized volume-pressure craniospinal system loadings based on physiological loadings were developed in order to study the CSF outflow route efficiency and to evaluate the intracranial volume-pressure relations. The study was carried out on 10 cats. Standardized abdominal compression was applied in order to produce a central venous pressure increased and subsequently ICP increase to the level of 20 and 30 mmHg for 2 minutes. The abdominal compression test seems to be useful in the CSF outflow route evaluation. The orthostatic changes were studied in control animals and in cats with an epidural balloon. The animal body was evaluated to an angle of 50 degrees and 80 degrees with the head directed upwards and downwards. This test was found suitable for the intracranial volume reserve estimation. Similar application, especially in experimental conditions can be found in the hypercapnia test. PaCO2 concentration was increased by means of respiration with a gas mixture containing 5% CO2. A steady increase of ICP of 9 +/- 1 mmHg was obtained. Vascular dilatation resulted in an intracranial volume loading. The ICP response in subjects with normal CO2 response can be related to the intracranial volume reserve. The studies performed show the usefulness of the standardized volume-pressure loadings. The loadings applied are more physiological than lumbar infusion tests used so far.