Changes in intracranial pressure and epidural pulse waveform following cold injury.

Using anaesthetized spontaneously breathing cats, intracranial pressure (ICP) was monitored for twenty hours following the insult of cold injury; simultaneous recordings were also made of cerebral blood flow (CBF), epidural pulse waveform (EDP-WF), and systemic arterial pressure (SAP). Results could be divided into two groups depending on whether or not ICP exceeded 30 mmHg. In group one, in which marked increase in ICP including occasional episodes of pressure waves were observed, an initial increase in CBF and the changes in EDP-WF from polyphasic to monotonous at about 20 mmHg were characteristic. On the other hand, in group two, ICP never exceeded 30 mmHg, CBF slightly and continuously decreased and EDP-WF was polyphasic throughout the course. There were no significant differences in trends in SAP, in the extent of spread of oedema and in water content of the white matter between both groups. Therefore, the amount of cerebral blood volume (CBV) due to cerebral vasodilatation was considered to account for the further increase in ICP. Moreover, changes in EDP-WF were regarded as a useful indicator in predicting the trends in ICP since these changes could be observed in a relatively lower pressure range prior to a marked increase in ICP.