Continuous monitoring of intracranial compliance after severe head injury: relation to data quality, intracranial pressure and brain tissue PO2

The objective of the present study was to test the new continuous intracranial compliance (cICC) device in terms of data quality, relationship to intracranial pressure (ICP) and brain tissue oxygenation (PtiO2). A total of 10 adult patients with severe traumatic brain injury underwent computerized monitoring of arterial blood pressure, ICP, cerebral perfusion pressure, end- tidal CO2, cICC and PtiO2 providing a total of 1726 h of data. (1) The data quality assessed by calculating the 'time of good data quality' (TGDQ, %), i.e. the median duration of artefact-free time as a percentage of total monitoring time reached 98 and 99% for ICP and PtiO2, while cICC measurements were free of artefacts in only 81%. (2) Individual regression analysis showed broad scattered correlation between cICC and ICP ranging from low (r = 0.05) to high (r = 0.52) correlation coefficients. (3) From 225 episodes of increased ICP (ICP > 20 mmHg > 10 min), only 37 were correctly predicted by a preceding decline in cICC to pathological values ( < 0.5 ml/mmHg). (4) In all episodes of cerebral hypoxia (PtiO2 < 10 mmHg > 10min), cICC was not pathologically altered. Based on the present results, we conclude that the current hardware and software version of the cICC monitoring system is unsatisfactory concerning data quality, prediction of increased ICP and revelance of cerebral hypoxic episodes.