Association among intracranial compliance, intracranial pulse pressure amplitude and intracranial pressure in patients with intracranial bleeds

Objective: To investigate the association among intracranial compliance (ICC), intracranial pulse pressure amplitude and intracranial pressure (ICP) in patients with intracranial bleeds. Methods: Five patients with intracranial bleeds had their ICC and ICP monitored during days 1-8 after ictus. The recordings were stored as raw data files and analysed retrospectively. The parameters mean ICC, mean ICP wave amplitude and mean ICP were determined and average values were calculated in 1 hour time periods. Results: A total of 262 1 hour recordings were analysed. There was a significant correlation between mean ICC and mean ICP wave amplitude and between mean ICC and mean ICP. The mean ICP wave amplitude was significantly higher during the 1 hour periods with mean ICC < 0.5 ml/mmHg and significantly lower during 1 hour periods with mean ICC 1.5-3.0 ml/mmHg. Correspondingly, in the 159 1 hour recordings with mean ICP wave amplitude >= 5.0 mmHg, mean ICC was significantly lower than in the 103 recordings with mean ICP wave amplitude < 5.0 mmHg. Mean ICP was normal (i.e < 20 mmHg) in 260 of 262 (99.2%) of the 1 hour recordings; in the 49 1 hour recordings with mean ICP > 15 mmHg, mean ICC was significantly lower than in the 213 recordings with mean ICP < 15.0 mmHg. Conclusion: In this cohort of pressure recordings, there was a strong association between ICC and intracranial pulse pressure amplitude. There also was a strong association between ICC and mean ICP, but mean ICP was normal in 260 of 262 1 hour recordings (99.2%).