Timing of intracranial hypertension following severe traumatic brain injury.

backgroundWe asked whether continuous intracranial pressure (ICP) monitoring data could provide objective measures of the degree and timing of intracranial hypertension (ICH) in the first week of neurotrauma critical care and whether such data could be linked to outcome.

methodsWe enrolled adult (>17 years old) patients admitted to our Level I trauma center within 6 h of severe TBI. ICP data were automatically captured and ICP 5-minute means were grouped into 12-hour time periods from admission (hour 0) to >7 days (hour 180). Means, maximum, percent time (% time), and pressure-times-time dose (PTD, mmHg h) of ICP >20 mmHg and >30 mmHg were calculated for each time period.

resultsFrom 2008 to 2010, we enrolled 191 patients. Only 2.1% had no episodes of ICH. The timing of maximum PTD20 was relatively equally distributed across the 15 time periods. Median ICP, PTD20, %time20, and %time30 were all significantly higher in the 84-180 h time period than the 0-84 h time period. Stratified by functional outcome, those with poor functional outcome had significantly more ICH in hours 84-180. Multivariate analysis revealed that, after 84 h of monitoring, every 5% increase in PTD20 was independently associated with 21% higher odds of having a poor functional outcome (adjusted odds ratio = 1.21, 95% CI 1.02-1.42, p = 0.03).

conclusionsAlthough early elevations in ICP occur, ICPs are the highest later in the hospital course than previously understood, and temporal patterns of ICP elevation are associated with functional outcome. Understanding this temporal nature of secondary insults has significant implications for management.