Intracranial pressure and outcome in critically ill patients with aneurysmal subarachnoid hemorrhage : a systematic review

BACKGROUND: Evidences supporting the use of intracranial pressure (ICP) monitoring after aneurysmal subarachnoid hemorrhage (aSAH) are limited. The aim of our paper was to examine whether elevated intracranial pressure and ICP- derived variables predict mortality and functional outcomes after aSAH. EVIDENCE ACQUISITION: A systematic review of the literature was performed through PubMed and Cochrane databases up to June 2015. Population was restricted to aSAH patients requiring admission to the intensive care unit. ICP was included in the analysis as absolute value as well as variables derived from ICP monitoring (pressure reactivity index. ICP pulse wave amplitude. ICP-arterial blood pressure wave amplitude correlation and ICP variability). Outcomes included mortality, neurological recovery and delayed cerebral ischemia (DCI). Quality of evidence was rated using the GRADE system. EVIDENCE SYNTHESIS: Twenty-six studies were examined. Due to heterogeneity in qualifying studies, a meta-anal- ysis could not be generated. We found a correlation between elevated ICP and mortality. However. ICP absolute values were not independent predictors of long-term functional outcomes (low quality of evidence). A variable relationship between elevated ICP and DCI was found (very low quality of evidence). ICP-derived variables had higher accuracy than ICP absolute values in predicting functional outcomes (moderate quality of evidence). CONCLUSIONS: Elevated ICP was associated with higher mortality however absolute ICP values per se were not independent predictors of functional recovery. Variables derived from ICP monitoring are more accurate than ICP absolute values in predicting outcome. Given the absence of good quality data, additional large studies may help to better define the prognostic value of ICP after aSAH.