Clearance of Subarachnoid Hemorrhage from the Cerebrospinal Fluid in Computational and In Vitro Models

Subarachnoid hemorrhage (SAH) mostly occurs following the rupture of cerebral aneurysm causing blood to leak into the cranial subarachnoid space (SAS). Hemorrhage volume has been linked to the development of secondary vasospasm. Therefore, eliminating blood contaminants from the cerebrospinal fluid (CSF) space after the initial hemorrhage could improve patient outcomes and prevent the development of vasospasm. A number of clinical trials demonstrate that lumbar drainage effectively clears hemorrhagic debris from the cranial compartment. The benefits of optimal lumbar drainage rate and patient orientation are difficult to determine by trial-and-error in live patients, because of the invasive nature, limited subject availability and ethical considerations. Therefore, there is a lack of consensus about clinical guidelines for the use of continuous lumbar drainage following the ictus of SAH. A realistic bench-top model which reproduces the anatomy and CSF dynamics of the human central nervous system (CNS) was built to experimentally study contaminant clearance scenarios under lumbar drainage. To mimic a hemorrhagic event, porcine blood was injected at the basal cistern level of the bench-top model and the efficacy of lumbar drains was assessed experimentally for different drainage rates and patient orientations. In addition, the efficacy of blood clearance was predicted with a computational fluid dynamics (CFD) model. Bench-top experiments and CFD simulations identify body position and drainage rates as key parameters for effective blood clearance. The study findings suggest the importance of treatment in upright position to maximize contaminant diversion from the cranial CSF compartment. The bench-top CNS model together with the validated CFD predictions of lumbar drainage systems can serve to optimize subject-specific treatment options for SAH patients.