The influence of hemorrhagic shock on brain perfusion in a swine model of raised intracranial pressure.

Overview

PURPOSE: In patients with hemorrhagic shock and an intracranial space occupying lesion (SOL), brain perfusion is severely compromised due to raised intracranial pressure (rICP), significantly worsening outcomes. This study aims to develop a swine model of a SOL with rICP and shock and characterize the effect on brain perfusion. METHODS: Ten male swine were divided into two groups- normal ICP (nICP) and rICP. rICP animals had an intracranial Fogarty balloon catheter inserted, which was infused with saline to simulate a SOL. Animals underwent hemorrhage to systolic blood pressures (SBP) of 60, 40, and 20mmHg. Cerebral blood flow (CBF) and cerebral blood volume (CBV) were measured using CT perfusion. RESULTS: The CBF/Mean arterial pressure (MAP) and CBV/MAP curves were modeled using non-linear regression, with both groups demonstrating a sigmoid relation. In both the CBF/MAP and CBV/MAP curves, animals with rICP had loss of autoregulation at a higher MAP compared to nICP. The curves were an excellent fit for CBF (nICP R² = 0.95; rICP R² = 0.77) and CBV (nICP R² = 0.96; rICP R² = 0.78). CONCLUSIONS: This study aids in quantifying the compounding insult of raised ICP and hemorrhage with regard to brain perfusion. Raised ICP results in autoregulatory failure at a higher MAP compared to animals with nICP. These results can help inform future studies that should be aimed at evaluating novel interventions for this complex clinical scenario.

European journal of trauma and emergency surgery : official publication of the European Trauma Society Journal