As of our update last week, we have initiated two major components of our direct aspiration thrombectomy model. These include the addition of a differential pressure gauge across the simulated occlusion, as well as preliminary experiments relating intracranial pressure to overall arterial pressure in the two states of occlusion. In addition to these developments, we have acquired an electric pump, connectors, and tubing that will assist in our construction of a physiologically accurate model.

The major design aspect that we added to our model was a way to measure the pressure across our clot mechanism. To accomplish this task, we first severed the silicone tube mimicking the middle cerebral artery in two locations, allowing the insertion of two three-way connectors, or T-tubes. In order to access the connectors, a 15/32” drill bit was used to bore two adjacent holes in the Nalgene container. ½” grommets were then inserted into these locations, after which a differential pressure gauge had its leads connected to the vessel with silicone tubing. Images of the final product can be seen below.

After completing the alterations to our second prototype we decided to conduct preliminary experiments on the two factors we consider most promising towards increasing direct aspiration thrombectomy: the change in differential pressure across the clot as ICP increases and the change in pressure proximal to the clot as ICP increases. In order to have flow through our system, we placed our tube running through the clot into a water source ( A 0.5 L Dasani bottle), 25 mm above the clot and allowed pressure-driven flow through the cranial cavity and into a Styrofoam cup. As water flowed through the system we injected water into the plastic bladder within the Nalgene to increase ICP. During this process, we took measurements of either the differential pressure across the clot or the pressure proximal to the clot for every 5 mm Hg increase in ICP.

These results are shown below:

For these very preliminary tests, we found that there was no direct and significant correlation between proximal gage pressure or differential pressure with ICP.