Cerebrospinal fluid-compensated medication reservoir for an implantable infusion device: Concept and preliminary evaluation

Abstract

Conventional gas-compensated medication reservoirs used for implantable infusion devices require perfect sealing of the gas chamber, because the gases used are generally toxic. In addition, the physical properties of selected gas critically affect the performance of infusion devices and hydraulic performance of the infusion device can be affected by the amount of medication discharged. In this study, we suggest a new medication reservoir that adopts a cerebrospinal fluid (CSF)-compensating mechanism, such that when a medication is released from the reservoir by a mechanical actuator, native CSF enters into the reservoir to minimize the build-up of pressure drop. We evaluated in vitro performance and conducted in vivo feasibility tests by using an intrathecal infusion device developed at the Korean National Cancer Center. Experimental results showed that the proposed CSF-compensated infusion pump was essentially less affected by ambient temperature or pressure conditions compared to the gas-compensated infusion pump. Moreover, it showed moderate implant feasibility and operating stability during an animal experiment performed for 12 days. We believe that the proposed volume-compensating mechanism could be applied in various medical fields that use implantable devices.