In vitro evaluation of hydraulic characteristics of prototype implantable intrathecal infusion pump

The use of the intrathecal infusion pump for therapeutic treatment and pain management is increasing. For example, one such application is the pain treatment of cancer patients suffering from severe chronic pain, where all other treatment methods have failed. This method is gaining popularity because of its high cure effect with low dosage. In this study, we developed a prototype implantable intrathecal infusion pump and evaluated its mechanical and hydraulic characteristics in vitro to determine how its performance varied under different environmental conditions. The data are reported as means (standard deviations). In the experiments, the prototype pump could control the micro-scale infusion amount, and its performance was affected by ambient temperature and pressure conditions. In a temperature change test, at a constant pressure of 1.0 atm, the minimal amounts of a bolus were 4.44 (1.07), 5.06 (1.17), and 5.54 (0.90) uL for the temperature of 27.5, 36.5, and 42°C, respectively. In a pressure change test, at a constant temperature of 36.5°C, the minimal amounts of a bolus were 5.06 (1.17), 5.94 (0.67), and 6.13 (0.39) uL for pressures of 1.0, 0.9 and 0.8 atm, respectively. These experimental results demonstrate the possibility of using the prototype pump as an implantable microvolumetric infusion device. However, this prototype pump will have to undergo further design enhancement before being clinically feasible for such an application.