Dual catheter and double-lumen cerebrospinal fluid shunt systems with backflow mechanisms.

Purpose: We previously developed a novel functional benchtop apparatus to simulate catheter occlusion in vitro utilizing avian vitelline membrane and chalaza to test catheter designs and de-obstruction techniques. Here, we study the integration of double-lumen catheter-mediated backflow in the shunt system assembly and its potential for an in-line de-obstruction of an obstructed ventricular catheter.

Methods: A double-lumen catheter was connected to a standard proximal shunt catheter for all trials. One limb of the double-lumen catheter was connected to the backflow mechanisms and allowed to loop back for fluid access. A micropump and a bi-corporal electromagnetic pump were utilized to provide various degrees of backflow at predetermined intervals. Flow rates were measured after initial occlusion and after implementation of the backflow mechanisms, and degrees of catheter blockage was calculated as a percentage of the unoccluded flow rate. Flow visualization was also used.

Results: In baseline blockage of less than 50%, the average occluding agent weighed 0.3-0.6 g with baseline flow rates of 8.5-11.9 mL/min. After 5 min of backflow using a micropump, the degree of blockage was reduced in 50% of trials. Additional backflow for 5 min did not provide further improvements in flow rate. In baseline blockage of greater than 50%, the average occluding agent weighed 0.8-1.3 g with baseline flow rates of 1.1-4.2 mL/min. After 5 min of backflow, the system demonstrated a decreased blockage in 20% of trials; additional backflow for 5 min further improved the flow rate in 40% of the total trials. Only magnetic plates provided enough force to provide pulsatile backflow in the bi-corporal electromagnetic system.

Conclusions: The preliminary results of connecting a standard proximal catheter in series with a double-lumen catheter show a slight change in the percent occlusion from the baseline status several times when the retrograde flow occurred via one limb of the catheter. Additionally, the de-obstruction seems related to the length of the interval of the backflow and the initial percentage occlusion of the proximal catheter. The statistical analysis does not reveal a statistically significant reduction in occlusion in the proximal catheter with either backflow interval.