Refill Procedures of Intrathecal Drug Delivery Systems With a Recessed Fill Port on the Pump Surface: A Prospective Comparison Study of Ultrasound-Guided vs. Blind Refill Technique

Abstract

Structural differences of implantable drug delivery systems (IDDSs) might have an impact on the efficiency of needle access to the reservoir fill port (RFP). The aim of this study was to assess the efficiency of RFP needle access with an ultrasound (US)-guided vs. a blind refill technique in IDDSs with a Recessed RFP (Recessed-RFP-IDDS). The primary outcome was the number of attempts needed to enter the RFP with a needle comparing the US-guided technique vs. the blind refill technique. The time to enter the RFP with the needle was a secondary outcome. We compared the amount of attempts between both techniques with the non-parametric Wilcoxon rank sum test. Fourteen adult patients underwent a total of 75 refills of their Recessed-RFP-IDDS during a period of 24 months. The median number of attempts to enter the RFP did not differ significantly between the US-guided technique and the blind refill technique (2.0 (IQR: 1-5) vs. 1.5 (IQR: 1-5.0), p = 0.572). The median time to enter the RFP with the needle did not differ significantly between both techniques (35.0 sec (IQR: 26.0-58.0) vs. 41.0 sec (IQR: 25.5-46.8), p = 0.878). The results of this study suggest that there is no difference in the RFP needle access efficiency between the US-guided and the blind refill technique in superficially located Recessed-RFP-IDDSs, if performed by experienced practitioners. However, the study did not address efficiency of the RFP needle access in IDDSs with aberrancy in pump location or refills performed by inexperienced staff.