Refill Port Identification of Intrathecal Drug Delivery System Devices With a Raised Fill Port

Abstract

The aim of this study was to assess the accuracy of the manual identification of the reservoir fill port (RFP) for refill of intrathecal drug delivery systems (IDDSs) with a raised RFP on the pump surface (raised-RFP-IDDSs), and compare this to previously reported data of patients with IDDSs with a recessed RFP (recessed-RFP-IDDSs). Nineteen patients underwent 2 IDDS refills for the treatment of noncancer pain or spasticity. The primary endpoint of this prospective observational study was the deviation between the needle insertion point and the RFP center, quantified by fluoroscopic visualization. A distance surpassing that between the center and the margin of the RFP of 4mm was considered a clinically relevant deviation. The results were compared with previously reported data of a patient cohort with recessed-RFP-IDDSs, and the differences were tested using Student's t-test. The mean deviation from the RFP center was 4.9mm (standard deviation=3.7). The RFP identification accuracy deviated more than the clinically relevant difference in 17 out of 35 instances (48.6%). The number of attempts and median procedural time was significantly correlated to the needle deviation. The mean deviations in the raised-RFP-IDDS cohort were consistently lower compared to the recessed-RFP-IDDS cohort (first refill procedure 4.0 vs. 8.5, P<0.001; second procedure 5.9 vs. 8.1, P=0.074). The results of this study suggest that the manual localization of the RFP for raised-RFP-IDDSs is moderately accurate, and more accurate if compared to previously published accuracy of the template-guided technique for recessed-RFP-IDDSs.