The Accuracy of Template-Guided Refill Technique of Intrathecal Pumps Controlled by Fluoroscopy: An Observational Study.

Abstract

Intrathecal drug therapy is being utilized increasingly for the treatment of chronic refractory pain. However, performing the regular pump refill procedures caries the potential risk of medication injection into the subcutaneous tissue. The aim of this study was to assess the accuracy of this template-guided refill technique by means of fluoroscopic evaluation. In 23 patients, the difference between the identification of the reservoir fill port center using the manufacturer's template and fluoroscopic guidance was assessed on four consecutive refill procedures by a two physicians. A distance surpassing that between the center and the margin of the port (3.5 mm) was considered a clinically relevant deviation. Analyses were performed with a one-sample t-test, with p < 0.05 indicating statistical significance. The mean difference distance between identification markings of the target with fluoroscopic guidance and with the template was 8.2 mm, with limited variance (2.7 mm). For all individual refill procedures, the port center identification accuracy differed significantly from zero (all p < 0.001) and from the clinically relevant cut-off point of 3.5 mm (all p < 0.001). Only seven attempts (6.4%) were within the margins of the fill port. Our results suggest poor accuracy of insertion point identification using the template. This highlights the potential risk of errors related to identification of the puncture site using the template-guided technique.