Ultrasound-guided intrathecal pump access and prevention of the pocket fill.

OBJECTIVE Intrathecal pump drug refill may result in significant adverse outcome and complications. Thus far, 351 reports from around the world have been received by Medtronic Inc. related to occurrence of pocket fill, including eight lethal events. Ultrasound-assisted pump port access has been previously described, but did not result in wide acceptance in routine practice due to cumbersome and unreliable setup. This study outlines the methodology of real-time ultrasound-guided pump refill. DESIGN Preclinical feasibility study. SETTING   University of Washington Body Willed Program laboratory. INTERVENTIONS Using unembalmed cadaver model clinical scenarios of either inverted or deeply implanted pump were replicated. Sonographic images of those conditions were studied and an ultrasound-guided technique for accessing the pump injection port was developed. The ability to correctly identify pump versus pocket fill using ultrasonography was evaluated. OUTCOME MEASUREMENTS Positive and negative predictive value of correct needle placement, assessment of learning curve for inexperienced user, description of ultrasonography of inverted pump. RESULTS Both positive and negative predictive values reached 100%. Mastering the technique easy and uneventful. Inverted pump has a distinctive sonographic appearance. CONCLUSIONS Ultrasound-guided intrathecal pump access is a feasible and simple technique that may improve maintenance, routine device care, and prevent serious complications related to erroneous subcutaneous injections of concentrated medications. Clinical validation will be necessary in the future.