Use of Color Flow Doppler Ultrasonography to Increase the Safety of Intrathecal Drug Delivery System Refills

Abstract

Intrathecal drug delivery systems are effective tools in the treatment of chronic pain or spasticity. Using intrathecal drug delivery systems, drugs are directly infused into the cerebrospinal fluid and gain access to critical receptors in the central nervous system. This delivery method allows for the use of markedly reduced doses of medications to produce the same effects as seen with higher orally administered doses. Reduced dosing produces fewer side effects, creating a more favorable treatment course for patients already suffering from chronic pain or spasticity. Complications with intrathecal drug delivery systems can occur during both the implantation process and the postoperative maintenance of the device. The most common procedure carried out during postoperative maintenance of these devices is the intrathecal pump refill. This procedure must be performed by experienced practitioners in a systematic way in order to prevent complications. The most dreaded of these complications is inadvertent injection of medication into the subcutaneous space as opposed to into the device, commonly referred to as a “pocket fill.” This paper describes and recommends the routine use of color flow doppler ultrasonography as an easy, safe, and effective tool to reduce the chance of a catastrophic “pocket fill.” Routine utilization of live color flow ultrasound guidance during pump refills allows the practitioner to carefully document flow of medication into the pump under the silicone septum. It also allows for demonstration of no leakage from, or fluid increase superficial to, the septum. Additionally, 2 ultrasound images are obtained to document color flow deep to the septum and no color flow/leak/fluid superficial to the septum. Although this complication is rare, it can lead to severe complications including oversedation, respiratory depression, and death. As such, we believe that the utilization of color phase doppler ultrasonography could further reduce this incidence. Key words: Analgesics, opioids, chronic pain, drug overdose, infusion pumps, implantable, injections, spinal, medication errors, spasticity, ultrasonics, methods, ultrasonography, interventional