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Template for disaster? Fatal injection into wrong port of implanted infusion pump


From the January 15, 2004 issue

PROBLEM: Implantable infusion pumps are sometimes used for long-term delivery of outpatient parenteral drug therapy. For intrathecal drug therapy, common uses include opiates to treat intractable chronic pain and baclofen to treat spasticity associated with multiple sclerosis, cerebral palsy, and spinal cord injuries. These pumps can accurately deliver very small volumes over long periods of time; therefore, concentrated medications may be used to extend the time between each refill of medication.

One distinct advantage of intrathecally delivered opiates is that much lower doses are needed than with other routes of administration. For example, the parenteral to intrathecal ratio for morphine is around 100:1. With lower doses, one would hope the risk of adverse effects would be lessened. However, massive intrathecal opiate overdoses have occasionally happened during the course of filling or refilling the pumps. The result has been a variety of adverse outcomes, including myoclonic seizures, pulmonary edema, respiratory depression, coma, and death.

For example, FDA has received reports of fatal overdoses caused by the accidental intrathecal injection of concentrated morphine while attempting to refill Medtronic SynchroMed infusion pumps. The SynchroMed pump is a titanium device about the size of a hockey puck. The pump is surgically implanted under the skin in the abdomen or flank area, with a catheter that resides in the intrathecal space. Centered on the front of the device is a small injection port leading to a drug reservoir. Reservoirs hold either a 10 mL or 18 mL volume and permit the drug supply to be replenished periodically via passage of a thin needle through the skin and into the reservoir port. One model of the pump also has a second port located on its periphery, which provides direct access to the intrathecal space via the catheter (see Figure ). This catheter access port is useful mainly for myelography, removal of cerebral spinal fluid (CSF), and troubleshooting problems (e.g., catheter patency). According to an FDA MedWatch report we reviewed, attempts to refill the pump reservoir using the catheter access port resulted in the accidental injection of concentrated morphine into the intrathecal space. The patient died as a result. Similar errors have been reported in the literature.1,2

Fatal errors caused by selecting the wrong port during pump refill can happen today. In the pump's refill kit, Medtronic supplies a template to locate the reservoir port. However, there's also a catheter access kit with a similar-looking template to find the side port for direct intrathecal access (see Figure 2). If the wrong kit is used, the medication intended for the reservoir could be injected into the intrathecal space.

Medtronic has taken a few steps to reduce the risk of an error. The catheter access port accepts only a very thin needle, which is included in the kit. The refill kit contains a larger needle that will not fit through the catheter access port. However, this safety feature will not prevent an error if a catheter access kit is accidentally used during a refill. If that happens, the template will locate the port with direct access to the CSF, and the thin needle provided with the kit will enter the port easily. Thus, medication intended for the drug reservoir could be injected into the catheter access port. The manufacturer also provides a cautionary pamphlet in the refill kit with a vague picture on the cover to warn users not to use the side catheter access port for refilling. Written cautions appear inside the pamphlet but are easily overlooked. A short written warning appears on the outside cover of the catheter access kit, but it, too, may not be seen. The templates themselves offer no warnings or differentiation to avoid such a devastating error.

SAFE PRACTICE RECOMMENDATION: Consider the following suggestions to reduce errors with implantable pumps.

FMEA. If you are using these devices or plan to use them, conduct a failure mode and effects analysis (FMEA) to determine additional ways that errors could happen and take action to reduce the risk of patient harm.

Standardize prescriptions. Create standardized order sets related to implanting, reprogramming, refilling, and other possible modalities (e.g., myelography) involving implantable pumps. Since the catheter access kit and refill kit have distinct product numbers that are clearly visible on the packages, consider including the kit number within the applicable order sets to ensure distribution and use of the kit that matches the desired function.

Educate users. If these pumps are used, it's critical to require special privileging and periodic competency validation for clinicians (e.g., physicians, physician assistants, nurse practitioners, nurses, pharmacists) involved in prescribing, implanting, programming, dispensing, or refilling the pumps or associated kits. All should be thoroughly oriented to the pump's use and function, procedures for implantation, programming, and refilling, and clearly understand the potential for life-threatening effects if an error occurs. If low usage makes it difficult to maintain proficiency, consider referring patients to another provider who handles implantable pumps more frequently.

Use pumps with a reservoir port only. When appropriate (e.g., pediatrics), implant pumps with a single port for the drug reservoir to reduce the risk of inadvertent direct administration of concentrated medications.

Separate the kits. Several panels on the cartons are blank. Thus, the manufacturer's labeling does not lend itself to easy identification and differentiation when the kits sit on a shelf. If pumps with both ports are used, store refill and catheter access kits in different locations. For example, keep refill kits in a secured area like the pharmacy (some may contain medications, baclofen for example), and catheter access kits (without medications) in another location like the physician's office or radiology. Also separate any refill kits that contain different doses of medication (e.g., baclofen).

Verify correct kit and port. Follow the written procedures provided in the manufacturer's kits for filling, programming, and refilling the pumps. Require the clinician who will be performing the procedure to verify the kit number with the number on the standard order form, and to open the kit himself so the warning messages are less likely to be overlooked. Require use of the template in the kit to locate the port, not just palpation. Take a "time out" and have two clinicians (or a clinician and a patient) independently double check the kit, template, and medication (if refilling the pump). During refill, attempt to validate puncture into the reservoir by aspirating the estimated volume of medication remaining before refilling the pump. During the procedure, inject and aspirate small amounts (3-5 mL) of the medication into the reservoir before refilling with the entire dose. The full volume injected should be readily aspirated and colorless. If suspicion exists that the aspirate is not medication, a sample can be tested with a reagent strip to determine the presence of glucose and protein, findings that would suggest, respectively, that cerebral spinal fluid or other body fluids have been aspirated in error. Fluoroscopy can also be used if location of the port is in doubt.

Provide patients with information. Since pump refills may occasionally occur in a location where the patient's medical records are not readily available, be sure to give the patient an updated information card/sheet with the device manufacturer and model number, reservoir capacity, date of last refill, medication, concentration, programmed dose, and any other important information. Clinicians should refer to this card during each encounter with the patient.

Be prepared for errors. Establish written guidelines for early recognition of an error (e.g., characteristic leg pain, seizures, and other symptoms specific to the drug) and prompt treatment in the event an error occurs. This may include an immediate process for active irrigation and drainage of the CSF, respiratory support, treatment for myoclonic seizure activity, and small incremental doses of reversal agents as appropriate.

Manufacturer changes. We have suggested changes to the labeling and packaging of the catheter access and refill kits, and better differentiation of the templates, to warn practitioners about the danger of direct intrathecal injection of medication intended for the reservoir. It would also be helpful if the manufacturer produced a short orientation video for clinicians.

Figure 1. SynchroMed pump (at www. medtronic.com). Note the catheter access port (top) and the reservoir port (center).

Figure 2. SynchroMed templates. These clear plastic overlays are placed over the palpated pump to help locate the correct port. Left: The refill kit template allows only reservoir access. Right: The catheter access kit template allows only catheter access. Accidental use of this template when refilling the pump has led to fatalities. (Newer design lists "SynchroMed" on all templates.)

References:

1. Sauter K, Kaufman HH, Bloomfield SM, et al. Treatment of high-dose intrathecal morphine overdose. J Neurology 1994; 81:143-46.

2. Wu CL, Patt RB. Accidental overdose of systemic morphine during intended refill of intrathecal infusion device. Anesth Analg 1992; 75:130-32

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