Implantation of Intrathecal Drug Delivery Systems

Published on 10/03/2015 by admin

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Chapter 16 Implantation of Intrathecal Drug Delivery Systems

Pyung-Bok Lee, MD, PhD, Sang-Chul Lee, MD, PhD, Yong-Chul Kim, MD, PhD

Opioids produce a profound inhibition of the evoked discharge of spinal nociceptive neurons, thereby inhibiting the transmission of pain. Intrathecally administered opioids have no effect on the motor function and autonomic responses. The analgesic effect of opioids is dose dependent and antagonized by naloxone.

Indications

Implantation of an intrathecal drug delivery system is indicated for:

Chronic, intractable pain of malignant and/or benign origin that responds to opioids (Box 16.1)

Long-term infusion of baclofen for severe spasticity of spinal or cerebral origin that responds to baclofen

Long-term intravascular infusion of antibiotics or drugs for chemotherapy

BOX 16.1 Patient Selection Criteria for Use of an Intrathecal Drug Delivery System

Patient with Cancer Pain

Opioid response demonstrated during the screening trial

No difficulty with catheter advance in the subarachnoid space

Inability to control pain with systemic opioids

Life expectancy > 3 months

Patient with Chronic Nonmalignant Pain

Opioid response demonstrated during the screening trial

More conservative treatments have failed

Further surgical intervention is not indicated

Patient has no untreated drug addiction

Psychological evaluation finds no evidence of compensatory need

Contraindications

Contraindications to implantation of an intrathecal drug delivery system are as follows:

Systemic infection

Pump cannot be implanted less than 2.5 cm from the surface of the skin

Known allergies to the materials or medications

Instrumentation

Equipment required for implantation of an intrathecal drug delivery system consists of the following:

Implantable intrathecal infusion pump (Figs. 16-1 and 16-2)

10-mL syringe for flushing the catheter access port and for skin infiltration

20-mL syringe for emptying the reservoir and filling the pump

22-gauge noncoring needle for emptying the reservoir and filling the pump (Fig. 16-3)

24-gauge noncoring needles for flushing the catheter access port (Fig. 16-3)

0.22-μ filter (Fig. 16-4)

15-gauge spinal needle (Fig. 16-5)

Intrathecal catheter with a stylet (Fig. 16-5)

Anchor (Fig. 16-6)

Catheter passer (Fig. 16-7)

Minor surgical kit (Fig. 16-8)

Programming device (Fig. 16-9)

Figure 16–1 Various sizes of Tricumed intrathecal pumps (Tricumed Medizintechnik GmbH, Kiel, Germany).

Figure 16–2 Parts of an implantable intrathecal infusion pump.

Figure 16–3 The 24-gauge (left) and 22-gauge (right) noncoring needles used in implantation of an intrathecal infusion pump.

Figure 16–4 A filter and a 22-gauge noncoring needle.

Figure 16–5 A catheter with a stylet (top) and a 15-gauge spinal needle (bottom) for spinal catheterization.

Figure 16–6 Various types of anchors.

Figure 16–7 Parts of a catheter passer.

Figure 16–8 Instruments for a trial of ITDDS. (Intrathecal drug delivery system).

Figure 16–9 Programming device.

Drugs needed for implantation of an intrathecal drug delivery system are as follows:

Lidocaine for local infiltration

10 mg/mL of morphine sulfate (Fig. 16-10) or baclofen

5 mL of preservative-free 0.9% normal saline (for flushing catheter access port when using the SynchroMed II Infusion System pump [Medtronic, Inc., Minneapolis, MN])

Figure 16–10 Package of Highmol (20 mg/2 mL/ampoule)

(BC World Pharmacy Co., Ltd., Seoul, Korea).

Preoperative preparation

Physical examination should include the following actions:

Noting of any entry site infection or skeleton deformity

Recording of relevant laboratory findings

Nonsteroidal anti-inflammatory drug (NSAID), aspirin, and/or anticoagulant therapy should be stopped for 3 to 7 days before and after the procedure.

Patient and caregiver education should be performed as follows:

Instruct the patient on his or her treatment and personal responsibilities.

Explain that if the pump is not explanted at the patient’s death, the pump and alarm should be inactivated.

Explain that if the body is to be cremated, the pump should be explanted to avoid explosion.

The initial dose given by the drug delivery system must be determined according to current pain therapy, as follows:

For a single injection, the initial intrathecal injection should be 0.3 to 0.5 mg of morphine or half the intrathecal equivalent of daily opioid intake.

For multiple bolus injections, a series of intrathecal or epidural injections should be used.

For continuous epidural infusion with a patient-controlled analgesia system, the initial dose should be 0.2 mg/hr of morphine or the epidural equivalent of daily opioid intake; the dose should then be increased every 12 to 24 hours until pain relief is reported.

Procedure

This procedure describes the implantation of a SynchroMed II Infusion System pump (procedure might be slightly different for other products).

Step 1: Pump Preparation

1. Informed consent

2. Check initial pump status (Fig. 16-9):

a. Use a programmer to check current pump status. Ensure that the calibration constant is the same as that shown on the package labeling.

b. Check the pump reservoir volume.

c. Confirm that there are no active alarm events.

3. Empty the pump:

a. Remove the protective cap from the catheter port (Fig. 16-2) by pulling it away. A drop of water will appear from the catheter connector of the pump within 1 to 2 minutes. Leave the protective catheter connector cover off.

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