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Implantable Infusion Pump

Description/Scope

An implantable infusion pump is intended to provide long-term, continuous or intermittent drug infusion. This document addresses the use of implantable infusion pumps.

 

Position Statement

Medically Necessary:

Implantable infusion pumps are considered medically necessary when used to deliver drugs for the treatment of:

• Primary liver cancer (intrahepatic artery injection of chemotherapeutic agents);
• Metastatic colorectal cancer where metastases are limited to the liver (intrahepatic artery injection of chemotherapeutic agents);
• Head/neck cancers (intra-arterial injection of chemotherapeutic agents);
• Severe, refractory spasticity of cerebral or spinal cord origin in patients who are unresponsive to or cannot tolerate oral baclofen (Lioresal®) therapy (intrathecal injection of baclofen).

Permanently implanted intrathecal (intraspinal) infusion pumps for the administration of opiates or non-opiate analgesics, in the treatment of chronic intractable pain, are considered medically necessary when:

1. Used for the treatment of malignant pain (e.g., pain associated with cancer) and all of the following criteria are met:
   1. Strong opioids or other analgesics in adequate doses, with fixed schedule (not PRN) dosing, have failed to relieve pain or intolerable side effects to systemic opioids or other analgesics have developed; and
   2. Life expectancy is greater than three (3) months (less invasive techniques such as external infusion pumps provide comparable pain relief in the short term and are consistent with standard of care); and
   3. Tumor encroachment on the thecal sac has been ruled out by appropriate testing; and
   4. No contraindications to implantation exist such as sepsis or coagulopathy; and
   5. A temporary trial of spinal (epidural or intrathecal) opiates or non-opiate analgesics has been successful as defined by a 50% reduction in pain, prior to permanent implantation.
      
      Note: A temporary trial of intrathecal (intraspinal) infusion pumps used for the treatment of malignant pain is considered medically necessary only when criteria 1-4 above are met.
       
2. Used for the treatment of non-malignant pain (e.g., pain not associated with cancer) with a duration of greater than six (6) months and all of the following criteria are met:
   1. Documentation, in the medical record, of the failure of six (6) months of other conservative treatment modalities (pharmacologic, surgical, psychologic or physical), if appropriate and not contraindicated; and
   2. Intractable pain secondary to a disease state with objective documentation of pathology in the medical record; and
       
   3. Further surgical intervention is not indicated; and
   4. Psychological evaluation has been obtained and evaluation unequivocally states that the pain is not psychologic in origin and that benefit would occur with implantation; and
   5. No contraindications to implantation exist such as sepsis or coagulopathy; and
   6. A temporary trial of spinal (epidural or intrathecal) opiates or non-opiate analgesics has been successful prior to permanent implantation as defined by a 50% reduction in pain and documentation in the medical record of improved function.

      Note: A temporary trial of intrathecal (intraspinal) infusion pumps used for the treatment of non-malignant pain is considered medically necessary only when criteria 1-5 above are met.
       

Note: When an implantable/intrathecal infusion pump is determined to be medically necessary, the supplies necessary for the proper use of the pump are considered medically necessary.

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Investigational and Not Medically Necessary:

Implantable infusion pumps are considered investigational and not medically necessary for the infusion of heparins for thromboembolic disease or antibiotics for osteomyelitis.

All other uses of implantable infusion pumps, including fully implantable insulin pumps, are considered investigational and not medically necessary.

Rationale

The role of opioid therapy in treatment of pain is well established in the medical literature. Individuals who have proven unresponsive to less invasive medical therapy and who require large doses of opioids may be candidates for an implantable delivery system that permits intrathecal administration. This system delivers the opioid directly to the receptors in the spinal cord, allowing smaller doses to be used and thereby minimizing side effects. This position is supported by multiple case control studies.

The use of continuous chemotherapy infusion treatment has been studied for patients with certain types of cancers, including, but not limited to, primary hepatic cancer, metastatic colorectal cancer to the liver, and various head and neck cancers. This method of chemotherapy infusion has been found to improve medical outcomes in select individuals where continuous chemotherapy is believed to be appropriate. The evidence supporting this conclusion includes multiple randomized controlled trials. Prospective randomized trials of individuals with unresectable liver disease have shown that compared to conventional systemic therapy, hepatic artery infusion is associated with an increased tumor response rate.

Implantable pumps for delivery of medication to the intrathecal space have been developed as an alternative to chronic systemic administration for the treatment of spasticity of cerebral or spinal origin. These pumps have been demonstrated in numerous randomized controlled trials to reduce adverse effects such as tolerance, dependency, and neurotoxicity.

The use of implantable pumps for infusion of antithrombotic medications for thromboembolic disease, or for the infusion of antibiotics for osteomyelitis, has not been demonstrated to provide any additional improvement in net health outcomes above standard care with bolus or subcutaneous drug administrations. This therapy does not prevent the occurrence of complications or morbidity nor does it significantly relieve pain over other less invasive treatment methods. The risks involved in the implantation and maintenance of implantable infusion pumps for these conditions is not outweighed by any potential benefits. The evidence supporting this conclusion includes multiple case series studies.

Fully implantable insulin pumps are designed to deliver insulin via intraperitoneal or intravenous routes in a programmed and controlled manner to diabetic patients. However, these pumps have been associated with a high incidence of device malfunction related to catheter obstruction, among other malfunctions. Newer devices are under development that are expected to drastically reduce the problem of catheter obstruction. With additional refinements underway, implantable insulin pumps may eventually prove beneficial in the treatment of insulin dependent diabetic patients. To show benefit, however, additional long-term randomized prospective studies are needed.

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Background/Overview

Implantable Infusion Pumps
Implantable infusion pump use for the delivery of intrathecal (intraspinal) opiates is based on the existence of opioid (narcotic) receptors on the spinal cord to achieve "selective spinal analgesia" (pain relief). Pumps provide for the long-term delivery of opioid (narcotic) medication in the management of malignant (cancer) pain and nonmalignant (non-cancer) pain. Examples of appropriate nonmalignant pain syndromes which may be treated with implantable pumps include "failed back surgery", chronic arachnoiditis, visceral pain syndromes, post herpetic neuralgia, phantom limb pain, spinal cord injuries, peripheral neuropathies and reflex sympathetic dystrophy. A successful temporary trial of spinal opiates is required both to evaluate analgesic responsiveness and to increase the long-term success of the procedure. Individuals must be closely monitored as conversion from high dose oral or systemic opioids to spinally administered opioids will sometimes result in withdrawal symptoms.

Treatment with this therapy should remain a last resort, used only after all other appropriate therapies have failed. A permanently implantable drug-infusion system is not usually appropriate when life expectancy is three months or less; for such patients, external drug infusion systems can appropriately provide spinal analgesia and comparable pain relief.

The implantable infusion pump (IIP) is a drug delivery system that provides continuous infusion of an agent at a constant and precise rate. The purpose of an IIP is to deliver therapeutic levels of a drug directly to a target organ or compartment. It is frequently used to deliver chemotherapy directly to the hepatic artery or superior vena cava.

An IIP is surgically placed in a subcutaneous pocket under the infraclavicular fossa or in the abdominal wall and a catheter is threaded into the desired position. A drug is infused over an extended period of time. The drug reservoir may be refilled as needed by an external needle injection through a self-sealing septum in the IIP. Bacteriostatic water or physiological saline is often used to dilute therapeutic drugs. A heparinized saline solution may also be used during an interruption of drug therapy to maintain catheter patency.

There is a range of totally implanted catheters with implanted reservoirs and manual pumps as well as totally implanted catheters with implanted infusion pumps. Implantable infusion pumps are available in either programmable or non-programmable models, depending on the type of medication delivery required. Programmable pumps are for flexible medication delivery as dose titration and regulation will vary due to the dynamic nature of the patient. Programmable designs facilitate flexible dosing options and precise dose titration over time.

An example of a flexible medication delivery pump is the SynchroMed® electronic pump, manufactured by Medtronic Inc. (Minneapolis, MN, USA). This pump contains a collapsible reservoir that can be filled with 10 to 18 ml of liquid medication and a peristaltic pump that pushes the medication through a bacteriostatic filter and catheter into the spinal canal.

Non-programmable pumps are for fixed rate medication delivery when the dosage is expected to be stable. Possible routes of administration include intravenous, intrahepatic, intra-arterial, subcutaneous, intraperitoneal, intrathecal, epidural, and intraventricular.

An example of a fixed rate pump is the Infusaid Implantable Infusion Pump, manufactured by Arrow International (Reading, PA, USA). One chamber holds the medication and the other, a charging fluid. Once inserted into the abdomen, the pump regulates to the temperature of the body, leading to the expansion of the charging fluid, which pressurizes the medication chamber to push the drug through the catheter.

Fully Implantable Insulin Pumps
At the time of this writing, no implantable insulin pumps have received FDA approval for marketing. The MiniMed® 2000 and MiniMed® 2001 implantable insulin pumps have been granted investigational status and are currently being evaluated in clinical trials.

Intrathecal Infusion Pumps
The intrathecal (IT) catheter is inserted through a needle into the intraspinal space, usually at the lumbar or thoracic level. The other end of the catheter is connected to the pump and then filled with medication. The choice of IT pump depends on the indications for intraspinal therapy, the need for bolus versus continuous infusion, the available support services, cost to the patient, and the patient's general medical condition, ambulatory status and life expectancy.

External programming is used to set the dosage, rate and timing via telemetry to the pump. The pump needs to be refilled every four to eight weeks by percutaneous injection, depending on flow rate, and trained medical, nursing or technical staff must perform the refilling process.

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