Pain Management Center

Vero Beach, Florida

INFUSION PUMP

The Benefits and Side Effects of Infusion Pump

H. Hooshmand, M.D.
Neurological Associate Pain Management Center
1255 37th Street, Suite B
Vero Beach, FL 32960

The philosophy regarding infusion pumps is as follows:

The infusion pump provides a steady flow of Morphine or Dilaudid into the spinal fluid to help manage the severe chronic pain, which has not responded to the standard treatments. The infusion pump is only effective if the patient limits the intake of pain medications to only through the pump administering medication in the spinal fluid.

Because the Morphine or Dilaudid has a higher specific gravity than the spinal fluid, the infusion of such medications (definitely not together) into the spinal fluid provides mainly pain relief in the lumbar spine and lower extremities. This is because when the patient sits up or stands up the pain medication precipitates in the lowest part of the lumbosacral cannel. So, the infusion pump is most effective for injuries from the waist down. Such conditions as severe knee injury, lumbar spine injury, arachnoiditis, failed back syndrome, CRPS (RSD) in the lower extremities, all have the potential of having better than 80% pain relief.

Such pain relief cannot be achieved unless the following precautions are applied:

The therapeutic dosage of Morphine in the spinal fluid is anywhere from 3.5mg up to 15.5mg. The therapeutic dosage of Dilaudid is anywhere from 2.6mg up to 8.5mg. If either of these medications is even in a very small amount below the lower limit of therapeutic dosage or above the highest limits of a therapeutic dosage, then the patient will have severe pain. The reason the higher dosage of narcotics causes such severe pain is because of the fact that Morphine or Dilaudid has the tendency to saturate the three endorphin opioid receptors. These are: mu, kappa, and theta receptors. The kappa receptor is the largest of the three. If these medications mentioned above are given in the therapeutic dose, then there is still room for the kappa receptor to receive endorphin secreted in the central nervous system. On the other hand, if the above therapeutic dosages of narcotics are applied, then all the three receptors will be flooded with narcotic and the patient will have severe tolerance and withdrawal pain because of the lack of secretion of the endorphin. The central nervous system is not going to produce and secrete endorphin if the patient is already on large and supratherapeutic doses of such medications.

The rate of success of the insertion of the infusion pump at the beginning is no more than 80%. With the passage of time, because the patient and doctor become impatient, and apply narcotics through other routes, then the rate of success drops to less than 40%.

Because the doctors have a tendency to be extremely generous and treat the patient with multiple narcotics such as Duragesic, applied simultaneously with MS Contin, Oxycontin, Methadone, Morphine, etc. the patient not only is in danger of overdose and respiratory arrest, but also the patient will have more severe pain than if he was not on the pump. This is the main reason we see more and more of the pumps being turned off because of the problems mentioned above.

It takes at least 4-6 months to get the pump installed and going.

Even after making sure that the dosage of medication is no sub- or supratherapuetic, still it is important to watch out for other side effects of the narcotics in the spinal fluid. The commonest side effect is a marked edema in the extremities, especially in the lower extremities. This edema is due to suppression of endogenous estrogen in women and endogenous testosterone in men. So, the treatment should be supplemented by providing enough estrogen or enough testosterone to prevent the edema.

Another main reason for failure of the pump is the fact that the patients don’t understand the importance of being very selective and conservative in regards to the pain medications, and as a result while the pump is being tested, installed, and the medication is being gradually increased in dosage, the patient sneaks another narcotic from any of the relatives, friends, etc. Once the patient starts taking the new narcotic medication, then the pump completely fails.

Finally, there is another serious problem with the pump in that there have been more tendencies for under supplying the pump with pain medication rather than oversupplying it. We have seen patients who have been tried on 1mg or 2mg Morphine or Dilaudid for several months, sometimes more than a year, with no relief of pain only because the medication has not been raised up to the therapeutic range.

If the doctor in charge of the pump is meticulous, careful, and selective, and if he does not add other types of narcotics, then the results for pain in the lumbosacral regions and lower extremities are excellent.

If the pain is originating from the central nervous system, or from the cervico-thoracic regions, not much can be expected in regard to benefit of the pump for pain relief.

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Eric M. Phillips; E-mail: EricmP9512@aol.com

This page was last updated on 1/19/2005.