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Morphine Pump

Leon Retief leonr at iafrica.com
Fri Jan 19 14:09:24 EST 1996


In article <4dgv1d$50m at ixnews8.ix.netcom.com> phnxbmed at ix.netcom.com(Charles Hokanson ) writes:
>From: phnxbmed at ix.netcom.com(Charles Hokanson )
>Subject: Re: Morphine Pump
>Date: 16 Jan 1996 19:41:33 GMT

>In <30FAADB2.315B at invitrogen.com> rbennett at invitrogen.com writes: 
>>
>>Does anyone have information about morphine pumps?  How long have 
>>they been used for?  What complications can arise, etc.?  Someone 
>>very close to me may need one and I just need more information.  
>>References from medical journals would be a great help, too.  Thanks 
>>for your trouble in advance.


>There are both internal and external pumps which are used to administer
>various medications, including morphine.  Generally morphine, when
>administered intervnously through a pump is for a terminal patient.
>Unfortunatley, the amount of morphine required to control pain in
>terminal cancer patients frequently impairs the patient (they get doped
>up).  However this is preferable to the pain.

>In europe, rather than intervenous administration of morphine, the drug
>is frequently administered via needle and syringe through an
>implantable port accessing either the intrathecal space or the
>ventricles of the brain.  The advantage to this technique is that
>1/10th the dosage can be used to control pain, and the patient is not
>impaired.  The patients family is taught to administer the injection,
>so it can be done inexpensively at home.

>Regretably, medicine as practised in the US is driven by $$$$$. 
>Infusion therapy is BIG business, taking a large chunk out of medicare
>dollars.  There is a financial disincentive for doctors and clinics to
>switch to intarthecal or intraventricular administration.  So don't
>hold your breath trying to find this form of treatment here in the
>states.  

Morphine by & large acts on 2 sites as far as pain relief is concerned : the 
spinal cord, where cerebral activity is not affected, & the brain, where 
cerebral activity is suppressed. If morphine is given by intrahecal injection, 
it will soon enter the cerebral matter because morphine "likes" the brain & 
moves there. If given by intraventricular injection, it of course is already 
there. If given by iv or im injection, much of it dissipates into the rest of 
the body & a small amount only ends up in the brain where, like intrathecal & 
intraventricular injections, it causes pain relief. If the dosage has been 
correctly adjusted for the patient's needs, iv or im injection will not "dope" 
the patient more than intrathecal or intraventricular injections - see below.

Morphine in general may cause respiratory depression because of its central 
(i.e. brain) action. Intrathecal & intraventricular administration is a 
method well know for causing this complication. Because of this a patient 
receiving this method of pain control must first spend some time in hospital 
to have his/her dose adjusted & so that reaction to the drug can be assessed. 
One must also bear in mind that patients suffering from malignancies tend to 
develop higher morphine requirements as time goes by & that the family, in an 
attempt to relieve the recurrence of severe pain, may inadvertently increase 
the dose too much, so causing respiratory arrest. 

I am rather wary of indwelling intrathecal or intraventricular catheters. Such 
devices are, IMHO, too prone to infection if left in situ for more than a few 
days, & the results of an infected catheter in the intrathecal space or the 
ventricle is rather bad.


Pain pumps may be taken home & an opiate given thru a heparin port, an short 
cannula in a vein, containing a small amount of the anticoagulant heparin, 
which keeps the blood from clotting & therefore the cannula does not have to 
be changed too often. Morphine may also be given via a pain pump thru a 
cannula under the skin or into a suitable muscle - in both cases thru an 
indwelling cannula..

Oral morphine is another possibility, although if the patient is nauseaous it 
should not be used. Up to 1 g may be given every 4 hrs. It is not true that 
morphine will always "dope" patients - if the dose is tailored to fit his/her 
needs, then quite often there will be little or no cerebral depression. It 
takes some days to achieve this, though.

Another possibility is transdermal fentanyl patches. Fentanyl is a "cousin" of 
morphine & these patches are made by Janssens Pharmaceuticals - and no, I have 
absolutely no connection with them whatsoever. They look rather like plaster & 
are available in 3 strengths. A problem is that the 1st patch takes about 24 
hrs to take effect, so morphine cover must be given. Again, the dose must be 
tailored to fit the patient's needs - more than 1 patch or strength may be 
used. A patch usually lasts for 72 hrs & if a replacement patch is applied in 
time there should be no painful interval. I must admit to little personal 
experience about these patches myself, but my oncologist colleagues say they 
work just fine.

There used to be simple, cheap pumps, some even without a battery. I don't 
know where in the USA you should ask - perhaps there is a pain clinic near 
you? 
Regards,
Leon Retief, Cape Town.



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