Hallo everyone!
I am a pre-reg pharmacist and I'm doing an audit about infusion pumps, particularly on how to match a drug with a suitable pump. Similar to the pump categorization by the MDA the Hammersmith Hospital in London has done a drug risk categorization in 1994 but not updated since. Does anyone know if a similar work hsas been done more recently (or at all) by any other hospital/institution etc?
Regards,
Susanne

I think the document you were referring to is MDA DB 9503 published May 95. This was superceded by DB2003 02 last year, but no longer classifies pumps as "suitable for high risk" etc. Have a look at Appendix 1 of this document for further info

Susanne. Our pharmacy were looking at doing a categorisation of all the drugs a few years ago but surprisingly found that there was no national guidance and were unhappy about "going it alone" on the issue. It sounds like something that would be essential to ensure appropriate administration. The Class A, Class B drugs system doesn't seem to help either, apparently, although it's obviously not my field ! !

It's odd that a system was introduced for the equipment but not for the medication. Have you tried any of the specialist pharmacy Web sites - I'm assuming that there are some !

If you find anything, will you share it with us ?

Susanne

Some of this may help.


http://www.ebme.co.uk/ubb/ultimatebb.php?ubb=get_topic;f=16;t=000012;p=1#000000

Bill

Thanks very much for the links. I tried to work with the new MDA bulletin from may 2003 but struggled with the unspecified terms like "good" long term accuracy etc. I also used the pump evaluation reports of the Bath Institute for Medical Engineering (BIME), which gives figures regarding performance parameters but unfortunatly not always a judgment like "this performance is good". So I could not match the MHRA categories and the BIME results completely. The BIME reports are helpful, though (see nww.mda.nhs.uk/pumpevaluation). I tried to find the older bulletin from 1995, but could not find it. Instead I used categorization parameters by the Department of Health, but they are even older (1990!).At the moment I am trying to contact an engineer in BIME to tell me which categories our pumps fall under. Regarding the drugs I had some information from Hammersmith Hospital.They did an IV Drug categorization to match the pumps and drugs in 1994. They haven't done any up-date since, because their trust only holds category A pumps now anyway. I contacted a pharmacist there and she advised me not to rely on the old data.cNow I prepared a list of drugs and gave it to my more experienced colleagues to ask them which drugs in their opinion are rather high or low risk drugs. But after the new MHRA bulletin it seems to be more important to match the pump with a certain therapy than with a particular drug.If I manage to get some useful information I'll let you know about it.
Susanne

Susanne

Have you spoken to Jim Lefever infusion device specialist at MHRA, he has proved very helpful in the past. I believe that Samantha Tham author of the latest bulletin is no longer at MHRA.

Suzanne,
Are you taking pumping characteristic curves into account as part of your study? At one Hospital i worked at, fast acting (inotropic) drugs were used at very low rates (2ml/hr). If you analyse the infused flow and represent it as a graphical display, some pumps have a smooth flattish line, some pumps are more erratic, and others have square wave. It depends on the type of pump head in the device. I believe using the wrong pump can diminish/alter the effectiveness of the drug. One ITU nurse i spoke to noticed a patients blood pressure was up and down (in a regular pattern) even though they were delivering the correct drug.
When we looked at the pump being used it was delivering 2ml/hr over the hour, but it was up to 100% over or under infusing over a shorter timescale, which became apparent when we looked at the graphical output. It mirrored the patients blood pressure problem and enabled us to stop the use of that pump for certain drugs.

If you have a friendly EBME manager, I would ask him to give you some graphical printouts for different types of infusion devices at low, medium, and high rates.

ps. i haven't voted on your pole because don't really understand the poll.

John/ Susanne

The Short-term accuracy /constancy index you refer to is highlighted in page 53, MDA BD2003(02). http://nww.medical-devices.nhs.uk

APPENDIX 1 Choosing infusion devices according to therapy category.
Information about the technical performance of infusion devices is provided by the MDA Infusion Pump Evaluation programme of the Device Evaluation Service. http://nww.mda.nhs.uk/pumpevaluation

Short-term accuracy
Minute-to-minute variability of flow becomes very important where drugs with short half-lives are being administered. The importance derives from the need to prevent undesirable fluctuation of effect-site concentration of the drug. There is documented evidence that minute-to-minute variability of flow can cause variation of physiological parameters and consequent difficulties in management, in both adults and neonates, where the half-life of the drug is short. Short-term accuracy is expressed by the concept of constancy index. This is the shortest period during the pump's steady-state operation over which measurement of output consistently falls within ±10% of the mean rate. The data are derived from the flow tests performed over 24 hours at 1ml/h. Flow is recorded at 30 second intervals over the final 18 hour period. And the average rate compared with flow over each short period. The principle is that the constancy index of the pump should be less than or equal to the half-life of the drug used. Syringe pumps have a shorter constancy index than volumetric pumps i.e. a low constancy index indicates good short-term flow rate accuracy. Battery operated ambulatory pumps frequently have a constancy index in excess of 31 minutes making these particular devices unsuitable for use with short half-life drugs. For the purposes of this bulletin the half-life of a drug is the time taken for the concentration of that drug to be reduced by 50 % either by metabolism or excretion.

Notes
1. The half-life of a drug cannot usually be specified precisely, and may vary from patient to patient. As a rough guide, drugs with half-lives of the order of five minutes or less might be regarded as "short' half-life drugs.

2. Diamorphine is a special case. The injected agent (diamorphine) has a short half-life, whilst the active agent (the metabolite) has a very long half-life. It is safe to use a device with performance specifications appropriate to the half-life of the metabolite.


Bill

Susanne
How did you get on with your categorisation? I would be interested to know. I was much involved with the discussions at MHRA that led to the rescinding of the old categories and the development of the new. I can give you some insight into what is meant by "good" accuracy if you want to phone me. Or Email me at BIME. My email address and telephone number is on our website and in our reports.

Teresa Dunn, MHRA Infusion device Centre.

Susanne

You said your looking at matching drugs to suitable pumps.
Would this include looking at what drugs can be given by gravity as opposed to using a pump?
I run an Equipment Library and have noticed over the past few years that people seem to use a pump automaticly when a patient has an IV and not necessarily because whats being infused or the patients condition requires it. Reasons for using them seem to be because its easier, especially if they are busy while other people think its policy to use them all the time.
Unfortunatly this means we often run out of pumps and either need to turn people away or have to scourer the wards questioning staff as to why they are using a pump.
Do you or anyone else have any thoughts on the matter?

Teresa et al,
I have emailed the MHRA with this question and have had no reply and wondered if anyone else could answer it.
Who decides on the catagorisation of pumps?
Do the manufacturers declare it or do the testers such as BIME define it?
There is a pump from a well known manufacturer that has just high, medium and low pressure alarms but is declared as a pump suitable for neonates/high risk, I would query this with such coarse alarms.
Obviously the manufacturers want to have pumps rated at the highest safety category so might stretch the boundries.
Any comments?
Robert