EBME Forums Forums Maintenance Technical Assistance Bodyguard 575 Pumps

HI we had a case where one of these pumps underinfused by 50% approx. i.e. there was 54mL of fluid left in the bag from a 100mL bag after the pump said it had finished infusing. When I tested it it ran fine for a few hours them it did begin to slowly underinfuse and by the following morning each bolus was not delivering anything but the pump was logging that it had infused the full 2mL per bolus. However since then and trying other infusion sets it has never played up at all.

I think it may have been a dud or faulty infusion set as it has not occurred since. But I would be interested to hear from anyone who may have had a similiar experience.

Thanks
Mike

Almost certainly the set.

These little pumps are usually quite accurate if they are set up correctly to the type of set being used. But it's no good chopping and changing the sets. That is, stick to one trusted type.

HI Geoff and thanks for the reply. all sets came from the pump manufacturer, they have 2 diferent ones that they colour code differently (though apparently the same).

One with blue stripe for PCA and the other Yellow stripe for Epidural. I ttried 2 sets both same batch from our ICU on 2 different pumps and they played up. i.e. Underinfused over time, they were always fine when started but began to under infuse later after a few hours. It was really strange and I have since tried to deliberatly set them up incorrectly i.e. insert a twist in the part crossing the pumping fingers and even that does not cvause any problems. I have tried partially occluding the set near the bag but either it delivers the full bolus or alarms an Air/Upstream alarm.

The strange thing is that since we had the pump returned I have tried one of the sets that underinfused (and after I added a dye to the saline going through the pump, you could see the liquid surging up and back inside the set, like it was trying to pump one way then the other, I have movies of it happening) and it runs fine now witout any probs! And it occurred on 2 pumps with 3 different sets.

Again thanks for your reply.

Cheers
Mike

Interesting! Sounds like to just need to keep an eye on the situation.

What state is the camshaft in, I wonder? Smooth, clean (dry)? Do you lubricate them at all? My other thought is about the door (pressure bar springs) ... but you're saying that it's all OK for a few hours initially.

But I would still suspect the set(s) myself.

But when you think about it, it's a wonder that pumps without a drop sensor are accurate at all, especially over time!

As I have mentioned before, in the "perfectly designed pump", all the sensing would (should) be done as close to the infusion site as possible. That is, what is actually being delivered (and at what pressure), and then applying feedback. Rather than by counting camshaft revolutions with an optical encoder (or whatever).

Thanks Geoff, yes need to keep an eye out. THe pumps are all new and I do not wish to strip them down as they have tamper detection "Warrenty Void" stickers on them all at present. I agree with you re where dose measuring should be done, the sets have a Y joiner near the distal end and who knows perhaps if you put another pump onto that at a pretty high flow rate it could potentially interfere with the PCA dosing. Though the 575's seem to infuse their small doses at a very high flow rate.

Again thanks for your replies and I will keep an eye out for sure.
Cheers Mike

Did you keep the batch number of the set? Maybe worth reporting....

The Mckinley pumps are usually pretty spot on. We have had them for 6 years now :-)

HI Biff thanks for the reply, yes did have the batch number, but have had the fault occur with 2 sets from the batch yet others fine. So unless there was a few dodgy sets in the batch I dont know.

When I tested the very first new set with the suspect pump, it ran fine, spot on 2 mL every time until I put a needle on the end to try to simulate the amount of back pressure that a central line might have generated. I put a 20 gauge needle on with gave me a pressure of around 18mmHg in the set. And that is when the first pump/set began playing up immediatly and delivering very small bolus's. But with another pump / set the needle made little difference it just began playing up after about 16 hours, even though it had not infused that much during that time. So yes it is pretty mysterious!!

2 very experienced nurses saw it happen once and in my testing I have seen it occur twice on two different pumps with 2 different (though same batch) sets. A real head scratcher!