Can I put this one up again?

We have now had 6 cases of air bubbles found in blood infusions, the biggest bubble was 12mm long which is less than 0.2mL, they have occurred in two different departments, with different giving set batches and different ages of Graseby 500 pump. The rest of the details are the same as in the first post.

The second department assured me that they had never had this problem until I pointed out an infusion they were running had a 10mm bubble in it.

I still think that it’s a build up of the gas that is being produced as the blood warms up (champagne bubbles). But I need some kind of evidence to present to our risk management people to assure them that it is safe to use, still waiting for Graseby or the MRHA to come back with something.

A friend of this site has recommended that the staff give an extra squeeze to the drip chamber but the staff say that “that is not what it says in the instructions” and that they will not be able to use the chamber to check for drips.

Has any one else got this happening? Any more suggestions?

Help……………

Lee

Hi Lee

I can see this is going to go on for a while. I recon that since you have made people aware, they are looking for and found instances where this is occurring. Most staff tend to set up a pump and if it runs for a few minutes or so with out alarming they walk off to do something else and don't tend to notice anthing out of the ordinary unless the "bing bing bong" goes off.

I'm not sure about the gas build up bit.... I wouldn't have thought that much gas could be suspended by fluid in normal atmospheric pressure.

Hi Rich

If I am right then most of the gas would appear after the pump (as this is a much longer pipe run) and some of this gas is collecting at a high spot (normally between the cannula and the area where the tube is stuck to the patients arm). This gas could be the accumulation of all that available from 250mL of blood, I don’t know how much gas could be expected as the blood warms up from about 5 degrees centigrade up towards room temperature, but I am looking at between 0.1ml to 0.3ml if you add up the larger bubbles.

Does anyone know of any devices to remove or trap air in the market that could be put between the Graseby giving set and the cannula?

Lee

Hi Lee

I can see where you're comming from as the length of the tubing could be basically an air fluid seperator. The only thing that comes to mind here is that the air should be seperating in the tubing from the cassette to the bag and in the cassett itself. By this time most of the air should have dissapeared up line.

It's the sheer volume of air which I can't get my head around and the scenario we had when the pump just carried on pumping air and fluid because the cassett became stained.

Two things to point out, blood tends to have more dissolved gas than a normal fluid such as saline because that is one of its functions. Therefore there will be more outgassing occuring due to warming up to room temperature.
Secondly, I am not aware of any end point filter that can be used with blood to trap air, neither is there a bubble trap available.

Maybe there are two seperate scenarios here

1. The longest part of the tubing which extracts heat from the environment, warms up the blood which subsequently off gassses.

2. Staining of the casette which presents an IR block subsequently disabling the AIR IN CASSETTE alarm.

I don't think the problem we have is the same as the one you've seen with the staining Rich. We are not seeing the volumme of gas that would be required for some of it to be pumped through the set.

Lee