EBME Forums Forums Maintenance Technical Assistance Excessive condensation in the circle system

Can anyone help
We are having problems with condensation building up in the patient circuit when using the circle system with low flows for long cases.We are also using a HME filter at the patient end of the system.We are currently trailing a new circle system with a built in heater but are still experiencing the same problem. Has anyone else experienced this problem and reached a solution.

There's bound to be condensation (rainout) (it's the laws of physics). Isn't there a water trap in there somewhere (or am I missing something here)? Do you have details of the set you are using (supplier, catalogue number, etc.)?

I assume (should I ever assume .... but you're using the phrase long cases) that you're referring to anaesthesia here KAG, rather than ICU?

I also hear the term exhaled breath condensate (EBC) being used. Is that what we are talking about?

HME: hygroscopic heat-moisture exchanger? I always thought these should not be used in anaesthesia circuits (?)

Meanwhile, here's a link for anyone else who may be interested.

Hi Geoff
We have the penlon SP Prema. Yes we are talking about long surgical casees.
Intersurgical circuit and HME Filter at the patient end. The circle system has a water trap but it have little water in it, in these long cases. The water is building up and pooling in the anaesthetic circuit limbs. Would I be right in thinking the HME filter is exacerbating the problem and we would be better off using just a bacterial filter
Thanks

I would try removing the HME altogether. As I say, I believe they should not be used during anaesthesia at all (but I'm no expert). Don't they impede the flow of anaesthetic gases? Anybody ... ?

Sounds about right.

I'm no expert but on the ICU's we considered that if the circuit was wet then we could just use a bacterial filter.
Rain out was a common problem with vent circuits on ICU patients.
Regular water trap emptying seemed to help as did checking that temp probes were seated correctly and the limb wire set to 1-1.5 oC above the heating chamber temp. Sounds simple but have the users read the manual and understood it. Based on personal experience people used to make things up as they went along with hunidifiers. Usually found incorrect settings when trouble shooting. Dr settings as opposed to manufacturer settings

Indeed, but we need to be careful here (do we not?). "Long-term" ventilation in the ICU, and "long cases" in the Theatres are two different sets of circumstances, right? One uses anaesthetic gases, the other does not. How long are these cases, KAG? Just how many hours are we talking about here?

We are talking about 4-6 hours nothing like ICU cases.
The soda lime is damp but not saturated. This problem is not experienced with shorter cases and like i say the water trap has very little water in.

Sorry to be a pain, KAG, but I think you're going to have to describe the complete circuit for us! Fresh gas outlet -> then what? Or should I say absorber outlet to patient -> then what? Where, exactly, do you place the HME (at the mouth-piece)? Does the patient inhale, and exhale, through it ... or what? Where exactly do you place the water trap (at the lowest point of the return circuit)? Sorry, but we need input!

No problem thanks for your help.
The water trap is beneth the circle system soda lime jar. The HME Filter is at the patient end of the respiratory circuit so the patient breaths in and out through the filter.

And where exactly is the excessive moisture build-up collecting (you're saying that it's building up and pooling in the anaesthetic circuit limbs, but not in the water trap)?

Meanwhile, any clues here? Or, perhaps, here?

As I say, I'm certainly no expert, but I would have thought that your patients could manage OK without an HME for the period of time you mention. I think I would try using just a normal breathing filter.