Design help needed - Isoflurane compatibility with polymers - Anesthesia gas

[45fan]

Apologize for off-topic thread. I don't know where else to go. I can't find enough info anywhere, including manufacturers, about material compatibility of isoflurane, an anesthesia gas, so I thought maybe some of my friends here on the QA board might know something.

I need information on polymers that will not degrade in the presence of, or absorb too much, isoflurane. I would like to use a flexible material, such as EPDM, polyurethane, a perfluoroelastomer, or silicone compound for a seal. Problem is, there is very little published information about the subject and the suppliers of isoflurane won't give out any info, and the polymer companies aren't much help. The only thing I've been told is that Teflon works. I don't want to use Teflon and am not ready to have a composite seal made that has a flexible substrate coated with Teflon.

Any help of any kind would be greatly appreciated.

Tom Loebig

 

[Al Rosen]

Apologize for off-topic thread. I don't know where else to go. I can't find enough info anywhere, including manufacturers, about material compatibility of isoflurane, an anesthesia gas, so I thought maybe some of my friends here on the QA board might know something.

I need information on polymers that will not degrade in the presence of, or absorb too much, isoflurane. I would like to use a flexible material, such as EPDM, polyurethane, a perfluoroelastomer, or silicone compound for a seal. Problem is, there is very little published information about the subject and the suppliers of isoflurane won't give out any info, and the polymer companies aren't much help. The only thing I've been told is that Teflon works. I don't want to use Teflon and am not ready to have a composite seal made that has a flexible substrate coated with Teflon.

Any help of any kind would be greatly appreciated.

Tom Loebig

Would this paper, Diffusion of anaesthetic gases through different polymers, be any help?

 

[45fan]

Thank you Al.

Looks like I can rule out silicone with that article. Funny how I missed that one when I did a Medline search yesterday. I pulled 10 articles down that didn't have that information. Now if I could just find some solubility and diffusibility data for isoflurane in other materials.

You wouldn't happen to know someone at an oxygenator or pump company that has studied any of this, would you?

 

[Al Rosen]

Thank you Al.

Looks like I can rule out silicone with that article. Funny how I missed that one when I did a Medline search yesterday. I pulled 10 articles down that didn't have that information. Now if I could just find some solubility and diffusibility data for isoflurane in other materials.

You wouldn't happen to know someone at an oxygenator or pump company that has studied any of this, would you?

Can you derive the information from this data sheet?

 

[45fan]

The pieces are starting to come together. If I understand the partition coefficient correctly, I now have the solubility information that I need. Together with the article from Medline that you referenced, along with some others that I found, I'm making some serious headway! If I understand the problem, I need solubility, which I have from the data sheet, diffusibility, I have some from Medline articles, and last I need a measure of degradation. That is a little harder to come by, but I'll find it one way or the other.

Thanks again.

 

[Al Rosen]

The pieces are starting to come together. If I understand the partition coefficient correctly, I now have the solubility information that I need. Together with the article from Medline that you referenced, along with some others that I found, I'm making some serious headway! If I understand the problem, I need solubility, which I have from the data sheet, diffusibility, I have some from Medline articles, and last I need a measure of degradation. That is a little harder to come by, but I'll find it one way or the other.

Thanks again.

Would the degradation be dependent upon all the different elements in your system and validation of your system resolve this issue?

 

[45fan]

Short answer, yes. We plan to fully test and validate any materials that we choose.

What we are really after right now is a material for a prototype other than Teflon that will stand up to isoflurane and not absorb or diffuse much of it over about a 1 week period. Anything chosen for long term solutions would be fully validated. In fact, we know that we can use Calres, a perfluoroelastomer, becuase it is used in valves that we bought for the application. But this stuff, I've been told, is expensive and hard to get, and I don't know whether it comes in a readily moldable form. We can get it in sheet form, but it will be difficult to reliably cut the shape that we need. These are the reasons why I've been trying to track down info on any elastic seal materials. It looks like polyurethane is a good candidate, but there are many formulations of pu so I'm spending my time bugging people like you and anyone else I can think of while I wait to see if the darned isoflurane and plastics manufacturers will return my calls and give me some useful info.

Have a nice day and thanks again.