IVF Mail - Gas Concentrations in Trigas Incubators used in IVF

Gas Concentrations in Trigas Incubators used in IVF

By: Noreen, LMDC
07 November 2008


Question:
	These days trigas incubators are being marketed with success. Will somebody explain me the concentration of CO2, O2 and N2 in these incubators in IVF programmes? Furthermore I would also like to know if they are superior to those using the pre-mixed air.

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kersi m avari said on 09 November 2008

"as regards the triple gas mixtures we are totally at the mercy of suppliers. It on their assurance that we have to depend on. In a certain brand of incubators which strictly demand the triple gas mixtures, it would be like gambling with our IVF cycles. Though at times luck favours the brave but in two very prestigious labs in India, the results came crashing down thanks to the triple gas mixtures. Instead of us jumping into the mol bio and physico chemical jargon, we should nip the problem in the bud, else our 5 or6% co2 are ideal."

Michael L. Reed said on 07 November 2008

"Ok, incubators part two. This is a great question as well. There are several methods used to get to 'triple' mix incubation.

Incubators that use nitrogen to purge the atmosphere to control O2, concomitant to injection of CO2, use a whole lot of nitrogen. This is one of the downside aspects of triple mix incubators. Nitrogen can be delivered to the incubator from either a nitrogen generator system, from standard pressurized gas cylinders, or from the vapor bleedoff of pressurized liquid nitrogen storage tanks.

The upside to this type of system is the extreme flexibility, where you can set whatever triple mix you want to meet low O2 and CO2 needs.

And, there are folks that are using less nitrogen by reducing O2 to one-half atmospheric levels (10%), rather than working at one fourth atmospheric levels (5%). Reducing O2 is a good thing, and balancing O2 reduction against nitrogen use something each lab can determine for themselves.

Another system is to use 'pre-mixed' pressurized cylinders that are filled by weight and analyzed by gas chromatography. This gas mix is not flexible, in that you can only have one mix per tank. Using this type of mix for continuous flow through a small incubator chamber uses a lot of gas, however if you use small sealable enclosures, e.g. a glass desiccator jar or a Billups-Rothberg style chamber, you can conserve gas quite nicely. The other downside to using small chambers is that they take up a bit more room in an incubator. I use glass jars myself, and I can fit three jars in a standard incubator, where one patient is placed in each jar. This is also good to eliminate door opening issues, as no matter how many times the incubator door is opened, the sealed jars protect the embryos from change. Another benefit to using a pre-mixed gas is that you have a very consistent product within a cylinder - no variations to worry about, and you have a very clean product that is not vuneralbe to envrironmental conditions.

Mike"