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IVF > IVF Mail
CO2 % at high altitudes |
By:
Dr.Sowmya Dinesh, Santasa Hassan IVF & EndoSurgery Institute
07 July 2009
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Hello! My centre is at a higher altitude around 900 metres above sea level.I need to set the CO2 at 7.8 to 8% to get the Cook media at 7.30 -7.33. I have a senitive,calibrated pH meter (which mesures +/- 0.01) and a digital capnometer calibrated with 5% CO2.This looks quite strange but logical as we need higher co2 % to generate the required PCO2.I need to raise the CO2 by almost 1% to get 0.3 drop in the pH.So I may need to make it more than 8 % if I aim the pH to be around 7.27 - 7.30. Is there any one who is using similar concentration... .Can anyone in similar situation guide me? Thanks in advance - Sowmya |
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Reply to Michael Reed
Sowmya Dinesh said on 15 July 2009
"Dear Michael Reed,Thaks so much.You have touched many finer aspects of the lab physiology!I am using Cook media which aleready has protein.One of my incubator has infrared and the another requires humidity.My place may differ from yours in terms of high humidity.I didnt think that humidity may have a significant role.I'l look into it.I am waiting for the result with last batch of media(8 cases) before deciding to try with a newer one.As Dr Ahmad Omar pointed out growing to blast stage is a good idea.But cant you predict the incubator performance with grades of D2 embryos? Regards"
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Thanks for the replies .. few more queries..!
Sowmya Dinesh said on 15 July 2009
"Hi! This is my feedback after changing my icubator settings.I had an excellent fert and cleav rate (One woman having 20 0ut of 20 grade1/2 D2 embryos).I am awaiting the hCG values in another 10 days.
Considering the fact that even labs at higher altitudes than mine are requiring around 6-7%Co2 I think I really need to re evaluate the incubators once more.
But one more fact is that the present climate around here is very cloudy,cold with continuous drizzle throught the day.I really need to know what is the relation of humidity to co2% and whats the accurate method of measuring humidity.Thanks for the replies."
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thanks reeds
alok teotia said on 13 July 2009
"Thank you REEDS for the vital information, i feel this angle is missed by few of embryologists, particularly those settelled at ground level."
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Is it the CO2 % or the PH
Dr.Ahmad Mohamed Omar said on 13 July 2009
"It is really interesting how several factors might affect embryo development.
I think that maintaining Ph at 7.23 to 7.27 regardless the Co2 level is the answer. provided that you are applying other quality control measures and accurate Ph readings.
Another important factor is the pattern of embryo development in your incubator, which you can observe by dividing the injected oocytes over two incubators one with the old setting and the other with the new setting; surplus embryos development to blastocyst in any of the tested incubator will be the golden key to your answer.
Good luck"
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co2 at high altitude
Dr.RINKU BANERJI said on 11 July 2009
"whatever is the required level of co2 u maintain pH of droplet ie. 7.25-7.27.I think my embryos are happy with this pH rather than the level of co2"
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CO2 and altitude
Michael L. Reed said on 09 July 2009
"Interesting question - altitude does play a role in the partial pressure of CO2 needed to maintain a certain pH, however I think in you case, there might a factor other than altitude contributing to the problem.
My lab is at approximately 6000 feet above sea level, essentially twice the altitude that you have described, 900 meters, and I maintain a pH of around 7.2, using either Global or G media, with approximately 6% CO2. In theory, I would need slightly higher CO2 % than you to maintain the same pH. To the other extreme, we have an IVF colleague in Peru at around 10,000 feet above sea level, and the CO2 % required for similar pH is about 9%.
What protein supplementation are you using? Are your readings with or without protein?
And...what is your local humidity, and do you have CO2 sensors that are dependent upon humidity, rather than infrared? My lab has extremely low humidity, around 6 to 10% on average, and I keep two large pans of water in each incubator. I know that if I let the water levels drop, the sensors do not read correctly. A basic principle, and the incubator manufacturers may not always take that into account with their manuals. You may follow the incubator directions and still not have enough humidity to get proper sensor function.
If that does not solve the problem, then look to other media from a different vendor as a control - most media today are designed to operate at similar pH with either 5 or 6% CO2.
Good luck!"
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