Nitrogen... at what depth?

[shurite7]

I'm asking relation to "don't dive when pregnant rule". I know that is a debatable subject and many people do but the scientific reason is that nitrogen in the blood has affect a Feotus. However if there is a net loss of nitrogen below 6m then one would assume a pregnant person can do shallow dives up to 6m without risk.

I'm looking for a scientific discussion, not comments like "would you risk it" or "it's not your like your messing with".

Years ago, during my undergrad, I wrote a research paper on diving and pregnancy. During my research I found some interesting data that was conducted in retrospect. One of the factors that most people don't think of is the chamber ride (in the case of DCS) and the administration of O2 during treatment. A fetus is highly susceptible to high concentrations of oxygen. Too much exposure can lead to blindness.

 

[WetSEAL]

Does the fetus know about the dangers of holding it's breath while the mother is ascending?

 

[doctormike]

There are air/gas pockets in the foetus that cannot be equalised, so they get crushed.

I'm not an OB/GYN, but from what I know there is not supposed to be any gas in a fetus. In fact, intrafetal gas is a pathognomonic (google it) indication of fetal death.

 

[JamesBon92007]

A few years ago I was diving with a obstetrician who summed up the dangers of diving while pregnant as something along the lines of, "we know enough to say once you know you're pregnant you shouldn't risk it".
My understanding is that it's the pressure, not nitrogen that is the issue. If nitrogen were the only problem it could be solved by diving with a rich nitrox mix. That is not the case. There are air/gas pockets in the foetus that cannot be equalised, so they get crushed.

This makes me wonder if it's safe for a pregnant woman to dive down to the bottom of a swimming pool. I've never heard that this might be a danger. If I remember correctly (it's been a while) swimming is generally considered good exercise during pregnancy. I don't know of these "air/gas pockets" that you refer to since the embryo grew from conception in liquid and breathes only liquid. Are we somehow made with empty sinuses?

The studies on animals in hyperbaric chambers have not been very positive. No doubt there have been many cases where women went diving, not yet knowing they were pregnant. Here is a thread about the subject:

Diving While Unaware of Pregnancy

 

[BoltSnap]

Why chance it especially when no one knows anything for sure??

 

[eelnoraa]

Why chance it especially when no one knows anything for sure??

Exactly, just don't risk it.

To OP, just imagine, for whatever smaller probability there is, what if you fall on the wrong side side, can you live with the consequences. And don't just think about yourself, think about the baby and his/her life ahead. Just wait 9 months, then you can resume.

 

[stuartv]

yes for air, no for EANx, when EAD is >0 *i.e. ppN2 is great than .79* then you will be ongassing, but if EAD<0 *which it is at some range of depths for all nitrox mixes when ppN2 is less than .79*, then you will be offgassing or neutral.
i.e. EAN51 above has a ppN2 of .79 at 20ft/6m/1.6ata so there is no inert gas pressure gradient in the tissues. EAN32 is 5.3ft/1.6m/1.16ata
anything shallower than those depths you'll be offgasing, albeit slowly

This is the Basic forum. I was referring to recreational Nitrox. I.e. 40% or less.

 

[Ghost95]

Theoretically speaking, would it be possible to get bent while diving to 5 or 6m albeit for a very long time? Or is there not a large enough pressure gradient for gas to come out of solution fast enough to cause bubbles when ascending from that depth regardless of the tissue load?

 

[tbone1004]

Theoretically speaking, would it be possible to get bent while diving to 5 or 6m albeit for a very long time? Or is there not a large enough pressure gradient for gas to come out of solution fast enough to cause bubbles when ascending from that depth regardless of the tissue load?

not enough pressure gradient for it to matter

@stuartv even less than 40% they all have some depth associated with offgasing due to ppN2 being less than surface air, it's just shallow end of the swimming pool vs. deep end of the swimming pool

 

[elmo]

I'm not an OB/GYN, but from what I know there is not supposed to be any gas in a fetus. In fact, intrafetal gas is a pathognomonic (google it) indication of fetal death.

You may not be an ob/gyn but I dare say you know more about foetal development than I do. I'll happily stand corrected.