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Blood spitting.

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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Well-Known Member
Jun 19, 2002
Later note...

Geez I must have been sleeping when I added this post and did not see the same topic two posts below... If somebody wants to move it under the other "blood spitting" thread, feel free.

Original note...

The other day I spit a little blood for the first time, after a diving
session. The deepest I went was about 27m and I did something
like 68 dives. Mostly shallow playing with crayfish at 3-8m. I
ended the day following the line of a buoy down to 18m.

Now theoretically we have spoke about thoracic filling occuring as a prevention mechanism from over-compressing the lungs. However I don't think I went over my residual lung volume by any significant amount. Generally I go deeper than 27m one after the other and have never experienced the blood spitting on these days.

It occurs to me that it may be taking place in part as a diving

However, I just thought of something as I am writing this... I know somebody else was having trouble with the squeeze and was spitting blood around, or just after 20m. Yet if they did free immersion they could seem to reach 30m before the same occurence. Now if I think about my dives, I can recall that I was not in a very relaxed state and was diving quite regularly without the usual preparation. This leads me to wonder if in the process of holding my air in, dealing with contractions, and working a little more intensely on equalizing, that I may have been tensing my diaphram which would lead to the lungs being held open a lot sooner. In turn creating the vacuum that would draw the blood into the lungs.

That being said, I do not recall the feeling I normally receive at
around 40m where I have gone past my residual volume and a vacuum is created that if I do not anticipate, sucks my face and mask up like I just bit into a lemon thinking it was an orange. That is not to say that it did not occur, because I have also been dealing with that problem and not experiencing it always.

Well just thought I would share the issue and maybe get some other takes on it. I am sure there are a few of you out there experiencing similar stuff.


Last edited:
it could be like this

i experience the same thing when I am about to blackout.
When I am close to blackout, diaphragmatic cnotractions get so frequent and strong that the intraalveolar pressure is lower then intraparenchimal pressure of the lung, thereby recalling blood from the the interstitial capillaries into the alveoli.
When i dove with no limits ballast, I dove to 48 meters wihtout spitting any blood, but when I blacked out during a constant at 33m, I did spit blood. That is why I think that spitting blood does' nt depend on the depth - and, thus, on the blood recalled by the blood shift mechanis- but rather on the frequency and -most importantly- the INTENSITY ( in terms of the negative intraavlveolart pressure generated) of the diaphragmatic contractions.

hope this can help

Andrea, MS
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