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What do you feel the moment you exceed Residual Volume in a deep dive? What after the dive?

xristos

Well-Known Member
Sep 5, 2013
102
29
68
Greece
Residual Volume is exceeded on full inhale dives at ~30 meters 100ft give or take and could change through years of diving.

Personally I have dives when I won't feel anything particularly uncomfortable and times when it feels like if I proceed deeper I will get crushed by pressure bearing on the thorax. I have at times pushed this barrier and did blissful dives. Sometimes I get pressure contractions that feel scary(especially if I forgot to charge a mouthfill earlier).

After the dives I feel either fine or tightness in breath and inability to breath deep. Doing so anyways is painful and makes me cough. Diving further that day is knocking on the door of danger since even 5m hurt. Swimming back to shore is hard because of these circumstances.

Now once 24h have passed the acute symptoms subside and I feel almost normal although not quite.

I do this post as answer to Vincent because I think my answer to his question in this post https://forums.deeperblue.com/threa...-during-training-sessions.116779/#post-991633 is not decent and to add more information on the topic sharing this article:

https://err.ersjournals.com/content/25/142/506

Upon reading a sentence got my attention, "Respiratory symptoms have been reported in almost 25% of breath-hold divers after repetitive diving sessions."
So this means diving 2-3 or more days in a row? Is this statistic representative of the forum divers?

Also in the article:
"As mentioned earlier, during field diving a redistribution of blood occurs from the periphery towards the intrathoracic vascular compartment. This effect is present during mere head-out immersion, but becomes more pronounced during deep diving. At great depths transthoracic pressure becomes progressively negative, drawing the blood from the periphery into the thorax, on occasion resulting in a blood shift up to 1500 mL [52]. Pulmonary capillaries protrude into the alveolar spaces, replacing air, thus resulting in a decrease of RV and extension of the depth limit. However, this feature further enhances the risk of alveolar haemorrhage by causing the pulmonary capillary pressure to rise [12]."

So exhaling before resurfacing will save us from injury or is the blood drawn in the lung on the descent getting out of it as we ascend?
I believed that exhaling before surfacing was essential only when packing and that speed of ascent and descent didn't really matter but the article makes me think otherwise. What is your opinion/experience?

I prompt you to read the whole article.
 
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xristos

xristos

Well-Known Member
Sep 5, 2013
102
29
68
Greece
So does ascent - descent rate play part in lung injuries, in practice. Eg in normal ranges 0.6-1.3 m/s full lung dives will there be a difference?

Reviewing information on Google it seems that descent and ascent speed play a role in lung squeeze.
Aida instructor on the other hand suggested these are examples of internet misinformation(people who confuse scuba with freediving) and is dangerous.
 
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