Lung water accumulation at breath-hold diving

My take on the article.

The article compared the result from different exercises. This is a good thing, because we actually don't really know what the cause is of ULC's. ULC's have been found in:
- Patients with heart failure suggestive for congestion of the lungcapilary's.
- Over-hydrated dialysis patients.
- Healthy mountain climbers, where hypoxia was suggested as the cause.

To my knowledge, there haven't been any tests yet in competitive cyclist or runners, which might also be relevant to rule out other causes of ULC's. Perhaps maximum performance might in itself cause ULC's, so further research is warranted to understand the meaning of this phenomena within healthy individuals.

ULC's are only what they are. An suggestion of fluid in the alveoli or the interstitium of the lungs. The cause is yet to be determined, and could be a combination of several factors. It could be pathological, physiological or both, and its relevance is difficult to interpreted with the current presented data.

While the article did a good job in comparing different dive situations, they didn't do a good job in providing information about their subjects. They didn't disclose information on the personal best of the athlete's and their accomplished results during the research. Neither did the authors disclose general information about the athlete's (age, lung volume) so that it is difficult to compare the results with other freedivers. Other researchers like those from Croatia, France and Australia do disclose this relevant information.

Overall, this is an interesting and meaningful article, but more information is required to be able determine its importance for freedivers and freediving safety in general.

Talking with Dr. D. Cialoni (one of the co-authors, member of the Apnea Academy Research team), he pointed me on 3 further publications which you may also find interesting, so I am sharing them with you:

1. Ultrasound lung comets: a clinically useful sign of extravascular lung water (Ultrasound lung comets: a clinically useful sign o... [J Am Soc Echocardiogr. 2006] - PubMed result)
2. Clinical and echocardiographic determinants of ultrasound lung comets (Clinical and echocardiographic determinants of ultrasound lung comets ? Eur J Echocardiogr)
3. Chest sonography detects lung water accumulation in healthy elite apnea divers (Chest sonography detects lung water accumulation i... [J Am Soc Echocardiogr. 2008] - PubMed result)

Regards,

Francesco

First Post

This is the closest thread I can find already started haha

I'm a rec freediver and writing my undergrad thesis on the MDR and it's evolutionary origin, however being a freediver I "knew" a lot of the response before I've started research. (or at least I would like to think that)

I'm looking for any published study on the idea that due to peripheral vasoconstriction / blood shift, blood plasma partially fill alveoli which helps prevent alveoli collapse. I read this all the time on forums but have been able to find no primary research or published study that suggests this.

Obviously this is what pulmonary edema is, but are there studies that suggest such fluids may actually facilitate deeper dives?

Does anyone know of a study which supports this idea?

Sethlake said:

I'm looking for any published study on the idea that due to peripheral vasoconstriction / blood shift, blood plasma partially fill alveoli which helps prevent alveoli collapse. I read this all the time on forums but have been able to find no primary research or published study that suggests this.

Obviously this is what pulmonary edema is, but are there studies that suggest such fluids may actually facilitate deeper dives?

Click to expand...

You have some details mixed up.

Descending into the depths leads to an expansion of blood vessels and the heart ("blood shift"), at first without any fluid leaving the blood vessels (thus no edema). So there is no direct connection between blood shift and pulmonary edema. Edema means that fluid has been "forced" (through different mechanisms) out of the blood into the tissue. You can have blood shift without edema. In fact, everytime you enter the water (even without diving below the surface) there is a blood shift. This is a consequence of our upright posture. When standing or sitting, a large volume of blood is pooled in peripheral veins (for instance in the legs). When you enter the water, this blood is redistributed towards the thorax.

When the blood vessels in the thorax and the heart is holding more blood than usual, you can reduce the volume of air in the lungs to a greater extent without risking any barotrauma of descent. The thoracic volume normally "occupied" by air, has now been replaced by blood from peripheral parts of the body (limbs, etc.). So in this respect, blood shift protects you from pulmonary barotrauma of descent.

To continue, and somewhat simplified, if you descend even deeper, there is a risk that the blood vessels are either overfilled or exposed to a too large pressure gradient, and this potentially leads to fluid leaving the blood vessels, going to the lung tissue or into the alveoli (this is pulmonary edema). There may be damage to the blood vessels in the lungs as well, leading to alveolar hemorrhage (bleeding). Both pulmonary edema and alveolar hemorrhage should be considered pathological consequences, as Trux wrote.

Here are some papers discussing the phenomenom commonly called "blood shift" (there are others besides these):
Hemodynamic changes in man during immersion with t... [Aerosp Med. 1972] - PubMed result
Depth limits of breath hold diving (an example of ... [Respir Physiol. 1968] - PubMed result
Pulmonary and circulatory adjustments determining ... [Science. 1968] - PubMed result
Simulated breath-hold diving to 20 meters: cardiac... [J Appl Physiol. 1987] - PubMed result
Physiological and clinical aspects of apnea diving. [Clin Chest Med. 2005] - PubMed result

/Johan

Thanks for the clarification!

I'll be spending some time with those papers!

Seth