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To simulate pressure effects and experience thoracic compression while breath-hold diving in a relatively safe environment, competitive breath-hold divers exhale to residual volume before diving in a swimming pool, thus compressing the chest even at depth of only 3–6 m. The study was undertaken to investigate whether such diving could cause pulmonary edema and hemoptysis. Eleven volunteer breath-hold divers who regularly dive on full exhalation performed repeated dives to 6 m during a 20-min period. The subjects were studied with dynamic spirometry, video-fibernasolaryngoscopy, and single-breath diffusion capacity of carbon monoxide (DlCO). The duration of dives with empty lungs ranged from 30 to 120 s. Postdiving forced vital capacity (FVC) was reduced from mean (SD) 6.57 ± 0.88 to 6.23 ± 1.02 liters (P 0.05), and forced expiratory volume during the first second (FEV1.0) was reduced from 5.09 ± 0.64 to 4.59 ± 0.72 liters (P 0.001) (n = 11). FEV1.0/FVC was 0.78 ±…

INTRODUCTION: Breath-hold diving has been practised since the dawn of humanity but is open to many risks. The consequences mainly involve the respiratory system. The pathophysiological mechanisms are complex because of the multiple forces applied to the body during breath-hold diving. OBSERVATION: The case reported here describes the development of haemoptysis during a single breath-hold dive to a depth of 26 m, associated with acute alveolar haemorrhage. Recovery was spontaneous. CONCLUSION: This event is rarely described and, although often associated with the more frequently reported pulmonary oedema of immersion, the mechanisms remain uncertain, but definitely multifactorial (barotrauma, thoracic blood transfer) and probably enhanced by deconditioning. All this emphasizes the extraordinary stresses that the alveolo-capillary membrane is subject to under these circumstances.
PMID: 18176390 [PubMed - indexed for MEDLINE]

When you start freediving equalization usually sets the depth limit. After some training it is oxygen consumption. Then again equalization and after learning frenzel it will be lack of oxygen again. This has been the main obstacles for depth hungry freedivers to overcome - but there is a third problem.

Hodně freediverů si myslí, že hlavním nebezpečím při freedivingu je samba nebo blackout. Samba bývá leckomu pro smích a pokud se při blackoutu neumře, je to také vlastně jen komická historka při posezení s přáteli-freedivery. Málokdo ale ví, že je tu ještě další riziko. V angličtině nazývané „lung squeeze“, v češtině prozatím bez názvu. Dokud se neujme jiné pojmenování, můžeme používat označení pneumo-tracheální poranění (PTP).

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Description from chestjournal.org

Pulmonary barotrauma of descent (lung squeeze) has been described in breath-hold divers when the lung volume becomes smaller than the residual volume (RV), with the effect of increased ambient pressure. However, the ratio between the total lung capacity and the RV is not the only factor that plays a role in the lung squeeze. Blood shift into the thorax is another important factor. We report three cases of hemoptysis in breath-hold divers who dove for spear fishing in shallower depths than usual. All of the divers performed voluntary diaphragmatic contractions at the beginning of their ascent, while their mouths and noses were closed. We suggest that the negative intrathoracic pressure due to the forced attempt to breathe in with voluntary diaphragmatic contractions contributes to alveolar hemorrhage, since it may damage the pulmonary capillaries.

Don't Get Squeezed!

Every year I before competition time I hear of people getting lung squeeze during their constant weight training. And every year I try to warn people to be safe and conservative when it comes to their lungs. A very few people take my general advice, but most do not assume responsibility for their own safety.

This year is no different.

I have tried to warn new freedivers that lung barotrauma is dangerous. Back in 2002 I experienced a horrible lung squeeze that convinced me that I would never dive deep again if I could not figure out how to avoid lung injury. I couldn't breathe properly for a month following my squeeze. But now I see that many freedivers who have been diving and competing for several years now have not understood the danger.

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