Decompression illness

IPE is the abnormal leakage of fluid from the bloodstream into the alveoli, the microscopic air sacs in the lungs. Symptoms include shortness of breath, coughing up bloody sputum, and respiratory distress. Leakage into the alveoli results in fluid buildup in the lungs, and interrupts gas exchange, similar to drowning. It is important to note that fluid resulting from IPE comes from within the body, rather than from inhalation of surrounding water.

When air-breathing mammals dive, their lungs compress. The ultra-deep-diving feats of some marine mammals go beyond our current understanding of respiratory physiology and lung mechanics. But historically, researchers assumed the chest structure of marine mammals meant their lungs compressed automatically at great depths, an adaptation that prevented them from taking up excess nitrogen and getting the bends.

According to CAS’s Matt Wandell the chamber is fairly simple in design and can bring a fish up to to surface pressure in around 20 hours or so without adverse effects.

Aside from burst swim bladders, fish, like humans, can also get decompression sickness when exposed to rapid changes in pressure during capture.

“Bent” fish are most likely widespread in the live reef fish trade, as most of the species that have been examined were found to suffer symptoms of decompression sickness after capture from shallow depths of 10 to 15 metres.

Documentation of lung collapse and estimation of the depth at which collapse occurs has been difficult and only obtained in a few species.

Researchers led by Birgitte McDonald at the Scripps Institution of Oceanography netted a female adult California sea lion (Zalophus californianus), anaesthetised the animal and fitted it with loggers to record oxygen pressure in its main artery and the time and depths to which it dived.

A research team at the Duke University Hyperbaric Centre, (North Carolina, USA) has won a Johnson Space Center (JSC) Group Achievement Award from NASA. The Durham-based team comprising Dr Neal W Pollock, Dr Richard Vann, Mike Natoli and Dr Richard Moon developed an in-suit light exercise pre-breathe regimen to prevent decompression sickness from developing in astronauts.