Physiology

Oxygen Toxicity for Divers

Following training guidelines and conservatively planning our dives can reduce our risk somewhat, but learning how oxygen toxicity affects us and how we can prevent it can mean the difference between a fun dive and one that ends in injury. Push back against complacency and unquestioning acceptance of common practices—understand the effect of oxygen on your body before you plan your next dive.

Photo courtesy of DAN

Diving with a Defect - Understanding the PFO

Modern discussion has led to a wide variety of recommendations on the topic from a number of sources, leading to some confusion. While some agencies and physicians recommend diving conservatively with a known PFO, others recommend surgical closure, and still others advise that there may not be a benefit to closure and that divers should just be aware of their condition.

The so-called “dive response” is not merely a reflex in dolphins, but an active response.

Why aren’t dolphins getting bent?

Marine mammals are not above the physical principles and processes that lead to bubble formation in tissues following decompression. Scientists once thought that diving marine mammals were immune from decompression sickness, but beached whales have been found to have gas bubbles in their tissues—a sign of the bends. In any case, how some marine mammals and turtles can repeatedly dive as deep and as long as they do has perplexed scientists for a very long time.

Kiwi is good for yer

Can Antioxidants Protect Scuba Divers?

A recent study, published in The Journal of Physiology, shows that acute oral intake of antioxidants Vitamin C and E prior to a scuba dive can reduce alterations in cardiovascular function that are caused by a single air dive.

A group of professional divers were studied before and after a moderate scuba dive to a depth of 30 meters for 30 minutes, similar to those enjoyed by countless recreational divers.

Larger spleen enables Bajau to remain underwater longer

The Bajau are an indigenous people in parts of Indonesia renowned for their breath-holding ability when diving for food. They have been known to dive up to 70 metres using nothing more than a set of weights and a pair of wooden goggles.

Previously, scientists have speculated on whether dive capacity is related to spleen size, though no formal studies have been done on humans on a genetic level.

DDRC launches diving ear survey

Ear health problems are one of the most commonly reported issues by divers. Problems can range from a relatively simple condition, for example, “swimmers ear,” to a more serious condition such as barotrauma, which can result in lasting damage to the ear.

Currently, anonymous field data is sparse, therefore Devon-based DDRC is hoping to find out what type of ear problems are most frequently encountered whilst diving if any medical advice was obtained; and if not, what was the outcome.

Dr Neal W Pollock

A Quick And Dirty Review Of Gradient Factors

Renowned diving physiologist Dr Neal W Pollock filmed a EUROTEK TEKTalk where he discussed the foundations of decompression physiology, M Values and what Gradient Factors are.

Pollock is the Research Director at Divers Alert Network (DAN) and a Research Associate at the Center for Hyperbaric Medicine and Environmental Physiology, Duke University Medical Center. Both positions are based in Durham, North Carolina.

California Sea Lion (Zalophus californianus) seen in Santa Cruz, California

How seals avoid the bends

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.