Controlled Emergency Swimming Ascents (CESA) are a fundamental component of diver training, simulating ascent without a gas supply. Now, a new study led by Olivier Castagna and colleagues at the French Military Diving School has raised questions about whether this vital drill might be more taxing on the lungs than previously assumed.
The technique presumably works because it helps control gravity sensors in the abdomen--a lesser-known input to our fine-tuned balance system.
The brain is traditionally thought to sense body position in three ways. The inner ears sense motions of the head; the eyes see where the head is; and tiny sensory organs in muscles and tendons sense where the rest of the body is.
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.
Thermal issues affect the comfort, performance and decompression stress experienced by divers. The impact varies with the timing, direction and magnitude of the thermal stress. Thermal protection can be provided by a variety of passive and active systems. Active systems should be used with particular care since they can markedly alter inert gas exchange and decompression risk.
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.
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.
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.
Asthma is a respiratory condition that affects 3-8% of the general population, thus also divers or would-be divers. It is defined as an increased responsiveness to the lower airways to multiple stimuli.
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.
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.
