DCS Risk Factors

Decompression sickness (DCS) is often covered in open-water courses but then mentioned only briefly in continuing education. While it’s true that our understanding of the condition has been mostly stagnant for the past two decades, that is beginning to change, and it’s time to start updating divers and students as researchers discover new information. 

Medical & Fitness
DAN

A recent big-data study performed by a DAN Europe research team used modern statistical analysis techniques to dig into a sample of nearly 40,000 open-circuit recreation dives and look for patterns and clues about DCS risk factors in real-world cases. Some of what they’ve found confirms our previous knowledge and opens entirely new avenues for research into the factors that contribute to DCS risk. Here’s what we’ve learned.

Divers Adrift – Surviving Being Lost at Sea

Exploration isn’t easy — if it were, everyone would do it. The reality is that the next big shipwreck to be found may be hundreds of miles from the nearest coast, tucked into a remote cove hours from civilization or in an area with huge tidal currents. 

Tech and Training
DAN

The more difficult a wreck is to get to, the more rewarding its discovery, but also the more likely it is that you’ll run into trouble during or after your dive. Challenges become hazards quickly, and many offshore adventures are rife with risk factors that make it more likely that you’ll surface from your dive without a boat in sight.

Whether your charter sprung a leak and became a new dive site or drifted off in search of another diver here’s what you need to know to survive.

Gas Management 101

It’s almost impossible to overstate the importance of gas management — unless you have gills, running out of air will get you in big trouble underwater. Planning your dive around gas consumption isn’t difficult and shouldn’t take long, but both new and experienced divers continue to put themselves in harm’s way by forgetting or forgoing this type of planning. 

Tech and Training
DAN

Checking your air a few times during a dive and coming up as the gauge nears zero is not dive planning. Before you hit the water this summer, brush up on the basics of gas management — this will help keep you safe and might even extend your bottom time.

Neurological DCS for Divers

Cases of decompression sickness (DCS) that involve neurological symptoms are fortunately rare, but advanced and mixed-gas divers in particular should be aware of the signs and symptoms and know how to respond if they or one of their buddies experiences a dive injury.

Medical & Fitness
DAN

Whether you have the skills and training to care for a diver yourself or you want to be prepared to help until a more experienced caregiver is available, learn the basics of assessing post-dive symptoms.

Articles like this one are no replacement for training, but they are a good way to refresh or build your awareness of the importance of emergency-response skills.

Avoiding Bad Gas – Tips for Preventing Breathing-Gas Contamination

Incidents involving bad breathing gas—air, nitrox, trimix or another mixture—are rare, yet they do occur. Health effects on divers vary depending on the contaminant breathed. Among the most severe symptoms of breathing contaminated gas are impaired judgment and loss of consciousness, both of which may be deadly underwater.

Tech and Training
DAN

Sources of contamination include hydrocarbons from compressor lubricants, carbon monoxide (CO) from engine exhaust (or overheated compressor oil) and impurities from the surrounding environment such as methane and carbon dioxide (CO2). Dust particles in breathing gas can also be hazardous, potentially impairing respiratory function or damaging diving equipment. Excessive moisture can cause corrosion in scuba cylinders and other dive gear and may cause regulators to freeze due to adiabatic cooling (heat loss following increased gas volume).

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Look After Your People

In the book Into Thin Air, journalist Jon Krakauer tells the story of five people who died near the summit of Mount Everest in 1996. Two were expedition leaders, one was a professional guide and two were their clients.

Words:
Simon Pridmore
Images:
Simon Pridmore
Download the full article as pdf ⬇︎
Op'eds and commentaries

The clients, like most people who sign up for Everest expeditions, were not mountaineers or hard-core climbers. They were folk with little advanced climbing experience, but plenty of money, plenty of guts and a dream. They died primarily because they placed their lives in the hands of professionals, who then failed to keep them safe. On that day, the professionals broke rules and departed from set procedures, which they themselves had established and which had previously contributed to their exceptional safety record.

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A Brick Can Do That!

On 11 May 1996, five people died near the summit of Mount Everest. Two were expedition leaders, one was a professional guide and two were their clients. The events were first recounted in the book Into Thin Air written by journalist Jon Krakauer, who was up there on the mountain that day.

Words:
Simon Pridmore
Images:
Download the full article as pdf ⬇︎
Op'eds and commentaries

The clients died mainly because the professionals persisted with attempting to reach the summit despite the fact that they had passed their turnaround time; that is, the point in the day at which an attempt on the summit would normally be aborted for safety reasons. The concept of establishing a turnaround time and sticking to it religiously had been a major factor contributing to the professionals’ hitherto exceptional safety record on Everest.

his Scuba Confidential column in issue #97 is adapted from a chapter in Simon’s book Scuba Exceptional: Become the Best Diver You Can Be. Simon Pridmore is the author of the international bestsellers Scuba Confidential: An Insider’s Guide to Becoming a Better Diver, Scuba Professional: Insights into Sport Diver Training & Operations and Scuba Fundamental: Start Diving the Right Way. He is also the co-author of the Diving & Snorkeling Guide to Bali and the Diving & Snorkeling Guide to Raja Ampat & Northeast Indonesia.

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The Lone Wolf

The scene for this story is a liveaboard in Southeast Asia, which, on most of its itineraries, would offer guests four dives a day and imposed a 60-minute maximum dive time for each dive. Divers were also asked to stay together on a dive, and follow their guide. There were 12 divers and three guides, so each guide would usually be leading four divers.

Words:
Simon Pridmore
Images:
Download the full article as pdf ⬇︎
Tech and Training

On this particular trip, one of the divers, Brian, made it very clear that he did not like these policies. He would often swim some distance away from the group, complaining afterwards that their bubbles kept getting in his photographs. Sometimes, he would swim in completely the opposite direction from the group, on the basis, as he would subsequently explain, that the guide had been taking them all the “wrong” way. And, on every dive, he would just refuse to come up at the 60-minute time limit. When he did eventually surface, he would boast about how much air he still had left.

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Risk and Uncertainty

Why numbers don’t mean much when it comes to your behaviours!

Gareth Lock writes the first of a series of articles, which are extracts from his recently published book <i>Under Pressure: Diving Deeper with Human Factors</i>. In this piece, he looks at risk management in diving and shows that most of the risks we manage are not actively managed at all. They are subject to emotions, biases and mental shortcuts, and we are actually managing uncertainty.

Words:
Gareth Lock
Images:
Download the full article as pdf ⬇︎
Tech and Training

I remember watching a presentation by Sami Paakaarinen on the recovery of two divers who were his friends who had died while diving in the Plura cave system in northern Norway in February 2014. He put up a slide that said, “We took a calculated risk. Unfortunately, we were not very good at maths.” He was referring to the dive where the two divers became trapped and panicked at a depth of more than 130m below the surface. They died and others on the dive were lucky to make it out alive.

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