Weekly Tec News

Gear

Aqua Lung/Apeks now offer an O2 clean SPG.

Many of you probably already know this, but Dive Rite now offers a BC Hose Quick Disconnect Adapter for connecting the short inflator hose common to many side mount 1st stage regulators to a second hose allowing it to connect to the inflator with less strain on the inflator, the hose or the connection between the two. I had a chance to try it this weekend, and was please. Of course, with this longer hose set up, some consideration must be given as to how you plan to route the hose. Here, Dive Rite provides their suggestion.

Training

PADI’s Sidemount student manual is finally available. It is not yet on the website, so contact your sales rep. Just a reminder, this manual covers both recreational and technical side mount in one book; no need to buy two books if you are planning on doing both. Needless to say, I am looking forward to getting mine.

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Research

Last week I focused on Oxygen Toxicity, so this week I am trying to cover a broader range of topics.

This one is not particularly new, but it ties in with my recent blog on risk. Researchers analyzed rebreather fatalities between 1998 and 2010 and found that “No particular brand or type of rebreather was over-represented. Closed-circuit rebreathers have a 25-fold increased risk of component failure compared to a manifolded twin-cylinder open-circuit system. This risk can be offset by carrying a redundant ‘bailout’ system. Two-thirds of fatal dives were associated with a high-risk dive or high-risk behavior” and concluded that “While rebreathers have an intrinsically higher risk of mechanical failure as a result of their complexity, this can be offset by good design incorporating redundancy and by carrying adequate ‘bailout’ or alternative gas sources for decompression in the event of a failure. Designs that minimize the chances of HMI errors and training that highlights this area may help to minimize fatalities.”

This paper looked at freshwater divers diving at altitude (294 m) with trimix to 45 m depth, and they were looking at changes in cardiovascular function. They observed a decrease in diastolic blood pressure and decreases in the volume of blood being pumped by the left ventricle (the left ventricle pumps oxygenated blood throughout the body) per beat, with a corresponding increase in heart rate. These changes could be observed up to 24 hrs later. This data suggests that deep dives at altitude may be stressful to the heart.

Media

There were a couple of posts on the PADI TecRec Blog this week. In the first, some suggestions for teaching technical diving is presented. I have already started using one of them. In the second, a Rebreather Instructor Trainer talks about how making the jump to rebreathers changed his business.

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