Research

Intrapulmonary Shunts: Another Cause for a Right-Left Shunt

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15 October 2018

Many of us are familiar with the concept of PFO’s and how they may be responsible for allowing bubbles to cross from the venous (pulmonary) to the arterial side. When this occurs, we are talking about a Right-Left Shunt, RLS and a potentially increased risk for developing Type II DCS. There are other sources that may lead to a RLS, …

A Letter of Caution from NEDU: Don’t Dive Cold When You Don’t Have to

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15 October 2018

Many of us may be familiar with the NEDU study:   Gerth WA, Ruterbusch VL, Long ET – The Influence of Thermal Exposure on Diver Susceptibility to Decompression Sickness Technical Report. Panama City (FL); Navy Experimental Diving Unit; 2007. Report No: 06-07 http://archive.rubicon-foundation.org/xmlui/bitstream/handle/123456789/5063/NEDU_2007_06.pdf   However, some divers have mistaken the data to mean that they should be cold to decrease …

How Much Is In Your Loop?

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15 October 2018

Although alluded to in your initial rebreather training, the idea of ‘optimal loop volume’ escapes some divers. Even among advanced rebreather divers, the loop appears to be managing them instead of them managing their loop. They learned to cope, instead of, to control it. What is ‘optimal loop volume’? The terms frequently used when explaining proper loop volumes are ‘optimal’ …

Myth Buster: Argon, the Superior Dry Suit Inflation Gas?

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Myth Buster Argon, the Superior Dry Suit Inflation
15 October 2018

Staying warm during the dive is not just a matter of comfort. As we have learned from the 2007 NEDU study, it also affects our decompression and, subsequently, our DCS risk. Supplemental insulation provided by dry and wet suits will shift the Lower Critical Temperature (which is the ambient temperature at which heat production responses are initiated) to lower values …

Petrel Tissues Demo

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Shearwater Research has a great video which not only highlights and demonstrates the Petrel’s Tissue Graph feature, but also gives a great visual demonstration of decompression loading and off-gassing. Absolutely worth 13 minutes of your time, even if you don’t dive a Shearwater Petrel.

How We Learn Best: Improve Your Dive Learning Experience

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9 March 2018

Ever wondered how we learn and how we retain what we learned? Have you noticed that you will retain less than 100% of the material presented? Furthermore, because you zone out, get distracted, or do not comprehend, you are not even cognizant of the things you see and hear during the class. Every time a new concept or task is …

Careful What You Eat: Gassy Divers More Prone to DCS?

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9 March 2017

Two articles were published last year describing how colonic fermentation promotes decompression sickness in ratsNote1 and humansNote2. The gas of concern is not methane but rather hydrogen. Both are being produced by bacteria that naturally reside in our colons. Hydrogen is an inert gas that is more soluble but less dense than helium (0.082 g/L vs. 0.178 g/L). It is …

Shaken, Not Stirred – Spending Time On A Vibrating Mattress Reduces Bubbles

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6 January 2017

During a lecture preparation, I came across an article from 2009 describing that spending time on a vibrating mattress, before the dive, reduces bubbles. This study remained one of a kind until this year when another study reported the effects of pre-dive vibration on bubble load. In all, I could only find two studies and an editorial comment on this …

Why You Want to Stay on Your Loop AFTER the Dive

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28 December 2016

I recently summarized a 2013 article about IPAVA (Intrapulmonary Arterio-Venous Anastomoses) shunting bubbles from the right side to the left thus risking type II DCS. Further review on this topic revealed more articles and discussions within the science community. My goal is to summarize and relate their findings for you. There is compelling evidence that EVERY diver is susceptible to …