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This is terrible news. Jared was the only person who rivalled his dad for the mantle of technical diving's quintessential gentleman. An absolutely 'top bloke' as we say in NZ, whose desire to serve the community seemed more important to him than his own business interests. Jared and Lamar have...

Hi Felix, I think it would be a little grandiose for me to claim that there is some sort of 'test program' planned. I suspect that this will progress in small incremental / anecdotal steps and it will never really be something validated by numbers / data other than accumulated experience. The...

Hello again Eric, The quote you cite from Tauchmedizin does not convince me that Buhlmann actually measured (as opposed to calculated) nitrogen washout (whereas Hlastala measured it), and nor does it convince me (or even imply) that he correlated his calculated changes in nitrogen washout...

Hello, This subject has come up in a few threads elsewhere, but the 'official' (peer reviewed) report on the hydrogen dive performed by Richard Harris in the Pearse Resurgence last year was published yesterday in Diving and Hyperbaric Medicine Journal. I have attached the paper here. Harris...

Hello, This post raises a number of questions. It implies (though you don't state it definitively) that some of the computers you tested did "take account of aggravating factors". I would be curious to know what factors were taken into account by those computers? There are many reasons why...

Hello Crofrog, These are all very good questions. In relation to 'always grade 4 bubblers', we have known for some time that there some divers who consistently bubble a lot and some who don't. The short answer is that we don't know why this is. There are some hypotheses, but none proven...

Hello Mr V, Unfortunately this is not true. You are assuming that the only cause of CO2 problems is scrubber failure or bypass leading to CO2 inhalation. That is one way in which hypercapnia can occur, but its certainly not the only or even the most important one. It is also possible to become...

Hello, Great thread. After the publication of a landmark study (arguably the most important in the last 20 years) by David Doolette and Greg Murphy less than 3 months ago, events like this should no longer surprise us, and we should definitely stop referring to 'deserved' vs 'undeserved' DCS...

Hi Eric, At least some degree of caution is warranted, especially if you are dealing with a steel cylinder. I had previously heard stories of this nature and always wondered if they were apocryphal, but then this (see below) got submitted, and we published it just a three months ago...

Hello Joebob, Yes, that's exactly what it means. Indeed, it has been done with animals breathing oxygen at 3 ATA. You can see a description of this famous old experiment here. Hello Smache, Yes, pretty much. Basically, the partial pressure of oxygen in a tissue never rises enough for oxygen...

Hello, Lots of good comments in this thread, but this question comes closest to pointing at the complete answer to the OP's question. It is actually quite a tricky one to get one's head around, but if you're interested, here it is. To understand it, you need to understand some fundamental...

Hello, A great question by the OP, though the prediction calculations are slightly off. We don't have 21% oxygen in our lung alveoli during normal breathing; it is about 13%. That's because there are gases other than nitrogen and oxygen present (including CO2 and water vapor). A bit of...

Hello, If changing sorb between two dives on the same day the key elements are to: Make sure you actually change the sorb Make sure you install the canister (forgetting it entirely it has happened at least twice that I know of) Make sure you install the canister correctly (e.g. O ring and...

Hello, Diving and Hyperbaric Medicine Journal published a series of 20 divers who underwent this procedure because of ear equalizing problems. 15 improved with 10 completely cured of problems. The paper is available on pubmed central and can be downloaded for free here. As far as I am aware...

Hello, Diaphragmatic movement is not the only avenue for lung expansion. Upward and outward movement of the chest wall would also accommodate lung expansion. With that said, all involved structures (chest wall and diaphragm) incorporate skeletal muscle which would have to not be actively...

Hello, Gelirfella, while it is true that the exact mechanism by which alveolar gas enters the pulmonary circulation during pulmonary barotrauma is not well defined, there is overwhelming (essentially incontrovertible) evidence that it occurs. Specifically, in arterial gas embolism occurring in...

Hello, There certainly is one way: if there is severe hypoxia oxygen certainly becomes the "dominant factor in the respiratory drive" - at least in some subjects. We are currently demonstrating this in a series of experiments in which we make subjects hypoxic, but we are not the first to have...

Hello, In fact, it does. Several other commentators on this thread have correctly pointed out that the most important influence on the drive to breathe is generated by carbon dioxide levels in the arterial blood - higher CO2 = greater drive to breathe. However, if you have a higher arterial...

Hello, Just to put some perspective on this, the only published randomized double-blind trial of any intervention in decompression sickness (DCS) was an NSAID (as an adjunct to recompression). I have attached the paper. We showed that divers who received the NSAID had equivalent final outcomes...

Hello, Yes, we came out of the Pearse on Thursday, and yes, Harry and Craig completed a 13.5-hour dive to 230m during which hydrogen was introduced below 200m as diluent in a meg rebreather. The goal is not so much to eliminate helium, but rather to eliminate the small amount of dense nitrogen...