Doppler grades

[BigJetDriver]

The Edmonds, Lowry & Pennefather tome is also very nice. Not cheap either, but also very good and with a slightly different emphasis IMHO.

Do you need works of reference? Well, it helps you sort out e.g. the good points from the less-well-thought-out responses in cyberspace or in some dive courses.

Dr Powell - our very own Dr Deco - has published many peer-reviewed papers (just like his colleagues all over the world) and many of these are referenced in the above-mentioned works of reference. I'm not aware that he's edited or written any specific work of reference himself aimed at the recreational or technical diver, although I hope he finds the time to do so at some point, as he has the great gift of combining easy-to-understand language with highly up-to-date knowledge and some very unique and valuable decompression notions.

As Fin's Wake has pointed out, a text like "Diving and Sub-aquatic Medicine" by Edmonds, Lowry and Pennefather, available from Best Publishing, can be one of the best choices for extending your knowledge about diving physiology. Yes, it is somewhat expensive. Yes, it is worth every penny!

As for our very own Doc Deco, I think it is more than high time that he came out with: "The Collected Works of...."!

Cheers, lads! :anakinpod

 

[Dr Deco]

Hello Scuba Board Readers:

Learning Doppler Bubble Dectection

There are not any courses being offered on this topic of which I am aware. A few years ago, there was one class at the University of Texas Health Sciences Center here in Houston. That was a one-time class and nothing has been held since.

The problem with Doppler is that it is necessary to have the correct blood flow sound from the heart [pulmonary artery]. This is not as easy as it sounds, and most do not do it correct initially. I know, because I did not.

There is a book chapter listed in the References below. It is the one that I wrote a couple of decades ago. All of the newer editions of Bennett and Elliott have other versions of this topic.

Dr Deco :doctor:

References
MR Powell, MP Spencer, and O von Ramm. Ultrasonic Surveillance of Decompression. In: The Physiology and Medicine of Diving, 3rd Edition, [P. Bennett, D. Elliott, eds.] pp. 404-434, Baillière Tindall, London (1982).

 

[Kendall Raine]

Saturation;

Sorry for slow response.

The dive was not 300+. Any ambiguity on depth is intentional, not your fault. The dive in the LA Times article was, however, deeper than 260. We only noted subclavian scores as I continue to lack confidence in my ability to grade precordial bubbles. I took a reading on myself at the precordium, but would have rated my score substantially less than the initial sholder readings.

We recorded Grade III to Grade III+ (K-M scale) subclavian bubbles 30 minutes post dive in each sholder. 60 minutes post dive John's scores had dropped to Grade II- and Grade I in his sholders. Mine had dropped to Grade III- and Grade I. I can't explain why one of my sholders didn't clear up better. I didn't take another reading, but would have been curious to see results 90 minutes out. Neither of us had any symptoms post dive. No fatigue, niggles, nothing. I have found after deep trimix dives that I very rarely have any fatigue, regardless of what the Doppler is telling me. I have found a strong correlation between exertion, primarily swimming, and scores. Also, sleep the night before shows a strong inverse correlation to scores.

Gasses used were 15/55 backgas with 50/25 and 100%.

Hello Kendall and Dr. Deco:

I just read a post about Kendall's recent dive to 300+ that was used as backdrop for an article about technical diving ... its on SB.

Kendall, if you're at liberty to say, how soon do you notice your precordium bubbles resolve one you start your surface 02? Do you listen and hear a gradual reduction in 'grade'?

Are you at liberty to discuss what schedules you use to 300'?

 

[Dr Deco]

Hello Scuba Board Readers:

Doppler Monitoring

Those are interesting results from your dive. I have not done much in the way of subclavian monitoring, but these bubbles are certainly easier to hear than those of the precordial region.

For the past three decades, researchers have tried to make correlations with Doppler bubbles and the outcome of a dive. It is difficult.

The statement that bubbles appear in greater abundance following exercise is a finding of several research groups in the past decade. It has also been found in animals over 30 years ago.

Doppler Bubbles and Sleep

Your observation that there appear to be more Doppler bubbles in a diver who has less sleep than one who is rested has not been noted before, to my knowledge. In laboratory studies, the subjects are always counseled to get a good night’s rest, and thus this topic does not arise. Your finding from the field is very interesting. Many thanks for that info.

Dr Deco :doctor:

 

[Kendall Raine]

The problem with observations like mine is they don't lend to step wise regression. That is, a poor night's sleep could combine with other factors like stress, work load, cold, etc. to foul up results. For that matter, being keyed up before a big dive often results in a poor night's sleep. So which came first, the stress or the lack of sleep? Attempts to quantify and measure factors like that just make engineers cranky.

Suffice it to say that if I'm going into a big dive feeling fatigued, I'll pad the deco. If a dive hasn't gone according to plan and I'm feeling off (emotionally) because of it during the hang, I'll pad the deco.

Hello Scuba Board Readers:

Doppler Monitoring

Those are interesting results from your dive. I have not done much in the way of subclavian monitoring, but these bubbles are certainly easier to hear than those of the precordial region.

For the past three decades, researchers have tried to make correlations with Doppler bubbles and the outcome of a dive. It is difficult.

The statement that bubbles appear in greater abundance following exercise is a finding of several research groups in the past decade. It has also been found in animals over 30 years ago.

Doppler Bubbles and Sleep

Your observation that there appear to be more Doppler bubbles in a diver who has less sleep than one who is rested has not been noted before, to my knowledge. In laboratory studies, the subjects are always counseled to get a good night’s rest, and thus this topic does not arise. Your finding from the field is very interesting. Many thanks for that info.

Dr Deco :doctor:

 

[Saturation]

Saturation;

Sorry for slow response.

I can't explain why one of my sholders didn't clear up better. I didn't take another reading, but would have been curious to see results 90 minutes out. Neither of us had any symptoms post dive. No fatigue, niggles, nothing. I have found after deep trimix dives that I very rarely have any fatigue, regardless of what the Doppler is telling me. I have found a strong correlation between exertion, primarily swimming, and scores. Also, sleep the night before shows a strong inverse correlation to scores.

Gasses used were 15/55 backgas with 50/25 and 100%.

Hi Kendall, no problem at all. Is your shoulder on the arm you used for monitoring doppler bubbles? Any old injuries on that shoulder?

Yes, the exertion and bubbling is a big issue I preceive, and one of Dr. Deco's hypothesis as a key player for bubbles. I surmise good rest means more efficiency and less movement on a dive the next day.

Has the 25% helium instead of 50% nitrox made a difference in your deco?

As for your schedule, is that relatively VPM-B or extensively padded?

 

[Saturation]

The problem with observations like mine is they don't lend to step wise regression. That is, a poor night's sleep could combine with other factors like stress, work load, cold, etc. to foul up results. For that matter, being keyed up before a big dive often results in a poor night's sleep. So which came first, the stress or the lack of sleep? Attempts to quantify and measure factors like that just make engineers cranky.

Suffice it to say that if I'm going into a big dive feeling fatigued, I'll pad the deco. If a dive hasn't gone according to plan and I'm feeling off (emotionally) because of it during the hang, I'll pad the deco.

Hi Kendall,

You can scale your feelings, its done frequently in psychological testing, so you can convert a qualitative variable like fatigue, into something with degrees of fatigue: scale of 1-10, 1-5. 1-3 etc,. Once you create your own, if you are internally consistent with selecting the choices in the scale it be used for you and later your buddies as at least its relatively accurate for the observer. Generally, the more numbers, the less consistent the scale becomes, so most end up with 5.

For example: 1= none at all, 2= I have no trouble lifting my tanks, 3= I strain to lift my tanks 4= I can't get off the boat without help, 5= I can't get back on the boat without degearing or help etc.,

Lots of testing are used for widespread usability [ a full PhD thesis, in fact] such as this cancer fatigue scale:

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9599354&dopt=Abstract

 

[Kendall Raine]

Yes, the left shoulder is an old injury site (hyperextension during a skydiving collision) and generally exhibits higher bubble grades. I have generally not done Doppler readings in series to measure grade decay over time, but now I'm curious about this.

I appreciate the thought about scaling factors. If I'm going to take the time to do one (e.g. fatigue) I might as well include others like exertion, stress, thermal issues as well as external factors such as visibility, current, etc. I'm going to modify my process to reflect qualitative dive data.

I have just started using 50/25 and all my data is based on 50/50 so I can't say whether there is a bubble grade correlation or a time to clear correlation. The deco reflects 50/25 and is a slightly modified RGBM shape. This is still an experiment for me.

I think

Hi Kendall,

You can scale your feelings, its done frequently in psychological testing, so you can convert a qualitative variable like fatigue, into something with degrees of fatigue: scale of 1-10, 1-5. 1-3 etc,. Once you create your own, if you are internally consistent with selecting the choices in the scale it be used for you and later your buddies as at least its relatively accurate for the observer. Generally, the more numbers, the less consistent the scale becomes, so most end up with 5.

For example: 1= none at all, 2= I have no trouble lifting my tanks, 3= I strain to lift my tanks 4= I can't get off the boat without help, 5= I can't get back on the boat without degearing or help etc.,

Lots of testing are used for widespread usability [ a full PhD thesis, in fact] such as this cancer fatigue scale:

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9599354&dopt=Abstract

 

[Saturation]

Yes, the left shoulder is an old injury site (hyperextension during a skydiving collision) and generally exhibits higher bubble grades. I have generally not done Doppler readings in series to measure grade decay over time, but now I'm curious about this.

I appreciate the thought about scaling factors. If I'm going to take the time to do one (e.g. fatigue) I might as well include others like exertion, stress, thermal issues as well as external factors such as visibility, current, etc. I'm going to modify my process to reflect qualitative dive data.

I have just started using 50/25 and all my data is based on 50/50 so I can't say whether there is a bubble grade correlation or a time to clear correlation. The deco reflects 50/25 and is a slightly modified RGBM shape. This is still an experiment for me.

I think

Sorry for late reply, I didn't see this in my in-box for stuff to answer.

I hear this a bit, sites of significant injury often seem to offgassing less than healthier tissue. Last thanksgiving, I dove with a seasoned cave diver through the Ginnie system for 2 days with 1.5 hour dives each day [max depth 100'] and he emailed me that Monday that he got mild DCI 1 the day I left; it happened on a shoulder with a previous injury albeit he was doing literally half the deco I was doing, timewise.

A quantification of those qualitative factors may help in making any regression analysis you intend. It may not need more work for external statistical validity, but it most likely will be internally consistent for your purposes. With instant-stat software available everywhere, it may point out some factors worth studying in more detail for higher statistical validity. Also, its a better way to, and a practical reason for, keeping a dive log.

 

[J1M1]

Gentlemen, if helium is such a great inert gas for scuba, then why do we all not simply always dive HeliOx?

I have never heard of HPNS occurring at tec rec depths, so that should not be the reason why.

IANTD now teaches a recreational trimix course designed to lower the narcosis depth . Others are teaching the same thing