Nitrox question

[pkpuffer]

Check with DAN and follow their advice.....seriously!

 

[BugHunterNY]

All things being equal, your question sounds like you're asking if there is a benefit of diving Nitrox over air for your condition; not "should I dive with Nitrox or not dive at all". If this is the question, I surmise that if you're going to dive, more oxygen in the mix would unquestionably be better than less... Provided you're not exceeding MOD or trying to give yourself ad hoc oxygen therapy, I can't imagine more oxygen in your breathing mix adversely affecting you.


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[PhatD1ver]

well, good points, some stuff to think about, and I'm not giving up diving for this nutty condition (which to respond to TS&M is just an abnormal number of PVCs and PACs each day - about 14,000)... the doc says that if we hadn't been monitoring it for four years, he'd never have signed off on my dive medical when went to Thailand to get my OW... but since there has been no change, and even my exercised induced 'episodes' have all been controlled easily, he feels like I'm good to go for normal rec diving parameters. (kind of like I can' get a CLASS II flight physical any more, so no being a commercial pilot.. but I can fly private and under instruments all day any day)..

Assuming I can't control my exercise stress under water assumes facts not evidence. I know my limitations, and I have a buddy that is also limited in experience, and tolerance for adventure. So, we will be selecting dive sites where the only current we want to deal with is for a drift dive, and depths that are commensurate with her comfort zone (above 30m for sure)...

 

[TSandM]

I'm with your doc! That's a LOT of irritability. I assume you have had an echocardiogram to rule out any kind of myocarditis or dilated cardiomyopathy?

 

[rongoodman]

If you had access to a dry suit, wearing a Holter while diving might provide some interesting data.

 

[PhatD1ver]

and the 'scientific' results of my experiments are thus...

Of 7 of 9 dives, I used EAN32 in depth profiles between 15.6 and 25.6 meters (average max depth was about 18.5m) overall average depth was 14.8meters.

I can say this, call it placebo effect if you want, but I know what it feels like to climb out of the water and into a banca after 4 dives on air in a day, and I know how I felt climbing out for two days.

Pretty good results from that perspective. Now to this arrythmia thing... I can say that the ONLY dive where my little arrythmia showed up was on our first shore dive (on AIR)... no biggie, but I know the feeling. On dive 6, we had a hard swim up current that in the past would have set me off... again, no noticeable issues, and that includes a couple unforeseen stressors.

So, overall, it's meaningless data to some people, for anyone over 50, I'd say do your own test. It was an extra $70 for me for those 7 dives, that I enjoyed much more.

---------- Post added September 10th, 2014 at 01:52 PM ----------

I have a dry suit, we just need to be sure the holter won't be damaged by dropping down to 25m with it on.

---------- Post added September 10th, 2014 at 01:56 PM ----------

I get a FULL workup on my heart every year including stress tests, EKC, ECG, and about 20 blood tests, not to mention the holter. They pull blood every 2 months when I get my meds for hypothyroidism, to test for any enzyme activity. I seriously am very cautious about it. Just not so cautious as to sit on the couch and never dive again.

 

[freewillie]

I've always found it interesting that people have been posting medical questions in a chat forum to lay people. It is very much like the blind leading the blind. With the exception of TSandM who is an actual medical doctor I would presume all of the other people who replied are not medically trained. I sort of understand the desire to run a medical scenario through a chat to see what other people's opinions are on the subject. But, it is very different when asking medical advice about what to do for feeling nauseated from seasickness to what do you think about my heart arrhythmia. Full disclosure in that I am an actual medical doctor who just happens to love diving.

First. Basic heart physiology. The heart is a structure of muscle, arteries and veins, and nerves. The nerves carry the electrical signals that enables the heart to beat in the nice rhythmic sequence we associate with normal heart beats. The muscles then contract in a specific sequence to produce that normal heart beat. And the arteries and veins carry the blood to and from the muscles. I usually describe the heart to my patients like a room. The wires in the room that turn on the lights are like the nerves that carry the signal. The muscles are the walls themselves. There are doors like the valves that regulate the blood in and out of the rooms. And the arteries are like the pipes that bring the water to the sink and the veins are the drainage pipes that carry the water away.

If you have an arrhythmia then it is a short circuit in the wiring. You may have normal pipes and plumbing but the rhythm is dictated by the electrical system. Generic "heart disease" doesn't specify any structure. It could be the electrical system, or the arteries, or event the valves or muscles themselves. Most of the time, but not always, it refers to arterial disease.

For the record an ECG/EKG simply detects 10 seconds of your heart beats. It is a basic indicator of whether you have normal rhythm only for those 10 seconds and if you have any heart damage to the muscles in the past. It offer NO information about the underlying health of your arteries. It may provide evidence of arterial disease ONLY when you have had a prior issue with artery related heart disease in past - namely you have a remote history of an actual heart attack. You can have over 90 blockage of your heart's arteries but without actual damage to heart muscle (the walls/dry wall of the room) you can still have a normal ECG. In the same manner you can have significant blockages to put you at risk for a heart attack but still have a normal stress test if those blockages fall below the level that a stress test can detect. Also, keep in mind that a standard exercise stress test is only able to detect significantly blocked arteries in UNDER 50% of patients with KNOWN coronary disease. That means that there is a significant false negative value associated with a stress test. In other words, you can have significant heart disease and still have a normal stress test. And the only thing a blood test can really tell is what your relative risk factor is for arterial heart disease based on how high or low your cholesterol levels are.

You have not specified although I suspect you have premature ventricular contractions from the post as your specific arrhythmia. Those are benign irregularities but is significantly different than more significant problems like atrial fibrillation. The former doesn't have a significant restriction to diving although low dose beta blockers might be used if the number of PCC/PAC's are significant. The latter depends on the cause and how well controlled the atrial fibrillation is with medication. Whether or not a person can dive with atrial fibrillation is situational and depends on the patient.

In addition there is no benefit to supplemental oxygen for increasing oxygen levels in your blood. Up to 99% of the oxygen in your blood is carried by a hemoglobin molecule in your red blood cell. That means less than or no more than 1% of oxygen is actually dissolved in the blood so the use of Nitrox for oxygenation purposes is not helpful. Remember it's use for diving is to help reduce the accumulation of nitrogen in the blood, not actually increase the amount of oxygen inhaled.

You might be getting the picture that the answer to your question is a little more complicated than can be answered in a chat room with most of your audience not trained as medical professionals and therefore unable to give medical advise. You may want to call DAN for a second opinion or discuss the issue with your doctor again.

 

[Polari]

In addition there is no benefit to supplemental oxygen for increasing oxygen levels in your blood. Up to 99% of the oxygen in your blood is carried by a hemoglobin molecule in your red blood cell. That means less than or no more than 1% of oxygen is actually dissolved in the blood so the use of Nitrox for oxygenation purposes is not helpful. Remember it's use for diving is to help reduce the accumulation of nitrogen in the blood, not actually increase the amount of oxygen inhaled.

Herny's law says :
"At a constant temperature, the amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid"

Based on that your statement is wrong and possibly dangerous.


Also on the book Deco for Divers page 103 it says:
As the haemoglobin is already 97% saturated with oxygen it only takes a slight increase in partial pressure of oxygen for the haemoglobin to become completely saturated.Once this happens it cannot bind with any more oxygen and any additional oxygen can only be carried dissolved in the plasma.As the partial pressure of oxygen is increased past this saturation point the amount of oxygen carried by the blood is determined by Hernys law.
This means that the amount of oxygen dissolved in the blood increases linearly as the partial pressure increases.

 

[freewillie]

Herny's law says :
"At a constant temperature, the amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid"

Based on that your statement is wrong and possibly dangerous.


Also on the book Deco for Divers page 103 it says:
As the haemoglobin is already 97% saturated with oxygen it only takes a slight increase in partial pressure of oxygen for the haemoglobin to become completely saturated.Once this happens it cannot bind with any more oxygen and any additional oxygen can only be carried dissolved in the plasma.As the partial pressure of oxygen is increased past this saturation point the amount of oxygen carried by the blood is determined by Hernys law.
This means that the amount of oxygen dissolved in the blood increases linearly as the partial pressure increases.

The statement is not wrong. It is basic physiology. Herny's law is correct and you will get more oxygen to dissolve but the real question to you is if you are already at 97% - 100% saturated with oxygen what is the effect of increasing oxygen capacity of the blood? In physiologic terms while exercising there is no additional benefit. We are talking about what effects of delivering oxygen to body tissues, not deco diving. This is diving at recreational limits and at recreational depths. Your ability to deliver oxygen to the tissues is dependent on vascular activity, i.e. how efficiently does your vasculature (arteries) deliver the saturated blood. Factors such as physical fitness and exercise capacity have far greater effects on tissue oxygen.

This is why I dislike having medical questions asked in a forum where the people answering don't fully understand the physiology and basic medicine. They tend to pull things out that are in the small context correct but do not necessarily apply to the big picture. Not to pick on you specifically. A good analogy is interpreting medical studies. The first question to ask is if your patient would have fit the inclusion criteria to be part of that study. These guidelines on how they chose their patients and what criteria where used to include and for that matter exclude candidates for the study. So for a study that focused on women and breast cancer you can't always extrapolate any findings of a breast cancer study with all women and assume the same holds true for men. It might, but you would have had to include a small number of men to know for sure that the study results apply to men. Likewise if all the study subjects were over 50 the study can't translate over to anyone who is 25 years of age. It might, but it might not as well.

And the worse types of associations are the personal experience ones that tend to pop up in chat rooms. Take two different people and assume both patients complain of chest pain. Person A goes to the doctor and gets diagnosed with chest pain. The doctor says that the patient has heartburn and gives them and antacid. At a party someone says to patient A that they have chest pain, to which they reply, "Oh, I had the same thing and my doctor told me it was heartburn. Take and antacid and you'll be better." Patient B has chest pain and goes to the doctor. Patient B gets diagnosed with heart disease and winds up with an angiogram and stent/or heart bypass surgery. Patient B is at a party when some tells them they have chest pain. Patient B then says, "You'd better go to your doctor immediately. I had the same thing and I wound up with bypass surgery. It could be your heart." I've seen this happen over and over. Your personal experiences then influence your advice based on what you have experienced. And while those experiences may be true they may not be applicable the question asked in a chat room.

I expect someone else will now try and point out some flaw in my responses and answers. I don't really want to keep arguing the point. But internet chat rooms are a very poor area to ask certain medical questions for medical advice. If there are any real medical questions you are better off asking your primary care doctor, or a specialist, or even calling DAN.

 

[Polari]

The statement is not wrong.

Yes it is.

the real question to you is if you are already at 97% - 100% saturated with oxygen what is the effect of increasing oxygen capacity of the blood? In physiologic terms while exercising there is no additional benefit.

While diving of course there are benefits because of our good friend Herny.If you don't know what are the benefits you surely need to read more on the subject.

This is why I dislike having medical questions asked in a forum where the people answering don't fully understand the physiology and basic medicine. They tend to pull things out that are in the small context correct but do not necessarily apply to the big picture.

This is not pulled out of the context.IT IS THE CONTEXT.

This is why i always go to 2 or 3 doctors.Because one doctor does not know everything and may know or may not know all the answers.