After dive oxygen: shouldnt the diver decide?
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freewillie
Contributor
Anecdotal experience does count??? Just my case alone. I have done thousands of dives and I do one and only one dive where I come up with total numbness on one side and it is totally resolved by oxygen in 15 minutes ,,, and it is not reasonable to conclude that it was the bends and that oxygen and time resolved it? The oxygen and the diving "didn't count" because a doctor didn't make a definitive diagnosis?
Just a quick lesson in medical diagnosis. There are two types of figuring out what a patient has for a diagnosis. You can "rule in" where you present and based on history, exam, labs, and imaging you have a single diagnosis. Or, you can "rule out" for a disease where you have something and based on a screening test you either might have one of a number of things or completely don't have the condition.
Let's go back to my chest pain analogy. If you come to the ER with chest pain I'm going to do an EKG. Let's just say by history what you describe is classic angina. Chest pressure worse with exertion and relived by rest. To further suggest cardiac cause you received nitroglycerin and then pain got better. But your EKG is normal. Does that mean you don't have a narrowed artery in the heart causing your symptoms?
Given this scenario based on the EKG you haven ruled out for an acute heart attack. So you are not having actual cell death of the heart muscle. But there is stil a significant probability you still have heart disease in the form of a narrowed or stenotic artery. At this point you have ruled OUT for heart attack but have yet to rule IN for atherosclerotic heart disease.
So so we do the next step. The cardiologist does a stress test that is now positive for a blocked artery. You have now ruled IN for atherosclerotic heart disease. You now go to the cath lab and low and behold you have a 90% lesion and you get a stent.
But doctor, my EKG was normal. So how can I have heart disease. It's semantics. A myocardial infarction is a type of heart disease. But so is atherosclerotic heart disease. They have different definitions and different criteria for diagnosis and separate clinical criteria and treatments for both types of "heart disease". Not the same.
Let's take a diver who surfaced with some tingling in the arm. By definition it is either emergent DCI since the diver exited the water with symptoms. Or it is urgent since by definition numbness or paresthesia is neurologic DCI until proven otherwise. Now definitive therapy is Navy dive table 6 protocol until symptoms disappear. But the diver gets better with oxygen. At this point the diver has not yet ruled in, ie definitely has DCi. But getting better doesn't rule out DCI either. Quite the contrary. It has now increased the probability the diver has DCI since one would expect symptoms of DCI to improve with supplemental oxygen.
Now in the case of numbness you ruled out for DCI because by definition a true neurologic case DCI should have presented hours later. That is why when you feel better after oxygen you still require medical attention. As for the numbness, one could surmise medically you had a mild pinched nerve in the neck with radiculopathy that improved coincidentally while you rested and took oxygen. medically speaking you can't make the diagnosis definitively that it is for sure DCI because it is still probable that there is a chance it is something else.
Or you got very, very lucky and did not experience any permanent neurological damage from completely ignoring potentially serious DCI symptoms.
If if you go to the ER with chest pain and you are sent home with a diagnosis of heartburn that patient will tell a friend who complains of chest "don't worry, you have indigestion. Take some Tums and you'll be fine." Another patient goes to the ER and gets diagnosed with a heart attack. That patient tells his friend "You have to go to your doctor now. You might have heart disease."
When I say anecdotal experience doesn't count it's because in my experience patients loosely group their own experiences and then extrapolate that event to other similar conditions. Each individual situation is so unique you really, really can't make one experience fit all situations.
---------- Post added April 4th, 2015 at 12:45 PM ----------
Just thought of something waiting here in the airport.
Let's go back to my chest pain analogy. There is something we call pretest predictive value. If a young 20 years healthy fit individual presents to the ER with chest pain they have a low predictive suspicion for chest pain related to heart disease. More likely to be heartburn or indigestion. But if a over 60 out of shape diabetic smoker with previous history of a heart attack presents with classic chest pressure you have a very high predictive value it's heart related. But in either scenario if you give nitroglycerin for chest pain both patients might tell you they feel better. That's because indigestion might improve symptomatically with nitroglycerin too.
Going back lack to the oxygen issue. Take a diver with DCI symptoms but doesn't have DCI getting better with oxygen. No harm no foul. Take a diver with DCI symptoms who actually has DCI but whose symptoms get better with oxygen then thinks they are okay and they don't get proper care. Then hours later get a permanent injury when symptoms return. Actual harm. It's like the patient with chest pain who gets better with nitroglycerin. In the case of heartburn no harm no foul. If they are having a heart attack, start to feel better then leave the ER, possible dead patient.
I agree that the most prudent course is to report symptoms, lay on deck, breath O2, and follow DAN’s recommendations. However, the “most prudent” course is also to see a physician every time you get a headache. Unfortunately not many of us are Heads of State with a personal physician on duty in the next room.
Here’s where you lost me. I have seen several cases of apparent neurologic DCI that presented shortly after the diver emerged from the water or chamber. I say apparent because no hyperbaric doc was onboard to make an official diagnosis. It’s a good bet that it was DCI since symptoms disappeared or significantly improved at 60' on O2. A few cases didn’t get full relief until 165'.
Granted, sometimes symptoms do occur hours after surfacing — including neurologic. However, how do we actually know that DCI isn’t causing limited neurologic symptoms (presumably due to blockage of blood flow) that will clear on their own or with surface O2? That is exactly what happened most of the time in the decades before Haldane’s work. I’m not suggesting that anyone wants to go back to those terrible times in hyperbaric history, but it is misleading to imply that it doesn’t happen.
Not to downplay your point but I consider every DCI treatment to be very-very lucky when permanent damage isn’t perceptible. Until we have imaging equipment to visualize the mechanics and chemistry of DCI we are only surmising that diluent bubbles are blocking blood flow somewhere — OK, Doppler is sort of “there” but not yet definitive. Until then we depend almost entirely on antidotal evidence that we aren’t doing permanent damage.
The only magic about a chamber is we can compress the bubbles and administer O2 at 2.8 ATA… which is about as high as we dare on a regular basis. Nobody has done the human testing to know the efficacy limits of administering O2 at 1 ATA. Anecdotally we know it has some benefit but have no idea when it is adequate. There are cases when an extended Table 6 isn’t adequate.
Where I take exception is the use of the term “proper care”. The damage has already been done by the time most hyperbaric docs see DCI patients, with or without surface O2. The only real question is if that damage will heal and how much healing can be accelerated with drugs and chamber treatments. I define “proper care” as being treated in a chamber soon after symptoms first present. Treatment hours or days later is just an attempt to repair damage.
What’s my point? Keep in mind this is the Basic Forum. It is my view that several posts imply that treating decompression sickness is much more of a science than it really is. That leads to a false sense of security just as much as symptoms disappearing after breathing O2 on deck.
Here’s where you lost me. I have seen several cases of apparent neurologic DCI that presented shortly after the diver emerged from the water or chamber. I say apparent because no hyperbaric doc was onboard to make an official diagnosis. It’s a good bet that it was DCI since symptoms disappeared or significantly improved at 60' on O2. A few cases didn’t get full relief until 165'.
Granted, sometimes symptoms do occur hours after surfacing — including neurologic. However, how do we actually know that DCI isn’t causing limited neurologic symptoms (presumably due to blockage of blood flow) that will clear on their own or with surface O2? That is exactly what happened most of the time in the decades before Haldane’s work. I’m not suggesting that anyone wants to go back to those terrible times in hyperbaric history, but it is misleading to imply that it doesn’t happen.
Not to downplay your point but I consider every DCI treatment to be very-very lucky when permanent damage isn’t perceptible. Until we have imaging equipment to visualize the mechanics and chemistry of DCI we are only surmising that diluent bubbles are blocking blood flow somewhere — OK, Doppler is sort of “there” but not yet definitive. Until then we depend almost entirely on antidotal evidence that we aren’t doing permanent damage.
The only magic about a chamber is we can compress the bubbles and administer O2 at 2.8 ATA… which is about as high as we dare on a regular basis. Nobody has done the human testing to know the efficacy limits of administering O2 at 1 ATA. Anecdotally we know it has some benefit but have no idea when it is adequate. There are cases when an extended Table 6 isn’t adequate.
Where I take exception is the use of the term “proper care”. The damage has already been done by the time most hyperbaric docs see DCI patients, with or without surface O2. The only real question is if that damage will heal and how much healing can be accelerated with drugs and chamber treatments. I define “proper care” as being treated in a chamber soon after symptoms first present. Treatment hours or days later is just an attempt to repair damage.
What’s my point? Keep in mind this is the Basic Forum. It is my view that several posts imply that treating decompression sickness is much more of a science than it really is. That leads to a false sense of security just as much as symptoms disappearing after breathing O2 on deck.
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"Most supervisors would blow a diver down to 60' on O2 at the slightest hint of symptoms". ??????????????????????????????
Oxygen @ 60' that makes a PPO2 of 3. I guess that you do this in a chamber and not under water, right?
Oxygen @ 60' that makes a PPO2 of 3. I guess that you do this in a chamber and not under water, right?
2.82 ATA actually.
Exactly. This post explains it.
Oxygen Toxicity Limits & Symptoms
It is pretty interesting how these limits were derived. It was a lot more primitive than most divers imagine (see Post #4). Attached is an chart of a the US Navy Treatment Table 5. Table 6 is almost the same except there are more periods on O2.
Attachments
@Akimbo. No worries. I just wanted to make sure it was clear for everybody. In case a weirdo would find it a great idea for in water DCS treatment 
@Akimbo. No worries. I just wanted to make sure it was clear for everybody. In case a weirdo would find it a great idea for in water DCS treatment
I was wondering how long it would take for IWR (In Water Recompression) to come up.
http://www.scubaboard.com/forums/ba.../403478-recompression-chamber-under-boat.html
http://www.scubaboard.com/forums/advanced-scuba-discussions/348085-thoughts-water-recompression.html
http://www.scubaboard.com/forums/vbcms-comments/485129-article-water-recompression.html
Short Comment: IWR is far too advanced a subject for the Basic Forum but understanding it is an important exercise for all divers operating great distances from a treatment chamber.
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dumpsterDiver
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Thanks for taking the time to try to explain yourself. Most likely I WAS very lucky to have severe numbness in just the skin on my one thigh (didn't think that would be associated with a pinched nerve in my neck) and to have it resolve on oxygen and have no residual symptoms. I was pretty nervous about it, so I did my next dive solo on air to 289, just to make sure I was OK (about a week later).
As for as anecdotal stuff, does the medical field really have a lot of data that says immediate treatment with oxygen at the surface won't cure the problem in every case? How would they ever know - since the people are not seeking further medical help and thus the event would never be captured for official scientific analysis.
Since we know that the proper "official" treatment for DCI symptoms is hyperbaric oxygen therapy (and recompression), wouldn't it be entirely unethical for a medical doctor to experiment with human subjects (providing only oxygen at 1 ATM) and NOT blow them down in a chamber?
freewillie
Contributor
Unless the diver/patient has defined DCI/AGE with imaging evidence of bubbles or inferred with evidence of the tissues being damage most time the diagnosis is presumptive. Looks like a duck, quacks like a duck type of thing. But on further reflection medical professionals would prefer to over treat a percentage of "normal" patients in order to that all patients who actually do have DCI.
A different analogy is appendicitis. If it looks like appendicitis and could be appendicitis you should have surgery. It is a well accepted practice to take all suspected cases to the OR even if a few of them turn out during surgery they have a normal appendix. That would never be considered malpractice since we are taught to take all suspected cases know a small number might actually not have disease. Because the operation for a "simple" appendectomy especially if it can be done laparoscopically is preferred than letting the patient suffer a ruptured appendix which now becomes life threatening. In other words, they can die if you wait too long. So, using the previous definitions you would prefer to take a patient who has yet to rule out for disease than wait for them to rule in.
the proper treatment for DCI is a decompression chamber. The fact that a patient may have permanent damage especially in the case of neurological DCI is more a function of the severity rather than not getting treatment for a few hours or even days. If you have severe symptoms presenting on surfacing especially in light of precipitating factors like deep dive and missed deco stop you are essentially ruling in with emergent DCI. Urgent cases present around 15 min to hours after surfacing. The real tricky cases are the timely cases . Those may be mild enough diver may not seek medical tension for days. At this point you have neither ruled in but haven't really ruled out either. But if it looks like DCI and might be DCI you are going to spend time in the chamber. But keep in mind we know there will be some cases the diver didn't truly have DCI but got treated anyways. We know that, it's like the appendix analogy. Better to treat just in case.
Im not sure about numbers for actual cases, but it is a well known fact that DCI symptoms (what the patient complains of) with oxygen but the actual condition (what is causing the symptoms) still needs to be treated. And you kinda start ruling yourself in if symptoms return after you felt better with the oxygen. That's why it scares doctors patients are trying to treat and diagnose themselves with experimenting themselves.
There re is and old saying when training students. You won't always know when you are right. But you will always know when you are wrong. Better to over treat and never be wrong.
A different analogy is appendicitis. If it looks like appendicitis and could be appendicitis you should have surgery. It is a well accepted practice to take all suspected cases to the OR even if a few of them turn out during surgery they have a normal appendix. That would never be considered malpractice since we are taught to take all suspected cases know a small number might actually not have disease. Because the operation for a "simple" appendectomy especially if it can be done laparoscopically is preferred than letting the patient suffer a ruptured appendix which now becomes life threatening. In other words, they can die if you wait too long. So, using the previous definitions you would prefer to take a patient who has yet to rule out for disease than wait for them to rule in.
the proper treatment for DCI is a decompression chamber. The fact that a patient may have permanent damage especially in the case of neurological DCI is more a function of the severity rather than not getting treatment for a few hours or even days. If you have severe symptoms presenting on surfacing especially in light of precipitating factors like deep dive and missed deco stop you are essentially ruling in with emergent DCI. Urgent cases present around 15 min to hours after surfacing. The real tricky cases are the timely cases . Those may be mild enough diver may not seek medical tension for days. At this point you have neither ruled in but haven't really ruled out either. But if it looks like DCI and might be DCI you are going to spend time in the chamber. But keep in mind we know there will be some cases the diver didn't truly have DCI but got treated anyways. We know that, it's like the appendix analogy. Better to treat just in case.
Im not sure about numbers for actual cases, but it is a well known fact that DCI symptoms (what the patient complains of) with oxygen but the actual condition (what is causing the symptoms) still needs to be treated. And you kinda start ruling yourself in if symptoms return after you felt better with the oxygen. That's why it scares doctors patients are trying to treat and diagnose themselves with experimenting themselves.
There re is and old saying when training students. You won't always know when you are right. But you will always know when you are wrong. Better to over treat and never be wrong.
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