A question about hyperbaric oxygen therapy

[boulderjohn]

I have long had a question that I finally asked at the tail end of a long thread, and I decided I would ask it again in this forum where it can get the attention of knowledgeable medical minds.

When a friend of mine got bent and had to go through a serious of hyperbaric treatments, he was never alone in the chamber. Others were getting treatments as well, but none of them were being treated for anything related to diving. In fact, many hospitals with hyperbaric chambers will not treat DCS victims, reserving their use for patients with a wide variety of other ailments. When he played with the Denver Broncos, linebacker Bill Romanowski owned his own chamber and used it to speed recovery after every game. Here are some highly reputable medical web sites describing the benefits to the healing body of hyperbaric oxygen therapy (HBOT):

Hyperbaric oxygen therapy - Mayo Clinic
https://www.nlm.nih.gov/medlineplus/ency/article/002375.htm
Medscape: Medscape Access
Hyperbaric Oxygen Therapy for Wound Healing | Johns Hopkins Medicine Health Library

So there does not seem to be any question that HBOT provides great benefits to bodies healing from a wide variety of ailments. In contrast, conventional thinking is that breathing elevated levels of oxygen by diving with nitrox provides no such benefit whatsoever. Can anyone explain why inhaling elevated oxygen under pressure has such well proven benefits when done in a hyperbaric chamber, yet it has no such effect when done under water?

 

[knotical]

Is it conventional thinking or lack of documented evidence? I've long believed as you apparently do that of course it provides similar benefit.
Scuba diving is largely done by healthy individuals. Those patients who undergo HBOT are generally unable to scuba dive (and/or uninterested). These factors might make funding for studies hard to come by.

---------- Post added September 12th, 2015 at 07:46 AM ----------

some teasers:

Scuba diving may hold promise for paraplegics - tribunedigital-baltimoresun

Scuba Diving Improves Function of Body, Mind in Vets with Spinal Cord Injury - 09/17/2011

 

[JohnnyC]

So there does not seem to be any question that HBOT provides great benefits to bodies healing from a wide variety of ailments. In contrast, conventional thinking is that breathing elevated levels of oxygen by diving with nitrox provides no such benefit whatsoever. Can anyone explain why inhaling elevated oxygen under pressure has such well proven benefits when done in a hyperbaric chamber, yet it has no such effect when done under water?

In what regard? Nitrox exposure while diving is generally short, whereas a chamber ride is quite a long experience, and generally more than one treatment. What are you expecting from a short exposure of only slightly oxygen-enriched air? If someone needs HBOT, I'm not sure they would be healthy enough to be in a position where a little nitrox in an underwater environment would be an acceptable treatment.

If you are talking about in-water recompression, the Navy has done so for quite a while, as well as several certifying agencies offering courses of study. That's a whole different ball game however.

Here's a Navy Table 6, look at the length of time at which a patient is being treated with pure oxygen at high pressure. In comparison, nitrox has relatively low oxygen content in comparison, and at a relatively short duration.

 

[g2]

Pure oxygen at 2.8 atm absolute (60 ft) in a chamber will provide a PPO2 of 2.8. Divers, of course, avoid those levels due to oxygen toxicity concerns; these can be better managed in a chamber because the patient is not physically active (which might increase susceptibility) and stands no chance of drowning.

Diving near the 1.6 PPO2 limit should, in theory, promote similar healing as HBOT, but it won't be as effective due to the limited exposure time and lower PPO2 level.

Edit and caveat: Some wounds that lack proper perfusion may respond better to ambient O2 at pressure rather than inspired O2. Diving would be ineffective for that kind of treatment unless, perhaps, you wear a drysuit filled with nitrox...

 

[Duke Dive Medicine]

John,

The O2 toxicity element has been pointed out above but is worth reiterating. We treat at a minimum of 33 fsw, or 2.0 ATA, for two hours, which would exceed the recommended inspired pO2 for diving. Below 2.0 ATA is probably subtherapeutic. Re the football player, there's some evidence that HBO2 is good for accelerating recovery from soft tissue injuries but for we mere mortals (and our health insurance companies) it's too much to pay to fix a sprained ankle. The Japanese national soccer team's physician staff has done a lot of work with it - they came and gave us a grand rounds a couple of years ago. FWIW the one (retired) pro football player I know well has never seen anybody use a hyperbaric chamber.

The number of treatments a patient gets depends on what he or she is being treated for. About 80% of the patients we see at Duke have some form of delayed injury from therapeutic radiation. Those patients typically receive between 30 and 60 treatments at 2.0 ATA. The therapeutic benefit of HBO2 is derived from increasing the delivery of O2 to the radiation-damaged tissues, which often have impaired circulation due to capillary damage. This helps the body form new capillaries in the area and enables the patient to heal. Other things we see with some frequency are severe diabetic foot ulcers, compromised tissue flaps and grafts, and refractory osteomyelitis.

DCS is a more acute indication. Divers are treated until they either get completely better or their symptoms don't improve with further hyperbaric treatment. Often they'll resolve after one treatment at 2.82 ATA. If not then the treatment is very individual. We may repeat a Table 6, put them on a shorter table 5, and/or put them in with the regular patients at 2 ATA. That's probably why your friend was in with other people who didn't have DCS.

Best regards,
DDM