DAN Live Chat (Including Transcript) from 9/25/2012

DiverDAN · Sep 13, 2012

DAN will be hosting a live chat in the ScubaBoard chat rooms on Sept. 25 from 2-3 p.m. ET. The chat will be led by DANs Chief Medical Officer Dr. Nick Bird and he will field questions on the topic Demystifying Hyperbaric Oxygen Therapy. Join us in the DAN HBOT chat room to have your questions about hyperbaric treatment for decompression illness addressed. This fully moderated chat will host up to 50 participants for a round table discussion.

HowardE · Sep 25, 2012

Thanks to DAN and Dr. Nicholas Bird for taking the time to host the chat today. Here is the transcript of today's Chat.

2012-09-25 13:46:15

A ScubaBoard Staff Message...
HowardE -> Welcome to the DAN Live chat with Dr Nicholas Bird. This is a fully moderated chat, which means that all messages posted will be placed in a moderation queue. This will allow Dr. Bird time to answer the questions in an orderly fashion.

2012-09-25 14:05:12

A ScubaBoard Staff Message...
nickbird -> Hyperbaric medicine is a medical specialty and treatment modality that can be used for all ages and there is a long list of approved indications. The most common indications include: diabetic foot ulcers, delayed effects of radiation therapy, selected problem wounds and compromised flaps and grafts. Other common indications include: carbon monoxide poisoning, decompression sickness, arterial gas embolism and acute arterial insufficiency.

2012-09-25 14:05:59

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thatdiveguy -> hello

2012-09-25 14:07:09

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scubameg -> Does anyone have any questions for Dr. Bird?

2012-09-25 14:08:05

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nickbird -> Hyperbaric medicine is provided in one of two chamber types: monoplace (one person) and multiplace (more than one person). Each of these chamber types provides equally effective treatment and can be used for all approved indications.

2012-09-25 14:09:13

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thatdiveguy -> so what about hyperbaric medicine usually mistifies people?

2012-09-25 14:11:55

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nickbird -> The most common question relates to the approved indications, i.e., what hyperbaric oxygen therapy is used for. The other question people often have is how long are treatments (both per treatment and overall treatment course duration).

2012-09-25 14:14:02

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thatdiveguy -> I like that question, so how do they determine how long a person needs to be in a chamber when they get bent?

2012-09-25 14:15:42

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HowardE -> Good Question. Please stand by while Dr. Bird responds.

2012-09-25 14:16:43

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nickbird -> Great question. Most dive accidents are treated initially with a USN/USAF Treatment Table 6 (TT6). This treatment protocol starts at 2.8ATA. A TT6 can be extended or repeated depending on patient status. Repetitive treatments, following a TT6 may be shorter. Commonly, we treat to the point of therapeutic plateau - where patient symptoms stop improving with additional treatments.

2012-09-25 14:17:35

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Cert1967 -> nickbird The forum often reports on treatment that is delayed due to denial of underlying injury. What are the diagnostic keys for treatment.

2012-09-25 14:20:57

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nickbird -> There are three essential aspects to the diagnosis of DCS: 1. Nature of the dive (was it provocative or did the person push the no-deco limits), 2. When did symptoms start following the dive(s) and 3. What is the nature of symptoms and are they consistent with DCS? Each of these points is important and may provide good insight into the likelihood of DCS as the primary diagnosis. DCS is a clinical diagnosis for which there is no definitive test, so history and presenting signs and symptoms are very important.

2012-09-25 14:21:44

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thatdiveguy -> I understand why hyperbaric therapy helps for divers when they're bent, but how does it make a difference in cases such as carbon monoxide poisoning over just giving them o2 at normal pressure?

2012-09-25 14:23:17

A ScubaBoard Staff Message...
HowardE -> Welcome to our new users. Thanks for your patience as Dr. Bird types his responses.

2012-09-25 14:25:00

A ScubaBoard Staff Message...
nickbird -> Great question. The role of hyperbaric oxygen therapy (100% oxygen delivered under pressure) does two primary things in CO poisoning. It increases oxygen delivery to tissues via plasma (Henry's law where oxygen is dissolved into plasma) and also reduces the systemic inflammatory response the CO poisoning creates. This model is also applied for DCS which is largely due to inflammation, which presents and may persist even when bubbles are gone. In addition, the administration of oxygen also serves to displace CO and expedite its removal.

2012-09-25 14:25:48

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Noonan -> Okay, here is a silly question for you. My "friend" spent 2 days in the chamber. How many dives does "she" get to count in her log?

2012-09-25 14:26:17

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HowardE -> I think we all know the answer to that one...

2012-09-25 14:26:21

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Scott -> We often hear that stresses of cold water diving can increase the risk of DCS. What about the opposite? Can diving in extremely warm water increase the risk as well. I ask because we often dive in geothermal lakes where the temps could be as high as 95+ degrees F.

2012-09-25 14:28:36

A ScubaBoard Staff Message...
nickbird -> Interesting question. I am not aware of any data to support the notion that hot water exposure actually leads to a higher incidence of DCS. One of the confounders is that these lakes are often at altitude or in locations where altitude excursions follow the dive. This makes a clear cause and effect relationship difficult to confidently state.

2012-09-25 14:30:59

A ScubaBoard Staff Message...
nickbird -> Please note that my answer is separate from the literature which talks about the potential benefit of warm water exposure during decompression and the possible increase in DCS with warm water exposure following a dive (hot tubs). The geothermal question relates to warm water exposure throughout the dive and is thus answered with some caution and should be viewed differently than these other scenarios.

2012-09-25 14:31:41

A ScubaBoard Staff Message...
HowardE -> Follow up question regarding TT6. Does the 60 depth relate to a 60 decompression stop? What if the diver is bent and would be required to make deeper stops? Is TT6 going to get them deep enough to re-compress the bubbles and eventually offgas them?

2012-09-25 14:34:34

A ScubaBoard Staff Message...
nickbird -> The treatment depth of a TT6 enables the optimal combination of oxygen and pressure. The utilization of 100% oxygen optimizes the diffusion gradient and the pressure both enhances oxygen delivery to tissues and reduces systemic inflammation. The impact of Boyle's law, with respect to shrinking bubbles is minimally improved at deeper depths. In addition, most excursions to deeper depths require a reduced oxygen gradient. It is this gradient that has the greatest influence in bubble size reduction and off gassing of inert gas.

2012-09-25 14:34:51

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thatdiveguy -> In theory could hyperbaric therapy be used to cheat in sports? Massively increase the amount of oxygen available to the body right before doing something such as running?

2012-09-25 14:37:00

A ScubaBoard Staff Message...
nickbird -> In theory yes. I am unaware of any data which compares the impact on athletic performance or endurance subsequent to HBOT. Elevated oxygen levels can persist, but we wouldn't expect this to last very long and is therefore not too likely to make a marked difference in performance.

2012-09-25 14:37:28

A ScubaBoard Staff Message...
Cert1967 -> Many cases of DCS happen in 3rd world countries - often in remote locations - where chambers may not be staffed on a 24 hr cycle. The patient and companions would likely know little of the doc's qualifications and experience. What role does DAN play in assisting the local doc with treatment protocol, and how good are the docs on site?

2012-09-25 14:40:55

A ScubaBoard Staff Message...
nickbird -> Great question. Part of DAN's value in such settings is to enhance the combination of patient complaints to facility capacity. DAN doesn't have control over physician credentials or expertise, but we certainly try to steer people towards good facilities. We also involve external diving medicine experts from UC San Diego and U Penn to ensure that treating physicians receive as much support as possible and that DAN remains objective. Our goal is good patient care and we want to ensure that this care and the advice provided is done objectively and by experts with whom we have confidence.

2012-09-25 14:44:21

A ScubaBoard Staff Message...
JohnN -> When diving EAN, a great deal of attention is paid to the PO2 and its limitation on the MOD. It seems during a decompression cycle, PO2's will go much much higher. I know CNS convulsions are bad at depth, are they less severe in a Deco chamber? In your experience how often do you see CNS convulsions in the chamber?

2012-09-25 14:44:29

A ScubaBoard Staff Message...
nickbird -> To add to the last answer...there are times when divers are treated without our knowledge or undergo treatment (either duration or number of treatments) that may not be necessary. There are other times when treatments or the treating physicians neglect other causes for symptoms than Decompression Illness. It is for these reasons that we encourage people to call us and to help us do all we can for you.

2012-09-25 14:48:10

A ScubaBoard Staff Message...
nickbird -> Great question about acute CNS oxygen toxicity. In short, CNS toxicity in a chamber is rare. The critical difference between a chamber and divers, is that a seizure underwater is likely fatal. We can tolerate higher PO2 in a chamber because it is a controlled environment. Oxygen toxicity comes in two essential forms: pulmonary and CNS a. For patients undergoing daily HBOT for 90 minutes, this has not been demonstrated as a concern. b. Patients are at a small risk for CNS toxicity. Initial estimates placed this risk at 1:10,000 treatments (0.01%) c.More recent data places it closer to 1:30,000 (0.03%) d. Review of DCI, places the risk at 0.6% e. For CO the risk is approximately 1.8%

2012-09-25 14:48:26

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thatdiveguy -> I know when treating certain illnesses people will go in for multiple dives in the chamber. Do they have divers do this for DCS? or do they just stay in the chamber until they're good to go?

2012-09-25 14:52:10

A ScubaBoard Staff Message...
nickbird -> In cases of DCS, one or more treatments may be necessary. This decision is based on the patient's condition. If as a for instance, a diver experiences complete symptom resolution during their initial treatment, we may not treat more than once. Treatments are usually spaced out (time in-between). The duration of time in-between is dependent on symptom severity and staff availability. Some centers may only be able to treat once a day, others may be able to treat multiple times a day. Bent divers do not stay in the chamber continuously. They get out after treatments are concluded.

2012-09-25 14:53:04

A ScubaBoard Staff Message...
HowardE -> Do we have any other questions for Dr. Bird, before we wrap things up?

2012-09-25 14:53:47

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HowardE -> Comments on the questions asked?

2012-09-25 14:55:18

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thatdiveguy -> if DCS is due to bubbles, why would you not keep them in continuously until everything is cleared?

2012-09-25 14:59:23

A ScubaBoard Staff Message...
nickbird -> Great question. Bubbles do indeed appear as integral to DCS, but symptoms appear and persist long after bubbles are gone. Therefore, bubbles are only one part of the equation. After a single TT6, the bubbles are gone. All excess nitrogen (or helium) is also gone. So for that reason there is no added benefit from continued pressure exposure. The other reasons include: pulmonary oxygen toxicity, which starts to become a concern with prolonged treatments and patient/staff fatigue. A TT6 is about 5 hours. If extended it can go to more than 6h. This is a long time. We also like to have time in between to assess a patient's response to therapy.

2012-09-25 15:01:08

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scubameg -> I am really impressed with the quality of questions and answers. I look forward to the next live chat.

2012-09-25 15:01:34

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HowardE -> One last question...

2012-09-25 15:01:36

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thatdiveguy -> what would cause symptoms to persist after the bubbles are gone?

2012-09-25 15:04:23

A ScubaBoard Staff Message...
nickbird -> Great question. Research is demonstrating that bubbles are part of the DCS symptom cascade, but aren't the whole picture. It appears as though bubbles may induce inflammation which can result in tissue swelling, tissue damage, white blood cell activation, and release of inflammatory / tissue damaging components and tissue death. These processes are mitigated by HBOT and may persist after bubbles are gone and excess inert gas removed.

2012-09-25 15:04:50

A ScubaBoard Staff Message...
HowardE -> We've reached the end of our allotted time with Dr. Bird.

2012-09-25 15:04:55

A ScubaBoard Staff Message...
HowardE -> Thanks to those of you who posted questions here in our first hosted chat on ScubaBoard with our special guest Dr. Nicholas Bird, Chief Medical Officer for DAN. We look forward to our next live chat.

2012-09-25 15:05:14

A ScubaBoard Staff Message...
HowardE -> The transcript of this chat will be posted on DAN's site, and here on SB.

DAN Live Chat (Including Transcript) from 9/25/2012

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