Diving May Damage Blood Vessels
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Jax,
In theory, repeated insults and repairs to the endothelium could lead to thickening and stiffening. That said, it's possible that the author may have found an interesting phenomenon that has no real effect on overall health. In the other thread, Lulubelle made the point that until events like those described in the study can be associated with measurable outcomes like coronary artery disease, the author's conclusion that air is safer than nitrox is premature. The only way to really prove that would be to measure long-term outcomes in divers who use nitrox vs. those in divers who use only air.
Another point to consider is that many divers experience silent venous bubbles after a dive. Bubbles are also known to cause damage to the vascular endothelium, and most venous bubbles end up in the pulmonary capillaries. If multiple small insults to the pulmonary capillaries from venous bubbles caused long-term damage to the endothelium, we would probably see issues like pulmonary hypertension and impaired gas exchange in experienced divers, and I'm not aware of any studies that have shown that nor of any anecdotal evidence. IMHO, the moral is: don't throw away your nitrox just yet.
Cheers,
DDM
In theory, repeated insults and repairs to the endothelium could lead to thickening and stiffening. That said, it's possible that the author may have found an interesting phenomenon that has no real effect on overall health. In the other thread, Lulubelle made the point that until events like those described in the study can be associated with measurable outcomes like coronary artery disease, the author's conclusion that air is safer than nitrox is premature. The only way to really prove that would be to measure long-term outcomes in divers who use nitrox vs. those in divers who use only air.
Another point to consider is that many divers experience silent venous bubbles after a dive. Bubbles are also known to cause damage to the vascular endothelium, and most venous bubbles end up in the pulmonary capillaries. If multiple small insults to the pulmonary capillaries from venous bubbles caused long-term damage to the endothelium, we would probably see issues like pulmonary hypertension and impaired gas exchange in experienced divers, and I'm not aware of any studies that have shown that nor of any anecdotal evidence. IMHO, the moral is: don't throw away your nitrox just yet.
Cheers,
DDM
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The following are from (1) Richard Vann, Ph.D., a DAN Research Consultant and well-known and widely-published researcher on diving physiology and medicine and (2) and John U. Lee, a DAN medical information specialist.
1. From Dr. Vann:
These studies apply sensitive measurements that are relatively new to diving and seem to detect stress responses that were hitherto unknown. Drs Neal Pollock and Petar Denoble (DAN Researchers) are presently in Europe working with Zeljko Dujic to collect dive profiles and blood for microparticle (MP) analysis.
The research in this area is certainly interesting and bears following, but the clinical significance of these findings remains in question. I wonder whether other stresses such as heat or exercise induce similar findings. Diving has been conducted for over 100 years, and I know of no evidence in humans associating diving with cardiovascular or endothelial damage that is clinically important.
Cardiovascular health is a significant problem in diving, however [i.e. greater risk of a diving related fatality in those divers with preexisting CV conditions] . Four papers from the diving fatality workshop concerning CV health will be published in the Jul-Aug issue of UHM and address occult heart disease, the major problem.
2. From Mr. Lee:
Thank you for your recent inquiry regarding the recent abstract presentation on endothelial function and diving. DAN is aware of this phenomenon and is engaged with researchers in diving medicine to help flush out the processes involved. Two of our researchers are presently in Croatia studying microparticles in divers a trip prompted by a recent publication and collaborative opportunity with the hyperbaric and environmental physiology department at the University of Pennsylvania. DANs research involvement is being done in collaboration with researchers at the University of Split in Croatia.
The ultimate question is whether diving causes progressive or lasting endothelial damage that promotes or accelerates arterial disease. At present, the findings from research done at DAN on diving mortality, does not find an association between diving and arterial disease, but our work has been largely aimed at fatalities that occur while diving. Our diving fatality data indicates an association with underlying heart disease in about 25-30% of cases. These fatality statistics are consistent with the general population and do not indicate an increased or unique diving related risk. Said a slightly different way, the data neither supports nor suggests that divers are at a higher risk for arterial disease than the general population. Nonetheless, the potential link between diving and endothelial damage and the potential impact on general health is an interesting question.
The research on diving and endothelial function, looking at arterial flow rates is indeed intriguing, but we need to keep in mind that diving is not the only activity that may impact vascular function or provide physiological stress. We should also remain mindful that physiological responses do not necessarily equate to disease, trauma or future dysfunction. The real question is whether diving puts us at an increased risk of heart disease (the primary cause of death in this country). This is a question we just dont have an answer to, but it is reasonable to say that the diving population has not suffered from a predisposition toward early death or heart/artery disease based on the data available.
At present, neither Dr. Vann nor I are aware of any association between diving and endothelial disruption that results in clinical findings or health risks. As he states, current research is underway to more fully explore this topic and we will all watch with interest.
At present DAN doesnt have a stance as there just isnt enough data to support concern about dive safety or personal health. This is an issue that we are actively engaged in and will continue to monitor.
Regards,
DocVikingo
1. From Dr. Vann:
These studies apply sensitive measurements that are relatively new to diving and seem to detect stress responses that were hitherto unknown. Drs Neal Pollock and Petar Denoble (DAN Researchers) are presently in Europe working with Zeljko Dujic to collect dive profiles and blood for microparticle (MP) analysis.
The research in this area is certainly interesting and bears following, but the clinical significance of these findings remains in question. I wonder whether other stresses such as heat or exercise induce similar findings. Diving has been conducted for over 100 years, and I know of no evidence in humans associating diving with cardiovascular or endothelial damage that is clinically important.
Cardiovascular health is a significant problem in diving, however [i.e. greater risk of a diving related fatality in those divers with preexisting CV conditions] . Four papers from the diving fatality workshop concerning CV health will be published in the Jul-Aug issue of UHM and address occult heart disease, the major problem.
2. From Mr. Lee:
Thank you for your recent inquiry regarding the recent abstract presentation on endothelial function and diving. DAN is aware of this phenomenon and is engaged with researchers in diving medicine to help flush out the processes involved. Two of our researchers are presently in Croatia studying microparticles in divers a trip prompted by a recent publication and collaborative opportunity with the hyperbaric and environmental physiology department at the University of Pennsylvania. DANs research involvement is being done in collaboration with researchers at the University of Split in Croatia.
The ultimate question is whether diving causes progressive or lasting endothelial damage that promotes or accelerates arterial disease. At present, the findings from research done at DAN on diving mortality, does not find an association between diving and arterial disease, but our work has been largely aimed at fatalities that occur while diving. Our diving fatality data indicates an association with underlying heart disease in about 25-30% of cases. These fatality statistics are consistent with the general population and do not indicate an increased or unique diving related risk. Said a slightly different way, the data neither supports nor suggests that divers are at a higher risk for arterial disease than the general population. Nonetheless, the potential link between diving and endothelial damage and the potential impact on general health is an interesting question.
The research on diving and endothelial function, looking at arterial flow rates is indeed intriguing, but we need to keep in mind that diving is not the only activity that may impact vascular function or provide physiological stress. We should also remain mindful that physiological responses do not necessarily equate to disease, trauma or future dysfunction. The real question is whether diving puts us at an increased risk of heart disease (the primary cause of death in this country). This is a question we just dont have an answer to, but it is reasonable to say that the diving population has not suffered from a predisposition toward early death or heart/artery disease based on the data available.
At present, neither Dr. Vann nor I are aware of any association between diving and endothelial disruption that results in clinical findings or health risks. As he states, current research is underway to more fully explore this topic and we will all watch with interest.
At present DAN doesnt have a stance as there just isnt enough data to support concern about dive safety or personal health. This is an issue that we are actively engaged in and will continue to monitor.
Regards,
DocVikingo
Thanks, Doc! That was my take on it, but it's nice to hear it supported by people who are much more involved with the research than I am.
One must always remember that damage and repair can be a negative OR a positive thing, depending on the ultimate net effect. (For example, chemical peels of facial skin are done to induce a repair process that results in reduced total damage.)
One must always remember that damage and repair can be a negative OR a positive thing, depending on the ultimate net effect. (For example, chemical peels of facial skin are done to induce a repair process that results in reduced total damage.)
OP
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MKC
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Is it possible that Nitrox is harmful to you?
Check this out.
Medical News: EuroPRevent: Diving May Damage Blood Vessels - in Meeting Coverage, EuroPRevent from MedPage Today
Check this out.
Medical News: EuroPRevent: Diving May Damage Blood Vessels - in Meeting Coverage, EuroPRevent from MedPage Today
FWADIVER
Contributor
meaningless study, all they are seeing is the markers and drawing conclusions based on that. also the sample is terrible, navy divers only? Typical research-media cycle
PHD Comics: Science News Cycle
PHD Comics: Science News Cycle
ianr33
Contributor
Lot less harmful than getting bent. 
This study was discussed in another thread: http://www.scubaboard.com/forums/diving-medicine/378848-diving-may-damage-blood-vessels.html
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