venturead 0 #1 September 23, 2007 Quote(I gotta think that embolic events e.g. TIA or true Stroke a.k.a. cerebral vascular accidents or CVA's would be relatively common on rapid ascent to altitude in an unpressurized environment (skydiving plane) and/or descent--freefall.) There is no evidance that emboli evenits are more common with changes in pressure. (change in pressure CAUSES emboli. Hence "The Bends." The bends is a recognized physiologic syndrome as a result of rapid pressure change on a person. Skydiving at altitude has the same effect in "reverse.")_ Simply not true. The only significance "the bends" has to skydiving is if you go to altitude within 24 hours of having breathed air at an atmospheric pressure higher than one atmosphere. The reason people get the bends is that the nitrogen in air breathed under pressure gets dissolved in the tissues and needs to get released from the tissues over time. Hence dive tables. If you haven't been breathing air at higher than normal atmospheric pressure, you won't have nitrogen bubbles in your blood at the altitudes recreational skydivers play. (It is also probably not well studied in the skydiving environment. Informed speculation would assume 1. Embolic events are more frequent with rapid altitude change than at stable atmospheric pressure.) When you assume, you make an "ass" of "u" and "me" and would be wrong in this case. No evidence to support a higher rate of embolic strokes in rapid altitude change. You can make a reasonable argument that there may be more hypertensive strokes (elevation of blood pressure) or hemorrhagic strokes from the elevation of blood pressure associated with the adrenaline release from skydiving."You can't skydive if you are sitting on the couch at home." Richard "the C" Eddy Quote Share this post Link to post Share on other sites headcase 0 #2 September 23, 2007 Quote When you assume, you make an "ass" of "u" and "me" and would be wrong in this case. No evidence to support a higher rate of embolic strokes in rapid altitude change. I'm not gonna start anything. What you say is true. "There is no evidence..." Evidence is hard to come by.... But here is a quote: "# Magnitude of the pressure reduction: A large pressure reduction is more likely to cause DCS than a small one. For example, the ambient pressure halves by ascending during a dive from 10 metres / 33 feet (2 bar) to the surface (1 bar), or by flying from sea level (1 bar) to an altitude of 16,000 feet / 5,000 metres (0.5 bar) in an un-pressurized aircraft. Diving and then flying shortly afterwards increases the pressure reduction as does diving at high altitude. # Repetitive exposures: Repetitive dives or ascents to altitudes above 18,000 feet within a short period of time (a few hours) also increase the risk of developing altitude DCS. # Rate of ascent: The faster the ascent, the greater the risk of developing altitude DCS. An individual exposed to a rapid decompression (high rate of ascent) above 18,000 feet has a greater risk of altitude DCS than being exposed to the same altitude but at a lower rate of ascent. # Time at altitude: The longer the duration of the flight to altitudes of 18,000 feet and above, the greater the risk of altitude DCS. # Age: There are some reports indicating a higher risk of altitude DCS with increasing age." So it is a matter of degree. To think that this cannot occur with rapid pressure changes from let's say 10k to 15k would to negate the concept of bell-shaped curve which in nature is the rule not the exception. Lastly I can assure you tugging on membranes will dislodge an emboli. What do you think happens with all the jukin' and jivin' with ascent/descent/freefall/ BP/HR/ etc. Again you're probably correct in that I know very little.... Quote Share this post Link to post Share on other sites headcase 0 #3 September 23, 2007 DCS- http://en.wikipedia.org/wiki/Decompression_sickness Remember after reading this well written "for public consumption" overview that DCS is only tagged when symptoms are apparent not when let's say an emboli develops whcih also resolves spontaneuosly and is otherwise asymptomatic.... ________________________________________________ My condolences to friends and family. I will say no more. Quote Share this post Link to post Share on other sites Join the conversation You can post now and register later. If you have an account, sign in now to post with your account. Note: Your post will require moderator approval before it will be visible. Reply to this topic... × Pasted as rich text. Paste as plain text instead Only 75 emoji are allowed. × Your link has been automatically embedded. Display as a link instead × Your previous content has been restored. Clear editor × You cannot paste images directly. Upload or insert images from URL. Insert image from URL × Desktop Tablet Phone Submit Reply 0
headcase 0 #2 September 23, 2007 Quote When you assume, you make an "ass" of "u" and "me" and would be wrong in this case. No evidence to support a higher rate of embolic strokes in rapid altitude change. I'm not gonna start anything. What you say is true. "There is no evidence..." Evidence is hard to come by.... But here is a quote: "# Magnitude of the pressure reduction: A large pressure reduction is more likely to cause DCS than a small one. For example, the ambient pressure halves by ascending during a dive from 10 metres / 33 feet (2 bar) to the surface (1 bar), or by flying from sea level (1 bar) to an altitude of 16,000 feet / 5,000 metres (0.5 bar) in an un-pressurized aircraft. Diving and then flying shortly afterwards increases the pressure reduction as does diving at high altitude. # Repetitive exposures: Repetitive dives or ascents to altitudes above 18,000 feet within a short period of time (a few hours) also increase the risk of developing altitude DCS. # Rate of ascent: The faster the ascent, the greater the risk of developing altitude DCS. An individual exposed to a rapid decompression (high rate of ascent) above 18,000 feet has a greater risk of altitude DCS than being exposed to the same altitude but at a lower rate of ascent. # Time at altitude: The longer the duration of the flight to altitudes of 18,000 feet and above, the greater the risk of altitude DCS. # Age: There are some reports indicating a higher risk of altitude DCS with increasing age." So it is a matter of degree. To think that this cannot occur with rapid pressure changes from let's say 10k to 15k would to negate the concept of bell-shaped curve which in nature is the rule not the exception. Lastly I can assure you tugging on membranes will dislodge an emboli. What do you think happens with all the jukin' and jivin' with ascent/descent/freefall/ BP/HR/ etc. Again you're probably correct in that I know very little.... Quote Share this post Link to post Share on other sites
headcase 0 #3 September 23, 2007 DCS- http://en.wikipedia.org/wiki/Decompression_sickness Remember after reading this well written "for public consumption" overview that DCS is only tagged when symptoms are apparent not when let's say an emboli develops whcih also resolves spontaneuosly and is otherwise asymptomatic.... ________________________________________________ My condolences to friends and family. I will say no more. Quote Share this post Link to post Share on other sites
