Doug_Davis 0 #1 February 25, 2014 So flew down to Deland this past weekend for a canopy course and to demo a Storm from PD. Friday and Saturday we didnt get in jumps in due to cloud cover. Sunday they managed to get 3 or 4 loads up I think, before showers and tornado called a halt to DZ ops. On my first jump of the day I was demoing the Storm. Did a hop and pop at 5k. I was lead jumper on second pass. Leaning out door watching prior pass with no problems. Green light came on, I scanned below me one final time and out I went. Caught relative air, gave it a two count and deployed my PC. The chute opened smoothly, although I do remember something smacking my right foot (d-bag) during deployment. As soon as I got under canopy my vision started going black at the edges and my stomach started doing flips (nausea). It was all I could do to shake it off and stay conscious. Made it to the ground and landed without incident. Although I stayed light headed for about an hour after the incident. I cant figure out what caused it. I didnt head strike anything that Im aware of. I had been pissing all morning and was hydrated. I ate breakfast. I hadnt been drinking the night before. My leg straps were snug but once under canopy I was able to adjust them into a seated position so not that tight. Any ideas? Other than my first jump at airborne school and getting shot at under canopy this jump definitely had me puckered up. The idea of passing out at 4.6k or so and ending up God knows where gave me the willies. Quote Share this post Link to post Share on other sites
NWFlyer 2 #2 February 25, 2014 Happened to me several years ago and I actually passed out; best we could figure was that I'd shifted in the harness enough to impact blood flow to my legs. (thread here: http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=1778924;) However, my symptoms were a bit different - once I was back on the ground other than being a little shaken by the experience, I felt (physically) just fine. (Edit to add: I got a full medical workup after the incident to ensure nothing more serious was going on. Be sure to take internet medical advice with a big grain of salt... it's worth exactly what you pay for it)."There is only one basic human right, the right to do as you damn well please. And with it comes the only basic human duty, the duty to take the consequences." -P.J. O'Rourke Quote Share this post Link to post Share on other sites
BigMikeH77 0 #3 February 25, 2014 QuoteAs soon as I got under canopy my vision started going black at the edges and my stomach started doing flips (nausea). It was all I could do to shake it off and stay conscious. Made it to the ground and landed without incident. I've had this happen before as well, on a rental rig - the leg straps were just snug enough to restrict blood flow from around the femoral artery (and its complex network of piping). Same situation... I had a little food in me, hop n pop on first jump of the day, everything is fine until I'm in the saddle. Really, it took everything I had to not pass out. I was seeing green and stars and would have been content to just throw up everywhere. But once I was on the ground and relaxed, breathed, took the rig off, and talked about it for a short bit, I was just fine. Quote Share this post Link to post Share on other sites
jimmytavino 16 #4 February 25, 2014 is there any chance, that within the hour prior to the jump, you may have had an "energy drink", or Two??? those can hit, all at once and give symptoms like you described.. glad you were Ok. Quote Share this post Link to post Share on other sites
DrDom 0 #5 February 25, 2014 I have to say this is a very interesting topic. Assuming it is the leg straps I'm not sure why compressing the artery would be the issue. 2 arteries to the legs, no more no less. If you clamp them you then would just redirect blood flow around the body like when we cross-clamp an aorta during trauma to save the heart and brain. Maybe the real pathology is actually the femoral veins being compressed. You would then have flow INTO the legs but there would be no return, it would starve the voena cava and decrease preload which would lower cardiac output under Starling's law, and you could black out. Fascinating, I wonder how one would even study it... maybe I could get a hanging harness and try it...You are not the contents of your wallet. Quote Share this post Link to post Share on other sites
dzswoop717 5 #6 February 25, 2014 I had this happen to me during a boogie in NC about 15 years ago. My episode happened in freefall, I had a very shakey canopy ride and fell flat on my face during landing. I couldn't even stand up once back on earth. It was one of those extremely hot southern days. I contribute the whole thing to dehydration. I was down for a couple of hours after that jump drinking water and laying in my airconditioned office. Scary and eye opening. I make sure I stay hydrated during all my aviation activities these days. Quote Share this post Link to post Share on other sites
Doug_Davis 0 #7 February 25, 2014 jimmytavinois there any chance, that within the hour prior to the jump, you may have had an "energy drink", or Two??? those can hit, all at once and give symptoms like you described.. glad you were Ok. Nope. Dont do those anymore. I'm strictly a morning coffee guy. Quote Share this post Link to post Share on other sites
dthames 0 #8 February 25, 2014 During an early student SL jump, i dearched reaching for a practice pull. After the canopy opened, I was confused on why I had suddenly got motion sick. Someone had video of the exit and it was clear I was whipped around pretty hard during the deployment. I get motion sick, so I was not surprised after seeing the video. But I didn't really have a clear sense of what happened until I did see the video.Instructor quote, “What's weird is that you're older than my dad!” Quote Share this post Link to post Share on other sites
Doug_Davis 0 #9 February 25, 2014 DrDomI have to say this is a very interesting topic. Assuming it is the leg straps I'm not sure why compressing the artery would be the issue. 2 arteries to the legs, no more no less. If you clamp them you then would just redirect blood flow around the body like when we cross-clamp an aorta during trauma to save the heart and brain. Maybe the real pathology is actually the femoral veins being compressed. You would then have flow INTO the legs but there would be no return, it would starve the voena cava and decrease preload which would lower cardiac output under Starling's law, and you could black out. Fascinating, I wonder how one would even study it... maybe I could get a hanging harness and try it... Interesting hypothesis. A little comforting to know I'm not the only one. Seems its happened to a few of us. So wonder if it would be worth a write up in a safety article in Parachutist to warn people about. Quote Share this post Link to post Share on other sites
pchapman 261 #10 February 25, 2014 On the subject of harness pressure, which is one possibility when it comes to Doug's unexpected problem: The issue of going unconscious or worse from being suspended in a harness is a known one. I've seen it categorized as "Hanging Harness Syndrome" A quote from a paper abstract uses other wording too: QuoteSuspension trauma (also known as “harness-induced pathology” or “orthostatic shock while suspended”) is the natural physiological response to the human body being held motionless in a vertical position for a period of time, resulting in presyncopal symptoms or loss of consciousness. It has been described in experiments of personal fall protection, and has been implicated in causes of death in mountaineering accidents, but it seems neither to be widely known about nor to have been presented to the medical profession. That should be plenty to start googling with. I won't try to summarize the condition other than provide one quote from that short 2007 paper: QuoteHealth professionals are all aware of the phenomenon of orthostatic intolerance.The example of the soldier standing motionless on parade (or the medical student standing and observing in theatre for a prolonged period!) who suddenly faints is not uncommon. [...] In a patient in vertical position, venous pooling occurs in the leg vessels due to gravity, which can lead to a 20% loss of circulating volume and a relative hypovolaemia. If the individual is then also immobile, there will be no muscle pump to provide venous return, with a reduction in cerebral perfusion leading to cerebral hypoxia. [...] However, if the patient is a climber hanging in a vertical position supported by a safety harness, is no longer using the muscle pump in the legs to climb and is unable to adopt a horizontal position, the individual will be unable to restore venous return to the brain. Reasons for the individual to pause motionless on a rope include exhaustion, hypoglycaemia, hypothermia, injuries, technical problems or mental problems such as fear. In addition, it is hypothesised that compression of the femoral veins by harness groin straps will contribute to a further reduction in venous return. Doug didn't report any factors making him really susceptible to blacking out. So here's another try at finding some possible explanation, tenuous or not, linking his experience to the hanging harness issue: @ Doug Davis: When you were waiting for the 2nd pass, leaning out the door etc, were you standing bent over and moving about, or perhaps crouched? A tight crouch at the doorway might put unexpected pressure on the legs from leg straps, doing that vein compression thing? Then you suddenly jump up (& out) and soon go woozy, like some people get when standing up quickly from being very relaxed lying down. Just an idea. Edited to add: I have since read NWFlyer's link to her thread from some years ago. A couple people did report anecdotally that they got woozy, if they had been crouched uncomfortably in the airplane for some time, and then suddenly allowed the blood to flow freely again by jumping out. So crouching with a harness on can seriously restricts blood flow, although I'm not sure of the exact mechanism causing someone to go woozy after. Quote Share this post Link to post Share on other sites
DrDom 0 #11 February 25, 2014 Good find. It escaped me the lack of venous return from the lower extremities not moving... it would have a similar effect to compressing the femoral veins as well! Cuts the venous return and preload... This totally makes sense though and if that is the ONLY reason for the syncope then the user could probably pump the legs a bit under canopy and improve return. Compressive stockings could also help but it would just decrease the venous capacitance... Staying well hydrated will also help since it increases volume.You are not the contents of your wallet. Quote Share this post Link to post Share on other sites
Doug_Davis 0 #12 February 25, 2014 pchapman @ Doug Davis: When you were waiting for the 2nd pass, leaning out the door etc, were you standing bent over and moving about, or perhaps crouched? A tight crouch at the doorway might put unexpected pressure on the legs from leg straps, doing that vein compression thing? Then you suddenly jump up (& out) and soon go woozy, like some people get when standing up quickly from being very relaxed lying down. Just an idea. It was an otter with a low door so I was crouched. Thats definitely one possibility but Iver never had that "standing up" feeling of faintness induce such a feeling, especially not nausea. I have experienced the symptoms you quoted above, especially having been in the army and having to have stood in change of command or award ceremonies for an hour or more. This was much more intense. Of course Im also much older that I was then. Good find though! Quote Share this post Link to post Share on other sites
pchapman 261 #13 February 25, 2014 I hadn't checked the thread before adding something to my previous post -- the "Edited to add" paragraph about those who went faint from crouching -- so the addition hadn't been posted by the time you replied. I think the problem with crouching can happen to people whether or not they are the type to go a little faint from time to time. The anecdotal evidence from a couple other people who went faint after crouching for a while before exit, at least shows that it is something that has happened before and is not just a theoretical concern. Quote Share this post Link to post Share on other sites
GooniesKid 0 #14 February 25, 2014 jimmytavino is there any chance, that within the hour prior to the jump, you may have had an "energy drink", or Two??? those can hit, all at once and give symptoms like you described.. glad you were Ok. Because i sometimes work double shifts and make it to a DZ in the wee morning hours, i find myself drinking at least 2 cans of Red Bull to keep me awake. I have found that for me there's a surge of energy but at the end of the day I end up napping in the packing area. One time i literally woke up @night after the DZ closed...weird how no one woke me up as a courtesy I have not blacked out under canopy but have experienced some of OPs ailments..whether the Red Bull is the cause i do not know..i'm not a doctor Quote Share this post Link to post Share on other sites
riggerrob 558 #15 February 25, 2014 I have seen this problem with students many times. It caused by adrenaline rapidly burning through reserves of blood sugar. After students have burned through all their reserves of blood sugar, they faint. Back in the static-line days, we didn't understand it, just knew that one student per thousand was unresponsive under canopy and we had to pick them out of the trees. We only started to understand the problem after doing tandems for a decade or two. The problem is a complex interaction between adrenaline and blood sugar. Adrenaline rapidly burns through blood sugar, then they crash. After all the excitement of a static-line jump, they relaxed under canopy and relaxed so far that they fainted. We only started to understand this problem after we noticed tandem students passing out under canopy. Hypoxia, insomnia, poor nutrition and dehydration all exacerbate the problem. 1 Quote Share this post Link to post Share on other sites
jumpwally 0 #16 February 27, 2014 Now that my friends,, is an answer..... smile, be nice, enjoy life FB # - 1083 Quote Share this post Link to post Share on other sites
Ralee26 0 #17 February 27, 2014 Vagal Nerve Fainting .... google it hutching over pinches the nerve in the abdomen and when you unrestrict the nerve out like a light Quote Share this post Link to post Share on other sites
dthames 0 #18 March 3, 2014 DrDomGood find. It escaped me the lack of venous return from the lower extremities not moving... it would have a similar effect to compressing the femoral veins as well! Cuts the venous return and preload... This totally makes sense though and if that is the ONLY reason for the syncope then the user could probably pump the legs a bit under canopy and improve return. Compressive stockings could also help but it would just decrease the venous capacitance... Staying well hydrated will also help since it increases volume. Interesting clip. Listen to what the guy says about his legs. https://www.facebook.com/photo.php?v=831011146926483 Instructor quote, “What's weird is that you're older than my dad!” Quote Share this post Link to post Share on other sites
