Near miss in Imlay

[spinesnaper]

OK perhaps that is a bit dramatic.

However, I did have an issue with the second to the last rap. It is about 40 feet and free hanging. About half way down, I felt like was going to black out. I was carrying my pack which contained the water soaked 200 foot 8.3mm rope. My harness is a Petzl Corax. But this is precisely the same harness I have previously used. I simply replaced it due to wear. Adding to top heaviness over the past couple of years I have been doing a lot of work on my shoulder muscles to help a shoulder impingement. My chest size has gone from 39 to 42 so I am more top heavy than I have been in the past.

I felt top heavy and was straining to stay upright which seemed to be causing the sensation of blacking out. Feeling that I was at risk of loosing control, I called out for a fireman's belay. This allowed me to pull it together and get down. I changed things up for the last rap. I took off my pack and clipped it to my cows tail. I took a double length runner and made a figure of 8 which I put my arms through and clipped to the rope above my rap device (ATS). I started off nervous and at first tried to stay up right-not comfortable. Then I leaned back and stabilized at about 45 degrees from horizontal and could relax into this taking all the pressure off the diaphragm. From there I lowered away, easy.

I would appreciate any insight on these issues. This experience has given me an entirely new insight on rappel accidents. I am now convinced that suspension trauma can occur just from rappelling and loss of consciousness from suspension trauma during a rap could account for some accidents where a canyoneer appears to loose control in the middle of a rappel and then falls to the ground uncontrolled.

[2065toyota]

I clip a single biner to my upper left shoulder strap and after a big free starts starts will clip that biner to the the rope above the device. Then you just kick back and relax. It also adds one more small friction point

[ratagonia]

Suggestions:

Turn sideways. Honestly, your body is stronger when turned 90 degrees, rather than "flat".

For a canyon with a maximum rap length of 120 feet, don't bring a 200 foot rope.

Put your rope in a ropebag with flotation, then you can just chuck it down the drop into the pool. Make sure it has enough flotation for the rope you have in it.

Tom

[spinesnaper]

Suggestions:

For a canyon with a maximum rap length of 120 feet, don't bring a 200 foot rope.

Tom

Hmm, I think some of us have larger rope remudas than others. I did have the 200 in the dry bag. I can't tell you precisely why I decided to carry it out of the dry bag-thin oxygen in the parking lot perhaps.

While the body is stronger 90 degrees ( I assume you mean sitting up right) what I am saying is that I was having a problem sitting upright. I am looking to see if anyone has any experience with what I am talking about. I have not previously experienced an issue like this. Since rappel is perhaps the highest risk activity in canyoneering, I think it is worth talking about these types of problems.

Ken

[hank moon]

[QUOTE=spinesnaper] While the body is stronger 90 degrees ( I assume you mean sitting up right) what I am saying is that I was having a problem sitting upright. I am looking to see if anyone has any experience with what I am talking about. I have not previously experienced an issue like this. Since rappel is perhaps the highest risk activity in canyoneering, I think it is worth talking about these types of problems.


Half way down I felt I was getting suspension shock and at risk of passing out. I yelled for a fireman

[spinesnaper]

Briefly,

Suspension trauma only occurs when one is already unconscious / immobile, so I don't think it is relevant here. Judging from your post in another thread (2nd paragraph of quote, above), I think your faintness was probably related to nutrition (hydration, electrolyte + blood sugar levels. Did you grab a good bite to eat with some water + electrolytes before completing the last rappel?

I think Tom was saying that if you turned a bit sideways to the wall (instead of facing it), the greater lateral rigidity of the skeleton would have helped alleviate the muscle strain (hope that makes sense - I'm not a doctor). I recently had a struggle staying upright on a rap and stopped mid-rap to transfer the pack from my back to hanging from the rap device 'biner. Saved my aching abs and made the remainder of the rap a lot more pleasant.

Glad you weren't going down first, Ken! Great TR and congratulations on completing Imlay.

Hank

Thanks for your kind comments.

Just for reference, I am a surgeon. Suspension trauma is actually poorly understood. What we do know is that the harness affects the circulation from the legs causing a lack of blood flow to the brain producing a black out or lack of consciousness. The suspension causes the black out. In almost every other circumstance, a passed out human being would not stay up right. In the suspension situation, this does not mechanically occur and it is thought that this has some bearing on eventual death presumably by cerebral ischemia.

This is the first time I have ever experienced anything like this. I don't think it was related to my state of hydration or nutrition. Think back to all those videos we have seen where the rappeller is making smooth progress down and then suddenly seems to slip out of control and fall from the rappel.

I am suggesting that suspension trauma is the cause of many of these accidents. If we could reliably determine the root causes of these types of accidents, we could advise individuals as to what steps to always take to avoid these types of situations. It might be to remove upper torso weight ( i.e. hang your pack), have a chest loop to distribute the upper torso weight, etc.

I am curious to see if others have experienced this feeling as well.

Ken

[ratagonia]

I think Tom was saying that if you turned a bit sideways to the wall (instead of facing it), the greater lateral rigidity of the skeleton would have helped alleviate the muscle strain (hope that makes sense - I'm not a doctor).

Yeah. I lack a good set of words to describe what I am trying to say. Only a surgeon would know the technical terms...

Actually, maybe a surgical comparison would do. A Normal surgical position would be face up or face down. What I am saying is, your body is stronger, your ABS are stronger, when your body is facing face-sideways, rather than in the classic sitting position. I have found rotating my hips so one hip is down relieves the strain on my rather weak abs.

On that rap, my great thanks to Hank for calling up to me to hang... your... pack... when he realized this was a good idea. Communication was difficult with a lot of wind, so I greatly appreciate the thought, time and effort required to make that communication.

Tom

[ratagonia]

Hank

Thanks for your kind comments.

Just for reference, I am a surgeon. Suspension trauma is actually poorly understood. What we do know is that the harness affects the circulation from the legs causing a lack of blood flow to the brain producing a black out or lack of consciousness. The suspension causes the black out. In almost every other circumstance, a passed out human being would not stay up right. In the suspension situation, this does not mechanically occur and it is thought that this has some bearing on eventual death presumably by cerebral ischemia.

This is the first time I have ever experienced anything like this. I don't think it was related to my state of hydration or nutrition. Think back to all those videos we have seen where the rappeller is making smooth progress down and then suddenly seems to slip out of control and fall from the rappel.

I am suggesting that suspension trauma is the cause of many of these accidents. If we could reliably determine the root causes of these types of accidents, we could advise individuals as to what steps to always take to avoid these types of situations. It might be to remove upper torso weight ( i.e. hang your pack), have a chest loop to distribute the upper torso weight, etc.

I am curious to see if others have experienced this feeling as well.

Ken

How about this theory?????:

Late in the day, low on food, blood pressure down quite a bit. Clenching your abs for quite some time results in a further decrease in blood pressure ==> faintness.

Yeah, there is probably a fair amount of blood sequestered down in the legs at the same time, since those muscles are still. I would think suspension trauma partly comes about because the leg muscles (and arterial/venous/capillary muscles) relax and therefore the blood volume in the legs increases, and MORE blood ends up sequestered in the legs, since return flow is blocked. Seems like this would not happen in a few minutes.

Tom

[spinesnaper]

Tom

I am putting it out there and asking questions. You have studied more accident reports than most of us. Dehydration a contributing factor is certainly plausible. Just don't ask me to go back in there and give myself an IV bolus of fluids before starting down next time (but I am sure it would make me have felt a lot better). It is worth noting that suspension trauma can induce unconsciousness and remaining up right is thought to contribute to death. Interesting subject and I wonder if it contributes to more rappelling accidents than we realize.

Ken

[Aj84737]

I'm not a doctor. But I stayed at a holiday inn express last night.

[spinesnaper]

I'm not a doctor. But I stayed at a holiday inn express last night.


Oh, this big needle. Trust me... this isn't going to hurt a bit.

[nonot]

Sounds like your body was working overtime. I've almost passed out while swimming 100 yards at the end of a canyon, floating on my back. Sometimes, if your nutrition worked out that day how it did and you were working hard during the day, at the end, the body sometimes wants to shut down at an inconvenient time. I could see the ab workout at the end of a long day in Imlay triggering this. It may not be related to the harness at all.

[spinesnaper]

No this seemed mechanical related to the harness and being squeezed. Harness fit does seem to be a factor in suspension trauma and as Tom points out, one can't dismiss what happens when the tank is not full.

[2065toyota]

Gotta remember to breath also which is hard to do under stress sometimes

[ilipichicuma]

A similar thing happened to me when I was rappelling the big waterfall at Stewart Falls. It was a pretty long rap and I had a soaked 200 foot rope in my backpack. I had a hard time staying upright and started to feel faint. However, as I have since done several longer raps, I attribute this to the heaviness of the backpack. I really don't think my harness had anything to do with it. If I had had the sense to hang my pack there I'm sure I would have been fine.

[Iceaxe]

FWIW- I have a rather large friend I do canyons with occasionally. He often clips a quick draw to the haul loop on his backpack and to the rope near his head. This creates what he calls a lazyboy chair as he rests while leaning back against his pack on long free hanging rappals.

Tap'n on my Galaxy G3

[oldno7]

Spine
Is your harness compressing any arteries? Shoulder strap on pack? Did something fit different than before? New pressure point?
I was always of the belief that suspension trauma took more time than what is usually encountered on a rappel.
Sounds like lack of blood flow to me. And I did take first aid once(to qualify my opinion):mrgreen:

[Bootboy]

Your harness around the small of your back won't necessarily occlude any major arteries. The dizzy-near-passing-out sensation likely comes from the compression of a nerve of the lumbar plexus. Not that you should try it, but if you lean back in a chair that hits you right about the level of your shoulder blades, after a minute or two you'll get the sensation of falling over backwards and blacking out. It's kind if scary. The same thing can realistically happen anywhere along the length of your spine , and your harness can certainly exert enough pressure in the sweet spot.

It could also be a matter of blood flow but that would be caused by the leg loops on your harness. They would restrict return flow from your legs which, if it happens quickly doesn't allow your body time to compensate. Thus a rapid drop in blood pressure could cause you to black out.

[spinesnaper]

Your harness around the small of your back won't necessarily occlude any major arteries. The dizzy-near-passing-out sensation likely comes from the compression of a nerve of the lumbar plexus. Not that you should try it, but if you lean back in a chair that hits you right about the level of your shoulder blades, after a minute or two you'll get the sensation of falling over backwards and blacking out. It's kind if scary. The same thing can realistically happen anywhere along the length of your spine , and your harness can certainly exert enough pressure in the sweet spot.

It could also be a matter of blood flow but that would be caused by the leg loops on your harness. They would restrict return flow from your legs which, if it happens quickly doesn't allow your body time to compensate. Thus a rapid drop in blood pressure could cause you to black out.

Ouch. OK Bootboy. I seriously hope you are not a chiropractor because I am about to hurt your feelings. The dizzy-near passing out sensation is not caused from "compression of a nerve of the lumbar plexus." I know they did not teach you that at your wilderness first responder course. Perhaps you have the lumbar plexus confused with the solar plexus. Pinched nerves cause shooting pain down the legs and can also be responsible for various types of sensory and motor nerve dysfunction. Perhaps some type of extreme ridiculopathy might cause one to faint but typically these syndromes are associated with shooting pain down the back of the legs, numbness, and various degrees of leg weakness. The precise distribution of these signs allows one to localize the level of the disc pathology. That has nothing to do with what I experienced.

I was blacking out because my harness was interfering with venous return to the heart. Tom is correct that dehydration might contribute to this state. Harness fit also has something to do with it. What I was experiencing represents some type of suspension trauma. Classically this is thought to occur after more than 9 minutes of harness suspension were the legs are immobile. Compression of the legs and torso interferes with venous return from the lower extremities. This impairs blood flow to the brain and can cause loss of consciousness. Prolonged suspension is associated with systemic shock and death.

The more of this literature I read the more clear that this is really a poorly understood entity. I was hoping by making this post to elicit information from SAR types who may have more direct knowledge of this entity. I am just thankful that my partner was available to give me a fireman's belay so I could get reorganized. Like it or not, I am telling you that this is probably the cause of more than a few rappelling accidents where the rappeller seems to just let go of their brake hands and fall uncontrolled down the rope. There are more than a few videos out there showing this.

And yes you are right that rapid drops in blood pressure do cause people to faint.

Ken

[ratagonia]

I am just thankful that my partner was available to give me a fireman's belay so I could get reorganized.

Perhaps it is a bit too obvious, but...

Could not you have stopped, tied off, got both hands free and got your excrement together without a fireman's belay? Kind of a basic rap skill to stop and tie off, yes?

Tom

[spinesnaper]

Perhaps it is a bit too obvious, but...

Could not you have stopped, tied off, got both hands free and got your excrement together without a fireman's belay? Kind of a basic rap skill to stop and tie off, yes?

Tom

Tom

I am telling you that I was having a problem. As it turned out the fireman's belay was at least psychologically helpful. I was in fact tied off at that point and was not going anywhere but I was trying to figure out why I was having the issue and what to do to comfortably and safely finish my rap. I did not really sort it out hanging there. I simply recovered enough that I could safely complete the remaining 20 feet of the rap. As you can see, others have experienced this type of suspension trauma. I think I was lucky here. I am certainly happy this did not occur on the last rap.

Ken

[Bootboy]

I'm not a chiropractor, and I never said anything about a WFR course.

You're right that it was likely an issue of blood flow, which I stated, but the instance I cited is also possible. Do a little homework and you'll learn that. You may be right that it wasn't a nerve of the lumbar plexus, but there are myriad nerves in the region of your back where your harness would make contact, the higher your harness rides, the greater the likelihood of this happening, though still less than a vascular issue.

[spinesnaper]

I'm not a chiropractor, and I never said anything about a WFR course.

You're right that it was likely an issue of blood flow, which I stated, but the instance I cited is also possible. Do a little homework and you'll learn that. You may be right that it wasn't a nerve of the lumbar plexus, but there are myriad nerves in the region of your back where your harness would make contact, the higher your harness rides, the greater the likelihood of this happening, though still less than a vascular issue.

Wait, are you sure you're not a chiropractor?

:facepalm1:I have done my homework. Trust me, I have done my homework. I didn't just stay at a Holiday Inn. I am actually an associate clinical professor at the David Geffen School of Medicine at UCLA. On this one I know what I am talking about. However, if you have an actual reference that supports your position, please share it with me so I can understand where you are coming from.

Ken

[ratagonia]

Picked the wrong guy to arm wrestle with, Bootboy. :haha:

Ken - I recently tried a harness (that sucked) and had kind of the same problem, though less so especially since it was only for the subway. The rise was way too high, so the waistbelt was too high and effected my ability to breath. Thankfully, the raps in the Subway are short enough you don't really have to.

I'm not saying your harness was this bad, but perhaps it was getting there, and applied too much pressure on the diaphram. a poorly fitting harness also can distribute the weight poorly. Sometimes just the extra slop from the harness getting wet plus wetsuit can make the harness fit poorly enough to produce some undesirable effects.

As part of the diagnosis, did you mention how the harness/you felt on the final rappel?

Tom

[jman]

Wait, are you sure you're not a chiropractor?

:facepalm1:I have done my homework. Trust me, I have done my homework. I didn't just stay at a Holiday Inn. I am actually an associate clinical professor at the David Geffen School of Medicine at UCLA. On this one I know what I am talking about. However, if you have an actual reference that supports your position, please share it with me so I can understand where you are coming from.

Ken


Our resident Doctor! :)

We did the free rappel in Pleiades once with my mother who is 64 and had a similar experience to what you had, she said.

She claims her backpack was high on her back and she rappels at like a 120degree angle and the weight from the backpack was pulling her down while she was trying to keep stay upright made her breathing difficult.

Sure it's not exactly the same but I have to ask perhaps the angle of how you were sitting in the rappel made a difference? I dunno, but that's what my mum said about her "scary rappel" when she couldn't breathe.

[Brian in SLC]

I am suggesting that suspension trauma is the cause of many of these accidents. If we could reliably determine the root causes of these types of accidents, we could advise individuals as to what steps to always take to avoid these types of situations. It might be to remove upper torso weight ( i.e. hang your pack), have a chest loop to distribute the upper torso weight, etc.

"Many"? My guess is not. There's gobs of survivors of rappelling accidents and I dimly recall not hearing any of them say they felt faint or like they were passing out as the cause of their loss of control.

Orthostatic hypotension...interesting deal. Scary. Every blue moon I stand quickly out of a chair and feel faint...

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2658225/

Dehydration a player more than likely, harness fit, maybe some other malady that might cause low blood pressure. Worth havin' your partners keep an eye on you.

You're not taking any diuretics or vasodilators? Are you anemic?

Scary business. Yeah, I'd be making sure my harness fit well and I'd hang my pack from it when rappelling.

[spinesnaper]

"Many"? My guess is not. There's gobs of survivors of rappelling accidents and I dimly recall not hearing any of them say they felt faint or like they were passing out as the cause of their loss of control.

Orthostatic hypotension...interesting deal. Scary. Every blue moon I stand quickly out of a chair and feel faint...

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2658225/

Dehydration a player more than likely, harness fit, maybe some other malady that might cause low blood pressure. Worth havin' your partners keep an eye on you.

You're not taking any diuretics or vasodilators? Are you anemic?

Scary business. Yeah, I'd be making sure my harness fit well and I'd hang my pack from it when rappelling.

No, this was suspension trauma i.e. interference with venous return due to harness compression. No diuretics or vasodilators. And no I am not anemic. Did great on the last rap due to hanging my pack and using a figure of 8 to take some of the chest weight.

And yes you did provide a reference on suspension trauma from 2007. There are of course many more papers on this subject that unfortunately does not seem to be part of the canyoneering curriculum and should be.

Ken

[hank moon]

No, this was suspension trauma i.e. interference with venous return due to harness compression.

I am still wondering about your judgment in this case. From what I can see with web-o-vision, you seem willing to gloss over other potential factors that probably played a significant role, such as dehydration, exhaustion, etc. And perhaps you are also predisposed to faint for some reason(s)?* Note that suspension trauma can be induced entirely through hanging motionless in a harness, without any additional contributing factors, such as you had. However, this takes considerable time - and motionlessness - which were not factors in your case.

I am as interested as you are (maybe...) in learning more about suspension trauma and sincerely thank you for sharing your frightening experience in Imlay. However, I do think you have rushed to judgment in this instance. So, I challenge you to remove your helmet and don the science hat. On your next trip to the PC pit toilet, you might while away the minutes with some fine imported HHS / ST literature:

http://www.hse.gov.uk/research/rrpdf/rr708.pdf


*I certainly am - once literally fell off the table while having blood drawn

hank

p.s. can/would you share links to some of the videos you mentioned earlier?

[spinesnaper]

Hank

That is actually a very good reference you posted.

Here study this video posted on Youtube. I think that many of use have already seen this but think about this accident in light of this discussion on suspension trauma:


http://www.youtube.com/watch?v=_RncnnVST-0

I was looking for other video but the ones I have found could be consistent with a "slip." Of course if you are on the verge of passing out, almost any video will look like a slip.

It is also worth emphasizing that our knowledge of suspension trauma is by no means complete. I do agree that dehydration would of course be a predisposing factor but then perhaps this is always the case.

Ken

[Bootboy]

I can't find a source but it was explained to me by an ER doctor friend of mine. I asked him about last night at work. I've likely interpolated some incorrect information. Forgive meHe explained to me that trauma, even relatively mild, to the muscles of the lumbar region, can result in vertigo. He mentioned something about propriocetors and their relationship to the cerebellum leading to this. He said its more common in car accidents and in conjunction with whiplash injuries but can also occur with compression of the muscles and nerves of the lumbar region. He thought that rappelling with a pack on, if your weight is shifted back so that you had enough pressure on that region from your harness, could be more than enough to cause the sensation of vertigo, even a near syncopal episode.

[Brian in SLC]

Here study this video posted on Youtube. I think that many of use have already seen this but think about this accident in light of this discussion on suspension trauma:

http://www.youtube.com/watch?v=_RncnnVST-0


Discussed here.

http://www.bogley.com/forum/showthread.php?35747-Zion-Rappel-Accident

Doesn't make me think of suspension trauma in the least...

[spinesnaper]

And there is the testimony of the participant:

"He and his buddy were getting ready for a 300-foot rappel in the park this past Tuesday. Schriever went first while his buddy videotaped him. Right away, though, both knew something was wrong.

"I lose control and stop midway because there was a knot in the rope. So that saved me from falling even further," Schriever explained while watching the video.

But once he untied the knot, he couldn't stop. Schriever fell more than 100 feet, banging hard against the rock wall before dropping to the rocks below.

"I remember the first hit on my head, and it wasn't until I watched the video that I realized I hit at least two more times on the way down," he said.

[COLOR=#000000]In that split second, all Schriever could think of was his wife, two daughters and his unborn son, who is due in just two weeks. "I was like,

[ratagonia]

But then it begs the question of why did he lose control in the first place?

The fact that this does not make you think of suspension trauma, does not mean that it plays no role in this accidents.

You're really stretching for it Ken.

The guy was an idiot, had NO idea what he was doing, and set his rappel device with practically no friction. It is a real stretch to look further than that.

Sure, he could have had a stroke, been abducted by aliens for one second and returned with paralysis of his brake hand, or hit a gravitational anomaly caused by a passing Black Hole - all these seem as likely to the idea that he had instantaneous compartment syndrome causing loss of blood pressure to his brain.

Jus' sayin'...

Tom

[hank moon]

Ken, it seems to me that this incident could lead to some interesting safety research. While I disagree with your assertion that it was "suspension trauma" (a phenomenon associated with prolonged, motionless suspension in a harness) per se, I think we can both agree that it bears further study and increased awareness in the vertical community.

What happened to you* (and perhaps several others) seems to have been related more to top-heaviness than to the harness. Do you have access to any test facilities in your area where this issue might be studied further? Any interest in that?

hank

* 6 rap abs? Recline of doom? La-Z-Boy rap?

p.s. My worst experience in this vein was rappelling down Tilted Well (165') in Run to the Mill Cave, TN. I was supporting a cave diving expedition and had an old-school steel SCUBA tank on my back. Hellish. Good thing I was young and still relatively fresh, energy-wise.

[joeb]

What was your breathing rate on the rap? Maybe a combination of dehydration, fatigue & hyperventilation caused the issue? During my time lifeguarding at the ocean the last thirty years we see a lot of rescues where fatigue, panic plus rapid breathing causes the victim to feel like they are going to "black-out" and some of course do. I am not saying you were panicky but you were definitely in a state of physical & mental fatigue (face it - you were going down Imlay for the first time) and my guess is that the imbalanced pack got you scared and the adrenaline/rapid breathing kicked into overdrive. Whether or not hyperventilation/etc caused the issue, who knows but it could be a possibility versus a harness restriction issue

[spinesnaper]

What was your breathing rate on the rap? Maybe a combination of dehydration, fatigue & hyperventilation caused the issue? During my time lifeguarding at the ocean the last thirty years we see a lot of rescues where fatigue, panic plus rapid breathing causes the victim to feel like they are going to "black-out" and some of course do. I am not saying you were panicky but you were definitely in a state of physical & mental fatigue (face it - you were going down Imlay for the first time) and my guess is that the imbalanced pack got you scared and the adrenaline/rapid breathing kicked into overdrive. Whether or not hyperventilation/etc caused the issue, who knows but it could be a possibility versus a harness restriction issue

Tom

I know they teach skepticism at MIT so you are doing your job.

Having now reread and reviewed what rappel accidents reports I can from such great sources as bogley and youtube, I agree that most do seem to be associated with the participant releasing their hand from the brake side of the rope thereby profoundly increasing the effects of gravity on the rappel system. The anomaly of why the hand is released in many cases seems to be a slip causing the rappellers body to be slammed against a rock wall were upon the hand releases and I think we are all aware of what happens next. So far so good.

On the other hand, I know what I experienced and felt the harness compression which I do think was related to being top heavy and I have already acknowledged that dehydration certainly could play a role. Generally I am not anxious rappelling and did not have a concern until into the free hanging portion of this rappel when I experienced compression from my harness, top heaviness and lightheadedness all at the same time. I did consider just zipping down the rope but I was concerned that I might not be in control so fought the sensation, locked off my ATS and called for a fireman's belay. That worked out for me.

I think one makes a serious mistake assuming that suspension trauma only occurs hanging motionless for an extended period of time although this is the classical description. As for access for facilities to further research this issue, I am weight training an advanced team of top heavy rats as we speak to model the effects-just kidding. No I don't have resources for this and considering people have actually died suspended in harness suspension rescue scenarios, I suspect that an institutional human subjects protection committee would likely be reluctant to actually approve such research without a lot of very expensive life/safety safeguards in place. I am actually surprised that there is not more information from military research on this subject.

However, if I experience this again, I certainly will up date this thread accordingly.

Ken

[Brian in SLC]

But then it begs the question of why did he lose control in the first place?

The fact that this does not make you think of suspension trauma, does not mean that it plays no role in this accidents.Ken

"Schriever admits he didn't use the right gear and rope and he didn't wrap his safety line enough times around his rope. He's hoping this video will show others who love to rappel that no matter how experienced you are, you should always be 100 percent careful -- you usually don't get two chances."

You used it as a possible example to support your position. I still don't see any indication that the cause was in any way related to anything other than inexperience. He never mentioned he felt faint. Ect.

I follow accidents in both climbing and canyoning fairly closely. I own around 20 years of ANAM data. You could look up ACC (Alpine Club of Canada) data too as they keep fairly extensive records on accidents. Its just not on my radar.

I challenge you to find a single accident in the canyoning world that has even a remote mention of suspension trauma as a potential cause. There's plenty of rappelling accidents every year. And, they get picked apart for cause by us Monday morning quarterbacks.

Have had a few friends who've lost control on rappels...never due to feeling faint as a cause. Mostly lack of proper management of friction.

Stay hydrated. Get a harness that fits. Remember to breath when on rappel. Get the weight off your back especially on long drops with free air. All good stuff.

[joeb]

"I suspect that an institutional human subjects protection committee would likely be reluctant to actually approve such research without a lot of very expensive life/safety safeguards in place" - This is why when I was doing my Master's research we used lawyers instead of rats. No public outcry and here in California there is no shortage of them.

[hank moon]

Stay hydrated. Get a harness that fits. Remember to breath when on rappel. Get the weight off your back especially on long drops with free air. All good stuff.

X2

and...doctors should be skeptical, too :)

[spinesnaper]

"I suspect that an institutional human subjects protection committee would likely be reluctant to actually approve such research without a lot of very expensive life/safety safeguards in place" - This is why when I was doing my Master's research we used lawyers instead of rats. No public outcry and here in California there is no shortage of them.

Sweet

I am skeptical. Just sharing an experience. Ignore it at your own peril.

By the way, here are some recent references:

http://www.wemjournal.org/article/S1080-6032(10)00320-0/fulltext



Hum Factors. (http://www.ncbi.nlm.nih.gov/pubmed/22768638#) 2012 Jun;54(3):346-57.
Impact of harness fit on suspension tolerance.
Hsiao H (http://www.ncbi.nlm.nih.gov/pubmed?term=Hsiao%20H%5BAuthor%5D&cauthor=true&cauthor_uid=22768638), Turner N (http://www.ncbi.nlm.nih.gov/pubmed?term=Turner%20N%5BAuthor%5D&cauthor=true&cauthor_uid=22768638), Whisler R (http://www.ncbi.nlm.nih.gov/pubmed?term=Whisler%20R%5BAuthor%5D&cauthor=true&cauthor_uid=22768638), Zwiener J (http://www.ncbi.nlm.nih.gov/pubmed?term=Zwiener%20J%5BAuthor%5D&cauthor=true&cauthor_uid=22768638).
SourceProtective Technology Branch, Division of Safety Research, National Institute for Occupational Safety and Health, 1095 Willowdale Rd., Morgantown, WV 26505, USA. hxh4@cdc.gov

AbstractOBJECTIVE:This study investigated the effect of body size and shape and harness fit on suspension tolerance time.
BACKGROUND:Fall victims may develop suspension trauma, a potentially fatal reduction of return blood flow from legs to the heart and brain, after a successfully arrested fall if they are not rescued quickly or the harness does not fit them well.
METHOD:For this study, 20 men and 17 women with construction experience were suspended from the dorsal D-ring of a full-body fall-arrest harness. Their suspension tolerance time, physical characteristics, and harness fit levels were assessed.
RESULTS:Body characteristics (i.e., weight, stature, upper- and lower-torso depths) were associated with decreased suspension tolerance time (r = -.36 - -.45, p < or = .03). In addition, harness fit affected suspension tolerance time; workers with a torso angle of suspension greater than 35 degrees, a thigh strap angle greater than 50 degrees, or a poorly fitting harness size had shorter suspension tolerance time (mean differences = 14, 11, and 9.8 min, respectively, p < or = .05).
CONCLUSION:Body size and harness fit were predictors of suspension tolerance time. Selecting well-fit harnesses and establishing a 9-min rescue plan are suggested to ensure that no more than 5% of workers would experience suspension trauma.
APPLICATIONS:The study provides a basis for harness designers, standards writers, and manufacturers to improve harness configurations and testing requirements for better worker protection against suspension trauma.

[WyoTucky]

From now on, when I'm bonking, I'm going to say "oh no, i'm getting suspension trauma!"

This isn't to say you weren't actually getting "suspension trauma"

I can't even spell doctore, so how would i know.

[spinesnaper]

I am updating this thread as promised. I did Imlay for a second time in August 2014. I posted this trip. This time for the next to the last rap in Imlay, I hung my pack and used a chest loop to help direct the rope. Also I purchased a smaller harness. Now I am using a Petzl Corax 1. I did not experience any issues this time. The last rap was on Sterling 9mm Canyon IV-smooth. One could get use to rappelling on 9 mm rope. Just thought you might like to know.

[harness man]

Great thread, Spinesnaper! :nod:
YES.
Harness "suspension trauma" can be a serious issue!
In our 'day job' Desi and I are the world's largest manufacturer of stunt harnesses.
We design and fabricate stunt and acrobatic harnesses for Cirque du Soleil and most action films world wide.
Suspension trauma can include several different 'traumas' (like restriction of breathing), but the biggest issue for acrobats and stunt performers hanging on wires is the restriction of blood flow to/from the legs.
The usual culprit is the squeezing of the femoral artery(s) by leg straps/loops.
This has led to incidents of performers passing out, sometimes requiring trips to the hospital.
There are several contributing factors including the weight and physical condition of the performer, the time they are suspended, whether they are moving or stationary (not moving is the worst), and of course the design of the harness (does it provide enough surface area, padding, etc to keep restriction of blood flow to a minimum).
Here is what I suggest:
1) go to a well stocked climbing store and try on and HANG in a Bunch of different harnesses. Small changes in the design might make a difference by keeping away from the leg arteries. If your legs go numb that is a BAD sign: the femoral nerve is right next to the main artery. Generally, the more surface area the harness provides, the better. (Less lbs per sq inch pressure). I would favor harnesses designed for BIG WALL climbing- they are intended for more 'hanging around'.
2) Get pressure off of the legs by hanging your pack, when practical. Using a jumper sling from your chest area to the rope may relieve abdominal strain but still increase pressure on the legs.
Tom's suggestion of rocking to the side is a good one and also used by performers on the wires- it rolls the leg arteries away from the 'down' leg strap and takes pressure off the 'up' leg.
3) In the stunt world, fatigue and dehydration seem to be an important factor.
4) Limit exposure. A safe, smooth rappel will speed things up. Tried a CRITR yet? :mrgreen: :mrgreen: :mrgreen:
Best, Todd

[spinesnaper]

Todd

Thank you for believing! I know what I felt and yes wearing a pack with a wet 200 ft rope did not help, dehydration, and a loose harness all contributed.

CRITR -get this thing stocked with Sports Chalet! Soon my current ATS is going to be worn through and CRITR will soon be on the harness. (Naturally, I would love to get a $250 titanium scarab). The reality is that these devices are disposable with very limited lives in wet canyons and fine sand abrading the soft aluminum surfaces.

I am looking forward to getting one of your packs! Please tickle your pack post when those babies are available for order.:2thumbs:

[harness man]

Hi Spinesnaper
Your experience was/is a common concern in the entertainment industry.
For aerialists and stunt people, harness suspension trauma is a serious hazard and is (supposed to be) carefully monitored by those who are supervising the performance.
Ignoring the symptoms (numb legs, pale skin, dizziness, feeling faint) could send you to the hospital as it did for Tom Cruise on a movie shoot a few years back when he passed out after extended time suspended in a stunt harness.
When consulting for flying effects companies, we count harness flight times in SECONDS (not minutes, or hours).
For canyoneering I am VERY picky about choosing a harness and go for comfort, support, and good fit above all else.
...back to the pack design...best, Todd