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Parachute use to prevent death, trauma when jumping from aircraft (2018) [pdf]

bmj.com

141–150 of 169 posts

Re: Parachute use to prevent death, trauma when jumping from aircraft (2018) [pdf]

#141
post #13

Earlier quoted context omitted.

They do a Randomized Controlled Trial on parachutes, but due to ethical reasons the plane is only a few feet off the ground and there's no effect (the parachutes don't have time to deploy).

Are you under the impression there would be an effect on trauma rates if the parachute managed to deploy during a 60cm jump?

No, but what I'm saying is if you watched the study the parachutes would look like they were doing nothing at all, not even flopping the chute out.

Re: Parachute use to prevent death, trauma when jumping from aircraft (2018) [pdf]

#142
post #92

Earlier quoted context omitted.

Makes me wonder if a bunch of the world's smallest flightless mammal (a fraction of the house mouse's mass) were released at altitude, would they survive? (Not proposing that this be done but thought experiments and/or simulations): https://en.m.wikipedia.org/wiki/Etruscan_shrew

“As god is my witness I thought turkeys could fly” https://m.youtube.com/watch?v=lf3mgmEdfwg

Thanks for that. I was a bit too young to appreciate WKRP when I would see it in syndication. Great line.

Re: Parachute use to prevent death, trauma when jumping from aircraft (2018) [pdf]

#144

I think people misunderstand what evidence based medicine is[0]. There are many types of evidence ranging from lab studies and expert opinion at the bottom to systematic reviews/meta-analyses at the top. The point being that we should strive for RCTs when possible , and that RCTs carry more weight than expert opinion or case-control. Many (I don’t have an exact number) clinical practice guidelines are based on expert…

(Saved you a search: Randomized Controlled Trial)

(Corrected)

Re: Parachute use to prevent death, trauma when jumping from aircraft (2018) [pdf]

#145

I think people misunderstand what evidence based medicine is[0]. There are many types of evidence ranging from lab studies and expert opinion at the bottom to systematic reviews/meta-analyses at the top. The point being that we should strive for RCTs when possible , and that RCTs carry more weight than expert opinion or case-control. Many (I don’t have an exact number) clinical practice guidelines are based on expert…

> Many (I don’t have an exact number) clinical practice guidelines are based on expert opinion or observational studies, and are completely valid/evidence-based (it’s just weak evidence).

A big problem is that humans have a preference for action, and a dislike of waiting for information.

Many flawed guidelines are based on a desire to act even in the absence of evidence of benefit.

"Primum non nocere" is probably the most accepted but least respected tenant of good medical practice.

Re: Parachute use to prevent death, trauma when jumping from aircraft (2018) [pdf]

#146

I think people misunderstand what evidence based medicine is[0]. There are many types of evidence ranging from lab studies and expert opinion at the bottom to systematic reviews/meta-analyses at the top. The point being that we should strive for RCTs when possible , and that RCTs carry more weight than expert opinion or case-control. Many (I don’t have an exact number) clinical practice guidelines are based on expert…

(Saved you a search: Randomized Controlled Trial) (Corrected)

Randomised controlled trial.

Controlled means there is a control arm that get no treatment, or treatment as usual (depending on what's needed).

Ideally a Db-rct a doubly blinded randomised controlled trial.

Re: Parachute use to prevent death, trauma when jumping from aircraft (2018) [pdf]

#147

I think people misunderstand what evidence based medicine is[0]. There are many types of evidence ranging from lab studies and expert opinion at the bottom to systematic reviews/meta-analyses at the top. The point being that we should strive for RCTs when possible , and that RCTs carry more weight than expert opinion or case-control. Many (I don’t have an exact number) clinical practice guidelines are based on expert…

(Saved you a search: Randomized Controlled Trial) (Corrected)

Apologies, bad medicine habit to use ambiguous acronyms.

I meant "randomized controlled trial" in this case (as the post). "Randomized clinical trial" is often used interchangeably but does not necessarily require a control group (e.g. a non-inferiority study comparing two different treatments).

Re: Parachute use to prevent death, trauma when jumping from aircraft (2018) [pdf]

#148

Earlier quoted context omitted.

At altitude it's very cold, the shrews don't work well in the cold due to the same thing that makes them suitable for this experiment - they are very small, thus they lose heat to the environment easily. So, it's possible they freeze to death first. But yes, I imagine that if they survive the cold and aren't falling onto a hard surface (e.g. they land in grass, not a car park) they would survive. For them other than…

Research is obviously warranted on the possibility of shrew blankets that can automatically detach when they touch down.

Nah, do the same thing they did for one of the Venus landers--fasten them with something that melts. Once they have reached an altitude where the temperature won't kill them the tether melts and the blanket falls away. (On Venus they did it to cut a chute because it would have made the lander fall so slowly it would have died before landing.)

However, shrew blankets change the whole scenario to irrelevance--a shrew in a blanket sufficient to keep it safe has very different aerodynamic behavior than a naked shrew.

Re: Parachute use to prevent death, trauma when jumping from aircraft (2018) [pdf]

#149

I came to leave a snarky joke comment about "in mice?", and then I remembered that mice don't actually need parachutes because their terminal velocity is roughly the same as a human using a parachute [1]. If someone actually ran the study with mice, they'd find that parachutes aren't necessary! 1: https://johnmjennings.com/can-a-mouse-survive-a-fall-from-a-...

The fact that mice don't appear to deliberately jump off high things as a way to get down tells me that they probably do get hurt... Just because they don't fall super fast doesn't mean they don't get injured because they don't have as much distance to "drop and roll" like a human does.

Note that mouse survival depends on the landing. It's quite reasonable for a mouse to fear heights even if in the *typical* situation it won't be hurt. If a mouse freely jumped down and was impaled 1 time in 1,000 that would be a very bad choice for the mouse. Also, a mouse who jumps down might find itself in a situation where it can't get home.

Re: Parachute use to prevent death, trauma when jumping from aircraft (2018) [pdf]

#150

Earlier quoted context omitted.

The fact that mice don't appear to deliberately jump off high things as a way to get down tells me that they probably do get hurt... Just because they don't fall super fast doesn't mean they don't get injured because they don't have as much distance to "drop and roll" like a human does.

> The fact that mice don't appear to deliberately jump off high things as a way to get down tells me that they probably do get hurt... It's not how this works, cats are decent swimmers yet they generally refuse to get anywhere close to water…

Cats live warm--what is a perfect thermal balance for them (where their body needs not expend any effort for heating or cooling) is unpleasantly warm for a human (who will be sweating.) Typical water will be chilling for a cat. Going swimming in most environments will pose a hypothermia risk at times and thus fearing it is a logical evolutionary result.
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