The CycleChat Helmet Debate Thread

[ufkacbln]

Was it not Brothers Gibb?.

Not any more.........

 

[srw]

Yes - my bad. I was using colloquial English, in which "heart attack" is used interchangeably with "cardiac arrest".

Pulling what you're saying apart:

"A whack to the head led to unconsciousness" - that's possible, although it's your assumption in this case.

"It was so severe that it led to "inevitable" cardiac arrest" - that's what I'm struggling with. I've searched reasonably diligently, and can't actually find any evidence of this being other than a remote possibility in the event of really serious head injury - of the sort that would crush a helmet, a skull and large chunks of brain. Certainly it seems far from "inevitable".

"When you are properly unconscious for any length of time you will need CPR" - I'm no medic, but I simply don't believe that. Coma patients don't need CPR as the heart can carry on beating long after the rest of the body's functions have given up the ghost.

"The cardiac arrest part is the inevitable consequence of a proper spark out" - that's the bit I'm inviting you to reconsider.

The whole hit head - cardiac arrest - CPR scenario seems far less likely than a very simple, and sadly all too common heart attack - cardiac arrest - CPR scenario. If you want to think about cardiac arrest arising from trauma, a trauma to the chest looks more likely to result in cardiac arrest than an equivalent trauma to the head.

Found something which appears to be quite interesting.
http://www.mayoclinicproceedings.org/article/S0025-6196(11)64254-7/fulltext#cesec10

Full disclaimer - I'm not a medic. I may be misinterpreting this. But it seems to say that head injury results in breathing stopping. And (based on a rat model) you need a really substantial blow to the head - one inducing a pressure of 3 atmospheres inside the skull - to stop breathing for long enough to cause cardiac arrest.

 

[deptfordmarmoset]

Went for a walk in Greenwich. Spotted this nice car..and a wrong way round plastic hat.

View attachment 138640

Watch out for that car's driver though. Nobberissimo at the wheel, more suited to an Audi.

 

[glasgowcyclist]

My MiL burnt my helmet!

Friction?

GC

 

[Racing roadkill]

Yes - my bad. I was using colloquial English, in which "heart attack" is used interchangeably with "cardiac arrest".

Pulling what you're saying apart:

"A whack to the head led to unconsciousness" - that's possible, although it's your assumption in this case.

"It was so severe that it led to "inevitable" cardiac arrest" - that's what I'm struggling with. I've searched reasonably diligently, and can't actually find any evidence of this being other than a remote possibility in the event of really serious head injury - of the sort that would crush a helmet, a skull and large chunks of brain. Certainly it seems far from "inevitable".

"When you are properly unconscious for any length of time you will need CPR" - I'm no medic, but I simply don't believe that. Coma patients don't need CPR as the heart can carry on beating long after the rest of the body's functions have given up the ghost.

"The cardiac arrest part is the inevitable consequence of a proper spark out" - that's the bit I'm inviting you to reconsider.

The whole hit head - cardiac arrest - CPR scenario seems far less likely than a very simple, and sadly all too common heart attack - cardiac arrest - CPR scenario. If you want to think about cardiac arrest arising from trauma, a trauma to the chest looks more likely to result in cardiac arrest than an equivalent trauma to the head.

You need to search more "diligently" even your "diligent searching" on head whacks causing heart attacks failed to turn up countless cases of people developing blood clots, as a consequence, which travel to the heart's blood vessels, and cause an actual heart attack, which may or may not ( but often does ) lead to cardiac arrest. Heart attacks don't always lead to cardiac arrests, if you spot the symptoms of the heart attack early enough, and act on it, the cardiac arrest can often be avoided. There's so much else wrong with what you typed, I would need about a week to address it all. I can't be bothered. I would suggest that you go and get some first aid qualifications, then come back, when you've got more of a clue. Even the basic 3 hour EFAW etc. course would do.

 

[Justinslow]

Had a conversation with one of my mothers friends yesterday, she was telling me about a club comrade of her son in law (still with me?) he apparently had a collision with a Deer. He wasn't wearing a helmet and has suffered quite severe head injuries. The general jist was that clearly a helmet would have helped him. I found myself explaining that helmets are quite thin and weak and in certain countries the incidence of head injuries hasn't dropped with the compulsive use of helmets, my mothers friend had to agree and was surprised.
A helmet may have helped him, who knows, I just felt I had to balance the argument. What's happening to me ?

I still "mostly" wear my own helmet by the way .

 

[ClichéGuevara]

Had a conversation with one of my mothers friends yesterday, she was telling me about a club comrade of her son in law (still with me?) he apparently had a collision with a Deer. He wasn't wearing a helmet and has suffered quite severe head injuries. The general jist was that clearly a helmet would have helped him. I found myself explaining that helmets are quite thin and weak and in certain countries the incidence of head injuries hasn't dropped with the compulsive use of helmets, my mothers friend had to agree and was surprised.
A helmet may have helped him, who knows, I just felt I had to balance the argument. What's happening to me ?

I still "mostly" wear my own helmet by the way .

Helmets and Hart attack theme building.

 

[Tanis8472]

Oh dear that's a belter lol.

 

[Wobblers]

It's more to do with the fact that the guys whack to the head caused him to get into such a state of unconsciousness, that the inevitable cardiac arrest ( not heart attack, they are different things), although a heart attack often leads to a cardiac arrest, occurred. When you are properly unconcious for any significant length of time, you will need CPR fairly quickly. The cardiac arrest part, is the inevitable consequence of a proper spark out.

You don't know much physiology, do you?

Firstly, for a brain injury to cause cardiac arrest, severe damage must be done to the brain stem. Damage severe enough to be highly likely to lead to death by itself. Secondly, the idea that unconsciousness inevitably leads to cradiac arrest is also untrue. Unconsciousness can lead to respiratory arrest through obstruction to the unguarded airway. This is why the very first thing taught on a first aid course is the recovery position and the importance of preserving the airway.

 

[Wobblers]

You need to search more "diligently" even your "diligent searching" on head whacks causing heart attacks failed to turn up countless cases of people developing blood clots, as a consequence, which travel to the heart's blood vessels, and cause an actual heart attack, which may or may not ( but often does ) lead to cardiac arrest. Heart attacks don't always lead to cardiac arrests, if you spot the symptoms of the heart attack early enough, and act on it, the cardiac arrest can often be avoided. There's so much else wrong with what you typed, I would need about a week to address it all. I can't be bothered. I would suggest that you go and get some first aid qualifications, then come back, when you've got more of a clue. Even the basic 3 hour EFAW etc. course would do.

This is just nonsense.

A heart attack is caused by a blockage in the arteries in the heart muscle, thereby depriving part of the muscle of blood flow. Injury is unlikely to generate clots that reach tthe systemic circulation. Clots may form afterwards through the enforced inactivity - this is deep vein thrombosis. And clots that do form won't reach the heart - they'll be caught in the capillary beds of the lungs, which is pulmonary emobolism. This in itself is a life threatening emergency which will not be helped by treating it as a heart attack. It also has nothing whatever to do with head injury.

I hope you're not planning on getting any medical qualifications.

 

[Wobblers]

Pat. there was nothing inside the helmets you dropped, this I feel makes the difference on how they absorb a blow.

Tough old lump of cheese is all I can say.

A helmet can only work by reducing the acceleration experienced in a collision. The only mechanism that this can occur is by it compressing. You are claiming that a helmet does not compress when struck with a hammer. A simple application of Newton's Laws of Motion mean the acceleration would therefore be passed to the wearer without reduction, therefore there can be protection if that's true.

For what it's worth, materials scientist is my day job.

Oh, and one more thing. You're right in that a helmet will behave differently when it's worn. Unsupported, it'll bend under an applied load, thereby distributing that load across a greater area. Supported, the skull beneath will prevent much of that bending. Any load will remain a point load. Ideally, you'd have a very stiff but ductile outer shell to distribute any impact loads across more ot the helmet (aluminium would probably make a reasonable job of it). Unfortunately, the polycarbonate that is actually used is far too brittle and lacks stiffness to be effective.

 

[slowmotion]

Here's something for all you Dr Kildares out there.....

http://ceaccp.oxfordjournals.org/content/12/2/67.full

 

[screenman]

A helmet can only work by reducing the acceleration experienced in a collision. The only mechanism that this can occur is by it compressing. You are claiming that a helmet does not compress when struck with a hammer. A simple application of Newton's Laws of Motion mean the acceleration would therefore be passed to the wearer without reduction, therefore there can be protection if that's true.

For what it's worth, materials scientist is my day job.

Oh, and one more thing. You're right in that a helmet will behave differently when it's worn. Unsupported, it'll bend under an applied load, thereby distributing that load across a greater area. Supported, the skull beneath will prevent much of that bending. Any load will remain a point load. Ideally, you'd have a very stiff but ductile outer shell to distribute any impact loads across more ot the helmet (aluminium would probably make a reasonable job of it). Unfortunately, the polycarbonate that is actually used is far too brittle and lacks stiffness to be effective.

Did I say that?

 

[ufkacbln]

Ironically any head injury that results in the level of damage that suppresses breathing is not going to be the only one.

In an injury that delivers that level of impact then there will be other injuries to the chest, abdomen and limbs

These will also produce mechanisms to suppress breathing and cause cardiac problems.

The other mechanism pointed out by the Dental Associations is that the helmet design at present fails to protect the face and facial injury with the possibility of swallowing blood, or teeth can be a cause of obstruction, causing cessation of breathing

So really we should be looking at full face helmets and assessing body armour

 

[ufkacbln]

Friction?

GC

Tidied up and being visually impaired placed it on a ceramic hob that was being used to cook supper