The Bends

[Orleander]

When were the bends discovered? I mean, we haven't been going down deep for all that long. When was it realized that if you came up slowly, you wouldn't die?

[Idle Mind]

Probably by looking at other organisms capable of great depths and observing their behaviour when surfacing? I'm not sure if sperm whales experience the same challenges we do, or if they have another mechanism of dealing with the problem.

[Orleander]

Probably by looking at other organisms capable of great depths and observing their behaviour when surfacing? I'm not sure if sperm whales experience the same challenges we do, or if they have another mechanism of dealing with the problem.

but why would they look at animals to see if they died when they came up? How would they make that connection unless they were in the water with the animal and saw it come up too quickly.
And I think whales do get the bends, they just tolerate it better than we do.

[Idle Mind]

Well, if we have a problem doing something, why not look at other organisms that do it and see how they perform such feats? I'm not really sure about the history behind deep sea exploration, I was just thinking aloud.

[spidergoat]

It first got widespread attention during the building of the Brooklyn Bridge, and was originally called caisson disease, a caisson being the structure designed to hold the water back at great depths. The workers who were down there for hours digging the foundations came up and got sick.

[cosmictraveler]

1670: Boyle demonstrated that a reduction in ambient pressure could lead to bubble formation in living tissue. This description of a viper in a vacuum was the first recorded description of decompression sickness.

1769: Giovanni Morgagni described the post mortem findings of air in cerebral circulation and surmised this was the cause of death.

1841: First documented case of decompression sickness, reported by a mining engineer who observed pain and muscle cramps among coal miners working in mine shafts air-pressurized to keep water out.

1870: Bauer published outcomes of 25 paralyzed caisson workers.
From 1870 to 1910 all prominent features were established. Explanations at the time included: cold or exhaustion causing reflex spinal cord damage; electricity cause by friction on compression; or organ congestion and vascular stasis caused by decompression.

1871: The St Louis Eads Bridge employed 352 compressed air workers including Dr. Alphonse Jaminet as the physician in charge. There were 30 seriously injured and 12 fatalities. Dr. Jaminet developed decompression sickness and his personal description was the first such recorded.

1872: The similarity between decompression sickness and iatrogenic air embolism as well as the relationship between inadequate decompression and decompression sickness was noted by Friedburg. He suggested that intravascular gas was released by rapid decompression and recommended: slow compression and decompression; four hour working shifts; limit to maximum depth 44.1 psig (4 ATA); using only healthy workers; and recompression treatment for severe cases.

http://en.wikipedia.org/wiki/Decompression_sickness

[Enmos]

Probably by looking at other organisms capable of great depths and observing their behaviour when surfacing? I'm not sure if sperm whales experience the same challenges we do, or if they have another mechanism of dealing with the problem.

They have another method of dealing with the problem. It's called evolution ;)

[Stryder]

There is actually a radiologically induced version of the Bends, it's when the lipids containing nitrogen are excited. Not a particularly pleasant feeling since it's like a sudden increase in Anxiety/Panic, especially for those that don't know where the panic attack has arisen from. Of course it's mild in comparison to compression.

[cosmictraveler]

lipids containing nitrogen are excited

Ohhhhhh, that sounds interesting, does it make one high as well? :shrug:

[Idle Mind]

They have another method of dealing with the problem. It's called evolution ;)
What mechanism did they evolve?

[synthesizer-patel]

but why would they look at animals to see if they died when they came up? How would they make that connection unless they were in the water with the animal and saw it come up too quickly.
And I think whales do get the bends, they just tolerate it better than we do.

I don't think whales have a particualr problem with decomression injuries as they dive with a single lungful of air - so only the nitrogen in that breath will dissolve into their bloodstream - just as human freedivers who dive to well over 100m and surface very fast don't have anything to worry about either.


That said over their lifespans - presumably due to such constant diving activity, there is some evidence of mild DCI damage, but as Enmos said - evolution has taken care of that so for them its nothing particularly life threatening

[cosmictraveler]

but why would they look at animals to see if they died when they came up? How would they make that connection unless they were in the water with the animal and saw it come up too quickly.
And I think whales do get the bends, they just tolerate it better than we do.


Two groups of whales, the Humpback Whale and the subspecies of Blue Whale found in the Indian Ocean, are known to produce the repetitious sounds at varying frequencies known as whale song. Marine biologist Philip Clapham describes the song as "probably the most complex in the animal kingdom".[7]

Male Humpback Whales perform these vocalizations only during the mating season, and so it is surmised the purpose of songs is to aid sexual selection. Whether the songs are a competitive behavior between males seeking the same mate, a means of defining territory or a "flirting" behavior from a male to a female is not known and the subject of on-going research. Males have been observed singing while simultaneously acting as an "escort" whale in the immediate vicinity of a female. Singing has also been recorded in competitive groups of whales that are composed of one female and multiple males.

Interest in whale song was aroused by researchers Roger Payne and Scott McVay after the songs were brought to their attention by a Bermudian named Frank Watlington who was working for the US government at the SOFAR station listening for Russian submarines with underwater hydrophones off the coast of the island.

The songs follow a distinct hierarchical structure. The base units of the song (sometimes loosely called the "notes") are single uninterrupted emissions of sound that last up to a few seconds. These sounds vary in frequency from 20 Hz to 10 kHz (the typical human range of hearing is 20 Hz to 20 kHz). The units may be frequency modulated (i.e., the pitch of the sound may go up, down, or stay the same during the note) or amplitude modulated (get louder or quieter). However the adjustment of bandwidth on a spectrogram representation of the song reveals the essentially pulsed nature of the FM sounds.


http://en.wikipedia.org/wiki/Whale_song

[Enmos]

What mechanism did they evolve?

I admit that I thought it was something else, but:

"Natural selection has in the large part solved the problem by developing dive behaviours that allow the animals to manage the problem," he said.

"Previous research does show that the animals display mid-water stops. At the time it wasn't apparent to anybody why they were stopping - but it fits with this hypothesis."
http://news.bbc.co.uk/2/hi/science/nature/4122119.stm


So apparently they can get the bends, but are using a similar method as we do to avoid it.


Although this article tells a different story (and agrees with what I thought):

"Modern whales of both branches have evolved exquisite adaptations to fight the bends. Some exhale before they dive to clear their lungs of nitrogen gas that could form bubbles, and many whales allow ample time between dives."

"When gas or fat bubbles form in the blood vessels that feed bone cells, the vessels can burst and seal off the oxygen supply to the cells, resulting in tiny lesions that can be detected by X-ray.

"It's a measure of small regular damage and not necessarily something traumatic," Beatty says.

None of the 331 modern whale vertebrae showed signs of decompression syndrome, while a handful of the thousand ancient whale bones contained such marks.

Beatty views the damage as flirtations with the deep ocean, before more modern whales overcame decompression syndrome.

But baleen and toothed whales may have evolved such changes independently. Signs of decompression were found only in very ancient specimens of toothed whales, while more recent baleen whale fossils showed damage, suggesting that baleen whales only evolved their defences much later."

"Some researchers have suggested that military sonar can startle whales into changing their diving behaviour, causing decompression syndrome."
http://www.newscientist.com/article/dn13862-early-whales-got-the-bends.html

I also remember something about them having a specialized form of hemoglobin or myoglobin.

[synthesizer-patel]

"When gas or fat bubbles form in the blood vessels that feed bone cells, the vessels can burst and seal off the oxygen supply to the cells, resulting in tiny lesions that can be detected by X-ray.



Interesting - that may explain why so many commercial / deep divers suffer from bone necrosis

[Orleander]

There is actually a radiologically induced version of the Bends, it's when the lipids containing nitrogen are excited. Not a particularly pleasant feeling since it's like a sudden increase in Anxiety/Panic, especially for those that don't know where the panic attack has arisen from. Of course it's mild in comparison to compression.

So it happens during x-rays???

[Orleander]

Do people who go deep in underground mines get the bends?

[Enmos]

Do people who go deep in underground mines get the bends?

Not really, or they would have to descent really far and come back up very very quickly.

[Orleander]

Not really, or they would have to descent really far and come back up very very quickly.

There are mines 2 miles deep. Is that how deep divers go? Don't they ride an elevator up? Elevators aren't that slow.

[Enmos]

There are mines 2 miles deep. Is that how deep divers go? Don't they ride an elevator up? Elevators aren't that slow.

For every ten meters that you dive the pressure increases with 1 atmosphere.

[Orleander]

For every ten meters that you dive the pressure increases with 1 atmosphere.

I have no idea what that means

[Idle Mind]

Most of the pressure you get from deep sea diving is due to the water. Depth into the Earth doesn't have you under water, so the pressure increase is going to be much more mild.

[Enmos]

I have no idea what that means

At sea level the pressure is 1 atm (atmosphere), you are carrying a column of air the height of the entire atmosphere (= 1.0332 kg per square centimeter).
As you know water weighs approximately 1 gram per cubic centimeter. So the pressure of a column of water on a square centimeter is a 100 grams per meter of the column. So a ten meter column (100 gram * 10 = 1 kg) exerts approximately the same pressure as the entire atmosphere does on a square centimeter.

[Roman]

There are mines 2 miles deep. Is that how deep divers go? Don't they ride an elevator up? Elevators aren't that slow.

The pressure increases by one atmosphere for every ten feet of water above you. As you can see, pressure increases rapidly as you descend in death. You need about 11km (11,000 meters) of earth air to equal 75% of an atmosphere. In other words, to have the pressure at sea level doubled by air, you need 22km of air above you. Going 4km down in a mine is only going to mean 15km of air is above you. With water, you need to only go 10 feet (3m) to double the pressure! To get that sort of pressure from air, you would need a mine that was as deep as one and a half Mount Everests. Typically, decompression stops are only made if you spend time below 40 feet, or 4x atmospheres. I think. It's been awhile since I've done PADI. 4x atmosphere would require something like 50km of mine shaft, which would put you well into the earth's mantle.

[Orleander]

Do you have to be a mammal to get the bends?

Is it possible that this may be a reason why whales beqach? Something chased them to the surface or Navy sonar bothered them?

[Idle Mind]

Yes, or an amphibious creature like a turtle. You have to breath "air", not collect oxygen from water via gills.

[Roman]

Yes, or an amphibious creature like a turtle. You have to breath "air", not collect oxygen from water via gills.

Nah.
You just need dissolved gases in your system to boil out when the pressure changes. PV = nRT, right? If nRT are all constant, and P goes down, then V must go up. Is that Boyle's Law?

Most fish have swim bladders, which expand and kill them. If you've ever pulled any deep sea fish up, you'll often find their guts protruding from their mouths. This is due to the swim bladder pushing their insides to the outside. Deep sea bycatch, thrown back either because no one wants it or because the government won't let you keep it (fish is too small, wrong species, etc), typically dies anyway because of this.

In fact, deep sea fish are extremely sensitive to changes in pressure, as going from 100 atm to 101 or 99 atm isn't as big a change as going from 2 atm to 1 atm or 2 atm.

[Idle Mind]

Well, I guess I assumed Orleander was talking about the Bends strictly -- not death due to massive internal hemmoraging due to the pressure change. And most creatures that live at depth tend to stay around that depth, correct? Only mammals really take a breath of air, then dive to several thousand feet before returning to the surface (or in the case of humans, construct equipment that allows us to breathe air while under water).

[Roman]

Isn't the Bends caused by a change in pressure resulting in dissolved gases turning back into gases?

Fish already have dissolved gases in them, and by lowering pressure, the gas comes out. Like opening a can of soda. Soda's made by putting water and CO2 under pressure, which means more CO2 gets dissolved. When you open the can, the pressure decreases, and bubbles form.

In mathematical terms:
P1V1=P2V2

So a fish at P1 = 100 atm with V1 = 1 (its body)brought up to P= 1 atm is going to have some problems with its V2.

[edit]
Doh. That's Boyle's law, which is wrong. It's Henry's Law:
p= k*c, where p = partial pressure of solute, c = concentration of solute, and k is a constant.

So p1 = k*c. At p1 = 100 atm, c1 = 1. If brought up to p2 = 1 atm, then c2 = 1/100. As the pressure decreases, the concentration of dissolved solute will come out as a gas.

[Fraggle Rocker]

Do people who go deep in underground mines get the bends?As someone else explained, there's no increase in pressure if you're going down into air; it has to be water. That's because water is much heavier than air.Yes, or an amphibious creature like a turtle.Turtles are not amphibians, they are aquatic reptiles like alligators and sea snakes. They have only lungs to breathe with. Amphibians such as frogs and salamanders have both lungs and gills.

[Idle Mind]

I didn't say they were amphibians, I said they were amphibious. I was using the generic definition of the word.

Adult amphibians don't have gills either, only the "larval" stages do.