Part 1 Horizon

'The situation up here as far as we know it,

'two have fallen, one of them fell about 1,000 metres

'and did not get up and is believed to be dead. Over.

'We originally had reports that two people fell 1,000 metres...

-'can you confirm, over?

-'Not sure, there could be.'

'But we simply don't know at the moment, over.'

In the most hostile environment on earth,

8,500 metres above sea level, a team of climbers are

about to embark on the final push to the top of the world.

Going to extreme altitude is like being a hundred years old.

You are breathless all the time - even at rest.

But this is no ordinary climbing team.

Oxygen saturation is 62 percent figure six-two, over.

They are doctors and they are here to rewrite our understanding of the human body.

Experimenting on themselves as they attempt to climb to the summit.

This is really pushing the boundaries of what is possible.

This team will turn Everest into the highest laboratory on Earth.

Why do it?

My answer to that would be to be part of one of the most exciting scientific experiments

that's existed in the last 20 or 30 years.

But nothing can prepare them for the life and death decisions they'll face.

In the last half-hour I've seen a complete disregard for human life.

With respect to your doctor... he will die.

The guys on the mountain who are continuing to go up in bad shape,

I wouldn't give them a cat's chance of living.

This is the story of an expedition unlike any Everest has seen before,

the story of a team of men and women willing to risk everything in the pursuit of knowledge.

I'm here to do a job and I want to get it done and go home.

I'm looking forward to getting home.

This is the story of Doctors in the Death Zone.

'Mike, this is Denny, over.'

'Mike, this is Denny, do you copy, over?'

It's the 24th of March, 2007.

A group of 60 doctors and scientists are flying to the Himalayas.

They're here to climb the world's highest mountain,

Mount Everest.

Lukla airport in northern Nepal is perched on a cliff 2,800m above sea level,

it is as far as mechanical transport can take them.

250 people will pass through this airport over the next three months.

They will form the Caudwell Xtreme Everest Expedition -

the largest research team ever to come to the Himalayas.

I don't like that at all.

-Not at all.

-I absolutely love it.

But from here it is a two-week trek to base camp.

Doctors Roger McMorrow and Nigel Hart have been climbing together

for 12 years but coming to Everest will fulfil a lifelong dream.

Everest is the undisputed highest mountain in the world.

It is probably the first mountain that I ever knew the name of. As a boy you hear stories about Everest

and climbing Everest and the adventures people have here.

It goes back to the first time you get into mountaineering.

The beauty of it, the isolation of it and also the physical challenge.

I can't say that I ever ever ever thought that

I could be contemplating trying to get to its summit.

But Everest is a killer.

For every 15 people that summit, one dies trying.

They are remembered in a memorial three days from base camp.

I've been to Everest twice before and on my first trip I ended up burying somebody up there.

Sundeep Dhillon is a military doctor and the only member of the team to have climbed on Everest before.

I think of all the people in the summit party I am probably

the most scared and wary of the challenges we're about to face.

14 of the world's highest mountains are in the Himalayas.

But the biggest challenge climbing them is nothing to do with technical ability.

Climbing high up on the mountain when there is so little oxygen is almost a dream-like state.

You feel like you're drunk, you feel sort of soporific.

Every footstep is an effort of will and physically pushing the body.

It's not uncommon to have to take 15...huge breaths like that

between each pace and despite that you just want to collapse down into the snow.

These doctors haven't come just to climb Everest...

..they're here to make a discovery.

They are hoping

to find something that will transform lives back home.

Many of the team are intensive care specialists

and they are risking their lives to save patients like this.

One in seven of us will be treated in intensive care...

..after a major accident,

traumatic surgery

or during an extreme illness.

But for intensive care consultant, Mike Grocott,

the fight to save a life almost always boils down to one thing.

What kills his patients is a lack of oxygen in their blood, or what doctors call hypoxia.

All the people that we see that are sick have hypoxia, in some form or another.

So they have low oxygen levels either because their heart

heart isn't working so well, isn't pumping the blood around the body,

their lungs aren't working so well that the oxygen isn't getting into the body.

And we see this all the time.

It's hard to think of a sick patient

who doesn't have problems with hypoxia.

And yet it's extraordinarily difficult to study them.

In intensive care survival often appears random,

some patients can endure extreme levels of hypoxia whilst others simply die.

It is a mystery that Mike Grocott and his team believe can only be

answered by putting their own bodies into an identical situation.

On Everest these doctors will become the guinea pigs.

They want to see how their bodies adapt to the lack of oxygen at extreme altitude.

We're taking a number of healthy, almost identical individuals

and then we are making them critically hypoxic for about three months.

How can they do it,

when our patients are dying with the same levels of oxygen in intensive care?

The further up the mountain they go,

the less oxygen they will have to breathe

and the closer they will push their bodies into intensive care.

It may be the things that predict how people do at high altitude will

be the same things that predict whether they'd survive a critical illness.

Just doing the research, without trying to climb

the highest mountain in the world, is a challenge in itself.

I'll be happy when we come back all in one piece.

If they can reach the summit they will have less oxygen in their blood than people who are critically ill.

A level of oxygen so low

they should be dead.

You see people breathe more, cardiac output, so the amount the heart pumps increases

so there's more oxygen pumped round the body

so the number of very small blood vessels increase as well.

So many people have died trying to get up to the summit.

The nervousness of impending disaster, it might not turn out OK.

You're gasping, as if someone's strangling you.

You go first, Mike.

Just go forwards.

Place it on there, then I'll go.

Right, two, three, lift.

This expedition started life five years ago and 4,500 miles away from Everest.

we had this idea of doing a research expedition to Everest.

About four years ago, we realised that really we either should

shut up and stop talking about it or get on and do it.

It was something that for at least a year and a half that we discussed in the pub over a pint

and weren't sure that it was translatable into reality.

I think that's, that's it.

We spent a lot of time sitting outside Parisian street cafes

discussing what we might do, and we started putting together

a group of people who were likely to be involved.

Me as the expedition leader...

and we kind of gathered the team as we went along.

They're all very experienced high altitude mountaineers.

This is a historical record of my least fit moment.

Mike's wife Dr Denny Levitt is one of the project's research leaders.

She's designed many of the experiments they'll carry out on Everest.

It'd would have been very difficult for him to have been

involved and me not involved because it's been very much a life-consuming project for the last year or so.

It's a challenge your husband being the boss because he's always right at work,

so we have a system where I'm always right at home, that makes up for it!

We're not fantastic climbers, we're not going to break any records

for climbing, but it's by a long way the largest high altitude research project

that's ever occurred, and I'm not sure that anything like this will be repeated for a very long time.

OK, go!

Right, to the end of the garden and back!

After two weeks of walking the trek is over.

Everest Base Camp is set on a glacier at the foot of the mountain.

At an altitude of over 5,000m this tent city is higher than any peak in the Alps.

-Brilliant job.

-Have a look around, see what you think.

What are you looking forward to?

-My bed.

-A cup of tea would be good.

And then my bed.

Now we're up near 5,000 metres, and we're starting to get that shortness of breath, the dry cough.

And so, the sense of what's ahead really is starting to build.

It's amazing to think really that at 5,000 metres we're just halfway up, and we're already finding it hard,

walking, and starting to think "Oh, my goodness, this is a very big mountain."

We've a long way to go.

Base Camp is so high there is 50 percent less oxygen than at sea level.

And this makes it a perfect natural laboratory to study the effects of hypoxia

or low oxygen.

We're here with a goal that we believe in

and that we think is valuable and at the same time have the opportunity to

live in this environment and potentially to climb to the summit and that is a unique opportunity.

I'm most looking forward to getting back to base camp, with everybody else absolutely fine,

and knowing that we've done what we came to achieve

without causing any harm to anyone.

Our priorities are very clear in terms of safety first, and then the science and then the summit.

It's amazing. It'll be a great place to live.

Over the next few months 213 people will be studied here

on this constantly moving world of ice and rock.

These tents house hundreds of thousands of pounds of advanced research equipment.

The doctors will conduct over 40 different experiments,

looking at every aspect of how the body copes with low oxygen.

They will measure every breath

and every heart beat.

The tests range from simply stepping on a box,

to biopsies that look at individual cells.

To look at cellular mechanism you need a bit of tissue

and the muscle is actually relatively easy to get to.

Easier than your brain, or heart or lungs.

Many of the results won't be known until they can analyse them back in the UK.

We have about 17,000 samples from the expedition as a whole.

The combination of these tests will create the most detailed picture

ever assembled of the human body at altitude.

We've got a lovely picture of all the tiny red blood cells

zooming through the small blood vessels, under his tongue.

Some of the experiments are so invasive

that they are only conducted on a small group of volunteers.

The one everyone is dreading is tonometry.

Behind me is the lab tent, and they're torturing people in there.

So this is lignocaine jelly.

It's a local anaesthetic jelly and it's a water-based jelly

so it will make the tube slide easily down through the back of Nigel's nose, into his throat.

Then he's got to swallow it down and it's got to go all the way down to sit in his stomach over there.

It wouldn't be in my top five things I want to do on this trip or any other trip.

But anyway, it's all for the good of science.

Belfast GP Nigel Hart has practised this test in London, he knows how unpleasant it can be.

I'm really not looking forward to this.

-Are you ready for this Nigel?

-Yes.

The experiment is designed to study one of the most common complications in intensive care.

NIGEL CHOKES

OK, swallow, chin forward, chin on your chest...

As the body becomes more and more hypoxic,

it attempts to protect the vital organs from the lack of oxygen by cutting the blood supply to the gut.

The gut is a relatively non-vital organ in the short term, so the body will draw oxygen away from that

to perfuse vital organs like the brain, the lungs.

This test will measure how Nigel's gut is reacting to the low levels

of oxygen on Everest.

This goes into one of the arteries in Nigel's wrist.

This sort of stuff people have to tolerate all day, every day

in hospital. It's quite a good, er,

learning opportunity for those of us who are on the other side.

Not that I'd want to do it too often.

Andre Vercueil is a liver specialist and well practised at performing this technique in intensive care.

There you go.

You can see that pulsing with each beat of Nigel's heart.

Ordinarily if we were doing this at sea level, the blood coming out

of here would be a bright orange red colour, but because there's less oxygen carried by the blood

it's this fetching blue colour.

But Dr Dan Martin knows that the low oxygen on Everest

is not enough to exactly mimic intensive care.

They need to push Nigel even further.

The other component we can simulate if you like is the increased oxygen consumption that sick patients have.

They require a lot more oxygen to get over the disease that they're suffering from.

And we can increase Nigel's oxygen consumption by getting him to exercise.

So although it wouldn't be quite right

to make him ill and study him, we can exercise him which increases the amount of oxygen demand on his body.

So we want to find the point at which

Nigel's gut becomes ischemic or lacks oxygen.

In critically ill patients it may do that to such an extent that the gut may die.

I think what you, what you sometimes forget is you're sitting here and it almost looks like

a laboratory, then you look outside the door and there's the ice fall.

It makes it all a bit difficult.

The studies at base camp are just the beginning of the team's work.

15 of the doctors are planning to take their experiments to the highest place on Earth.

It just looks like a maze...

..like a broken maze.

It looks really hard.

The first obstacle they face is the Khumbu Ice Fall.

Everest has so much history associated with it, so many books written about it,

and the Khumbu Ice Fall is one of the notorious obstacles,

that anyone who wants to climb Everest from this side has to get over.

It's basically a continuously moving river of ice

with the ever-present risk that part of it will fall down.

You can see those big blocks, some of them the size of houses

and they are coming down from time to time.

It has been impossible to ignore how unstable the mountain can be.

If a large serac or chunk of ice decides it's time to fall down

when one of our team is walking underneath,

there's very little you can do about that. The only thing you can do is minimise exposure by getting

people through as fast as possible and as few times as possible.

Behind the ice fall, and hidden behind the ridge of Nuptse,

is the Western Cwm, this broad, relatively flat valley that goes up towards the Lhotse Face.

As they climb to the summit the doctors will stay at Camp 2 for seven days.

The route meanders up to Camp 3 which is about halfway up and then across to the South Col.

Then up at the South Col we're into the area colloquially known as the Death Zone.

Above the South Col you can see the South East Ridge

heading up into the cloud and Everest summit.

And that's the other main area of risk for us because of the critical lack of oxygen.

Only at this extreme altitude, where there is one third of the oxygen

there is at sea level, can they find the answer to the mystery that brought them to Everest.

How does the human body survive with such low levels of oxygen?

As they begin their ascent the ice fall poses a challenge most of the climbers have never seen before.

The glacier is 450m deep and sliding down the mountain at over metre a day.

It is riddled with crevasses that can open and close without warning.

Sundeep is the climbing leader and the only person to have tackled the ladders before.

Everest is a very dangerous place.

If you asked me at this stage how many people would get to the top

I'd probably say somewhere between six to eight.

That's not really making an assessment on individuals...

-Nice work!

-Good job.

..that's just the toll the mountain takes on people and it would be

difficult to say who would or wouldn't be in the summit team.

It's quite a long way, isn't it?

If you fell here, you'd load these points here

far more than, than is probably safe for then.

You really, really don't want to fall here.

LABOURED BREATHING

-Hi, pixie.

-Hi.

-Three ladders is just here, it looks all right...

It is truly stunning though, isn't it?

Despite the danger, the ice fall is one of most extraordinary places on earth.

A vertical kilometre of shifting ice, breaking and cracking as it flows.

Every day in this jumbled world is unique.

Wow, it's hot.

It's kind of messy over to our left.

You can see where all these blocks come tumbling down.

This looks horrible.

It's tough-going, isn't it?

Woah, crazy.

Breathe, breathe.

To climb through the ice fall will be a gruelling experience for Mike and the team.

Let's go.

Not a place to pause.

What slows them down is not their fitness or strength but the lack of oxygen.

At this altitude, the thin air is so suffocating, they can never climb fast enough to exhaust their legs.

The body reacts by attempting to get more blood to the oxygen-starved muscles.

The lungs breathe harder, sucking in more air.

The blood is thicker with extra cells to carry oxygen.

And the heart beats faster.

But this traditional understanding of how the body copes isn't enough to explain one thing.

Why do some people,

no matter how fit, struggle to perform at high altitude?

Mike was an absolute star. As you can see, he's carrying

a lot of my gear, cos I was struggling a bit earlier on.

Particularly when we started cos it was really cold.

Ah, I don't think I'd had got up here if he hadn't helped.

But we're here in one piece at last which is excellent news.

I'll go and have a cup of tea.

Mike and the team believe what causes this difference is not how much oxygen is

pumped around the body, but how well the body uses that oxygen.

Understanding this is the major goal of the expedition.

Here at Camp 2 they will set up a new lab, repeating the tests they've done all the way from sea level.

But now the conditions are much tougher.

Here temperatures will drop to below minus-20

and then soar in the heat of the sun to over 40 degrees.

Living here will be more like camping in a desert than on a glacier.

And yet they are about to perform experiments that require all their skills as scientists.

Dan, you're going to feel a scratch.

At every stage of the climb the team will be taking a blood sample straight from an artery.

Measuring the level of oxygen in blood is a test Mike would do every day in intensive care.

-You all right there?

-Just about.

Arterial blood is the blood that is pumped out of the heart

having been through the lungs, so is the most oxygenated.

So it gives us a measure of how much oxygen the tissues are seeing.

At sea level a healthy person will have 10 to 14

units of oxygen in their blood, someone who is critically ill, around eight.

We've just analysed Dan's arterial gas sample and it, it's just astonishingly low.

I've never ever seen a sample, a content of oxygen in the blood as low in somebody who's still alive.

It's, er, 4.47 partial pressure of oxygen

in kilopascals which is a third of what it is at sea level.

I, I've just never seen, even on somebody on an intensive care unit,

critically ill with terrible lung damage, I've never seen a level this low, ever.

You should be worried.

Still alive.

It's a beautiful morning and this is my incredibly beautiful and historic temporary home.

Behind me here is Everest itself,

the highest mountain in the world and as you can see, it's cloudy

a little bit, it's windy and cold up there this morning.

So we're certainly not going anywhere today.

Over there is Lhotse...

another 8,000m peak which is the fourth highest mountain in the world.

And this tent here is, as far as we know, currently the highest laboratory in the world.

Until we put one up there next week.

Having established that all the team have levels of oxygen in their blood

that mean they should be dead, their next test

is designed to reveal why they are still alive.

To do this they have brought an exercise bike nearly 6,500m up the mountain.

That's perfect.

This is the most important experiment for the Xtreme Everest team.

It is the foundation of the whole expedition.

You've just got to go as hard and as long as you can.

The machine knows when you are fibbing.

By exercising on this bike Sundeep will push his body to the very limit.

It's a test he first performed in London three months ago.

It's one of our key hypotheses on the whole trip is whether actually

the way your cells use the oxygen changes when you're at altitude

when there is not much oxygen around.

They believe that Sundeep's muscles are using less oxygen up here

to do the same amount of exercise he did at sea level.

Really good, Sundeep.

Excellent. Doing really well, drive those legs.

What we think happens is that your cells basically tune up, a bit like a car engine.

So you can get more miles to the buck really, you can do more work for the same amount of oxygen.

And that would help explain why people with very low levels of oxygen in the blood

are still able to perform amazing feats like climbing Everest.

Denny thinks that Sundeep's cells have

adapted over the last few months and some how become more efficient.

They think that this happens in intensive care as well.

Some patients respond to treatment better than others

because their cells might be more efficient at using oxygen.

We can clearly see that some people have exactly the same number of red blood cells

and their heartbeat is the same and their breathing is the same.

But one performs far better than the other.

It's a revolutionary new theory.

If we could tune their cells into a more efficient state we may

be able to, in the future, improve their outcome in intensive care.

And that's why I'm here on Everest putting myself through this

so that I can hopefully improve their outcome in the future.

I think in our wildest dreams what we would love to see is that some people have certain genes

that allow them to use oxygen more efficiently than others.

So what we are really really hoping from this trip is

that we could target treatment to poor oxygen users.

It's quite a wild and big thing,

but we may go some stages towards identifying those mechanisms.

Really good, Denny. Keep pushing those legs round.

But to get the clearest picture of what is going on in their bodies they need to take

the exercise bike to the most extreme environment possible.

They will set up their final lab on the South Col.

The climbers will spend two days at 8,000m testing themselves to exhaustion.

If these experiments prove that their cells are more efficient

they may be able to develop a treatment that would save thousands of lives.

To get there they must first tackle the Lhotse Face.

This 1,000m sheer wall of ice towers above the Western Cwm.

It takes two days to climb the nearly vertical slopes with a constant threat of avalanche.

Yesterday we had an extraordinarily sad event.

We were in camp doing studies but the radio traffic gradually revealed that unfortunately one of the Sherpas

working with a different team had been hit by an ice avalanche

and as best we understand it had been killed instantly.

And that, that obviously upsets our Sherpas greatly and all the members of our group.

It's just a bit shocking at how easily a life can be snuffed out

in an environment where we're planning to walk exactly the same path in a few days' time.

And that's what I think is playing on all our minds.

I mean we're going on with our experiments this morning and you almost feel like saying "Oh,

"just close the door and you know I'll not bother this morning."

It's very difficult to justify any reason for putting yourself

at any extra risk, when you have a wife and two small children.

This morning's really focused our mind an awful lot on what we're doing here.

We came here to do a job, a lot of effort's been put into it

and, I want to do that job.

But at the same time, keen to get home.

The weather is changing high on Everest,

the threat of snow will make the mountain much more unstable.

With the science completed at Camp 2 Mike chooses to return to base camp

rather than continuing to climb with the increased risk of avalanche.

We came down on the advice of our Sherpas because there was

a warning of snow, which increases the avalanche risk.

It didn't snow, but while we were

walking through the Western Cwm there was a big serac collapse

which caused...

hundreds of tonnes of ice come rushing down the slope towards us.

Fortunately it stopped before it got to us but good thing to be down.

Living at high altitude has proved much harder than they had expected.

It's been a great week

but hard work. We've got everything we wanted to do scientifically done which is brilliant.

It's nice to be warm again and to be able to breathe again.

Virtually everything we did has not been done before.

A few things that have have not been done with the same degree of fidelity so we're delighted.

The appetite affects you quite a lot.

So you might notice we've all lost quite a lot more weight,

I think the record is 11kgs so far.

To climb Everest the team need to be as strong and healthy as possible, even a simple cold could stop them.

They will wait here at base camp trying to regain their strength

until the weather on the summit clears.

Entertainment is thin on the ground at base camp,

the climbers have had to find their own ways of keeping busy.

You can control it very well at home, at sea level but here it's not so easy! Steady...

This is the highest-flying model helicopter in the universe.

Do you know why he's in here? To get his hard drive to work.

We put it out here.

The disk drive is working!

-Is it working?

-Absolutely perfect.

Who did that? I bet that was Grocott.

WHISTLING SOUND

Are you ready? Let's go get them!

The climbers have been waiting for

the weather to clear on the summit for nearly three weeks.

It's pretty good in that humidity is pretty well zero,

precipitation is zero, right up to the 1st or 2nd June.

So, that's very good. The only thing we've got is the jet stream

and that is tracking from a north-westerly down to a south-easterly direction

so it's getting closer and closer towards Nepal.

Wind speed will be the thing that stops them. I don't think there'll be any snow for the next ten days

so it's just the wind.

It's 6am. 15 of the climbers are getting ready to leave Base Camp for the last time.

Five years of planning has brought them to this point.

They will have one chance to climb to the summit,

the smallest problem could mean abandoning their science for good.

I can't find my gloves!

Building ourselves up, it's all in the mind.

As intensive care specialists all the doctors are aware of the dangers they face climbing at altitude.

I think everybody's feeling pretty strong.

It looks like we've got between seven and ten days of good weather

without high winds.

Looking at the top of the mountain today, it looks really calm.

Fingers crossed that the weather holds and we can get up and get down safely.

I'm looking forward to bringing everyone back down in a week's time.

I'm quite excited, ready to go,

it's a big day today and a big week ahead of us.

I think for everyone it's a mixture of excitement and nervousness really to be honest.

-Terrified.

-Terrified.

-Did you bring the guide book?

-No, I left it in the tent.

'Graham, this is Mac, go ahead.'

What terrifies the climbers the most is not avalanches or frostbite...

Six to eight hours of misery coming up!

..it's the effects the low oxygen will have on their brains.

Protecting the brain is Mike's top priority in intensive care.

Without oxygen, cells die in minutes,

leaving a patient permanently brain-damaged or even dead. When the brain suffers a major trauma,

like in car accident, it swells and pushes against the inside of the skull.

As the pressure builds less oxygen gets to the brain causing a spiralling effect.

The same thing can happen on the mountain.

The low levels of oxygen are enough to trigger the same kind

of brain swelling. It's called High Altitude Cerebral Edema

or HACE.

It is the most serious effect of climbing at altitude

and nowhere on Earth is the threat greater than on the summit of Everest.

At nearly 30,000 feet, it's the cruising altitude of a jumbo jet.

If a climber were to be dropped straight onto the summit

their brain would shut down, stopping them breathing and they'd suffocate in minutes.

To counter these effects the Xtreme Everest climbers

have been training their bodies to cope with the low oxygen.

Over the last six weeks they've been climbing the mountain in stages,

with each trip they go a little higher.

But despite this cautious assent some of the team have found climbing beyond Camp 2 difficult.

First off my heart started going a terrible pace

and then I just started to feel very woozy.

Not so much woozy, but as though I was going to black out.

And, er, I thought "Wow, the altitude kicks in quickly."

I thought I was stuffed.

And I was breathing really fast.

Honestly everything was just going "Woo, black, black can't see, woo, I've gonna pass out here."

I was thinking "Shoot!"

YOU were thinking shoot!

Yeah, you were thinking "Darn, I've got to go down as well."

Nigel Hart is lucky.

The effects of the low oxygen have turned out to be mild.

But climbing at this extreme altitude is a game of Russian roulette.

The most important thing for us to understand is whether he'll be walking wounded or stretcher case.

I'd feel happier with Andre short-roping him all the way down.

For one of the team the worst has happened.

There should be about 30 cylinders up there, just keep on using it.

Did you give him 8mg?

Whilst climbing on the Lhotse Face anaesthetist Patrick Doyle has

become confused and disorientated, these are classic symptoms of HACE.

The bizarre thing is you know I feel 1,000 percent better and I think "Well, what's all the fuss about?"

You think, "I'm sure I could go back up there" but it's just...

How do you feel about not going back up?

Er...

a bit emotional not, not being able to do it but,

er, I always said I'm gonna be totally sensible and, er.

It's good to have you back down safe, Pat.

But we're all gutted for you as well.

I didn't think it would be me!

Staying at Camp 2 should allow Pat to recover but he can't climb any higher.

You look better than we could have hoped.

After two months of preparation, his summit dreams are over.

Pat was one of the strongest climbers and the effect

of the altitude on him has shocked the whole team.

He's sensible, he wouldn't have gone up if he was feeling super crook.

-It sounds very much like HACE.

-Yeah.

It's difficult to deal with in hospital even.

Caudwell Base Camp, this is Mike, over.

He's in the right place with the right people.

They all know that above 8,000m, the critically low levels of oxygen

mean they will run the risk of suffering permanent brain damage.

We've got at the moment an uncertain medical situation up here.

It's Pat and he's probably got a touch of cerebral edema.

He's hopefully going to get better pretty soon.

I'd have thought if he's well here, he'll want to stay here.

He's pretty sensible and wouldn't want to go back up.

With Pat ill Mike has to reorganise the team.

If they are to reach the summit they can't afford any more delays.

-Then at least you two are together.

-We can send the first group up

which would only delay us by a day.

We'll go and have a look at that weather again.

The team has split in two. Sundeep is leading an advanced party

to Camp 3. Mike and the main climbers will follow a day behind.

But getting to Camp 3 means climbing the Lhotse Face.

Doing this is a monotonous exercise.

Hour after hour of hauling yourself up a sheer wall of ice.

Clipping off and on ropes every few metres.

As the oxygen drops the effects on the brain become more profound.

Even the simplest of tasks becomes challenging.

The history of deaths on Everest

is littered with stories of terrible simple mistakes.

There are people who won't do up their harnesses properly,

there are people who when it comes to clipping in and out of a rope,

they simply can't be bothered, the effort of leaning down, unclipping

and clipping on to the top rope is too much for a lot of people.

And they start to think that they'll move quicker if they don't do those things.

The climb to Camp 3 is only 700m

but it has taken over five hours.

Dan, Maryam and Vijay are first to arrive.

Chris follows behind and Sundeep comes last to make sure nobody gets left on the Lhotse Face.

It has been a hard day and the team need rest before continuing tomorrow.

This small cluster of tents

is a stop-off for all the teams on Everest.

From here the final camp before the summit is just a few hours' climb away.

-Have you got a headache?

-I had a bit of one, my first one.

I think I'm dehydrated. We should get the stove on and get going.

A climber from another team is struggling to make the last few metres before camp.

He could barely move.

All the time, he's breathing as hard and as fast as he can

but having complete air hunger and feeling that nothing's going on.

If you combine that with somebody who's got this single thought in his mind that if he continues

to follow this rope he's one step nearer reaching the summit of Everest.

Actually all he was doing was climbing closer and closer to death.

And at that point I just thought, if we're going to be stood here, we might as well go down and help.

Vijay, don't go down there without being clipped on.

Just clip on and stay safe.

'It's very treacherous ground round there and if you take a fall,

'you're not clipped into anything and you're just going to keep on going to the bottom of the Lhotse Face.'

He was really in bad shape when I arrived at him.

He was completely incoherent, just making gargling noises.

Can you take his pack, Vijay?

'Er, I tried to give him some water but he couldn't swallow -'

the classical signs of HACE really.

-We'll get the oxygen down here as well.

-He needs to be up here, Vijay.

The doctors realise that this is a potentially fatal situation.

But the sick climber's team seem reluctant to help.

They call their own doctor at base camp for advice.

In the last half-hour, we've seen a complete disregard for human life.

We've seen a bunch of guys sitting in their tents

while they watch their team member struggle like hell up those ropes.

They just looked on, took photos, took out the video camera.

They came to us guys to step in and drag him up. They thanked us

for it but what were they doing?

That's everything that is wrong with people.

With light failing there is very little time to act.

If the climber is to be carried down the Lhotse Face they must leave immediately.

My name is Daniel, I'm a British doctor.

The man here is very unwell...

With the other team reluctant to take advice Dan calls the doctor directly

to try and persuade him the situation is extremely serious.

I think his life is in danger.

If he comes to Camp 2, our doctors there may be able to look after him.

We have a lot of doctors at Camp 2.

VOICE CRACKLES OVER RADIO

Yeah, we need a stretcher right away.

We've just seen another guy who's unconscious on the ropes...

On the ropes passing the camp another crisis is unfolding.

A climber returning from the summit is in trouble.

Your emotions are torn between concern for those you're trying to help,

you're concerned about the, er the health and morale

of your team that are now running around expending energy

and potentially making themselves sick when they should be resting.

But actually you realise you're fairly helpless.

Vijay, what's the score?

It's not our decision, we can only help.

Vijay, they can still get this guy down.

And that is the right treatment.

-Vijay!

-Vijay!

They'll get him down!

-Vijay!

-Vijay!

Dealing with two casualties will leave the team dangerously stretched.

Vijay should come back really. Vijay!

-Vijay!

-Come back!

Leave it!

It's awful to say this - we have to look after ourselves rather than endanger ourselves.

Vijay!

I've never ever been in this position.

We have to look after ourselves.

We really have got ourselves into a right pickle.

Drugs and oxygen can help, but the only guaranteed treatment is to descend to a lower altitude.

Taking the climber down will save his life.

Vijay, you're a good man.

But time is running out for the other climber. His team are still making no attempt to leave.

Sundeep radios for support.

OK, I'll see what I can do. I doubt it'll help but we'll see.

He wants to get everyone mobilised

to put maximum pressure on this team to bring their climber down.

'He's going to die and they're aware of that.

'They've decided to keep in the area.'

OK, I'll go into the camp and discuss it with the doctor,

It's unclear whether they're unconcerned or don't understand

or don't want to pay their Sherpas for an extra carrier.

The motivation is confusing.

I can't imagine anybody I climb with saying, "Oh, it'll be OK."

I've spoken to the doctor in the team and the leader

and they don't feel any great degree of urgency unfortunately.

-It's very frustrating being down here.

-It is, yes.

You now wait and see if he lives or dies.

If they're not going to accept any help, then...

OK, thanks very much.

I'll read this guy the riot act one more time.

We are all doctors with a lot of experience

in England in high altitude medicine.

We believe that if he stays the night here, he has a very high chance of dying.

Our advice to you is that you get him down immediately.

The summit is not important, he is important.

He should have been turned around a long time ago.

I don't...this is my doctor down here...

With respect to your doctor, he will die.

Is your doctor here or down there?

OK, well, we are doctors here who've seen your friend

and we don't think that he will survive.

VOICE CRACKLES OVER RADIO

They have finally agreed to take their climber down, but it is too late.

Night is falling and it is

too dangerous to descend the Lhotse face.

Dan in particular spent a lot of that evening treating this guy.

The impression that we had was that they were prepared to allow one of their team members

to potentially die, so that they wouldn't have to sacrifice their high position on the mountain,

and therefore their summit attempt.

It has been an exhausting experience and they've only just prevented a death.

Despite being physically drained,

early tomorrow the doctors will push on to Camp 4.

When they get there

they will set up the highest laboratory the world has ever seen.

There's a lot of drama going on on the mountain.

Over the next two days they will be tested as scientists, stretched as doctors

and pushed beyond their limits as climbers.

No hand orders. Not hand orders.

We're just going to turn around and go back down

because it's the right thing to do, you know?

If one person is up there, close to death and nobody's rescuing them,

there's nothing we can do.

But nothing can prepare them for life in the Death Zone.

-I don't like working off luck.

-'Mike, this is Denny, over?

'Mike, this is Denny. Do you copy?'

Subtitles by Red Bee Media Ltd