Medicine reaches new heights

Researchers are looking to Mount Everest for clues about how to best care for critically-ill patients at sea level

WHAT DOES climbing Mount Everest have in common with being critically ill at sea level? At first glance maybe not much, but if you zone in on the physiology the similarities become clearer, and a project is using the world’s highest mountain as a lab to find out more.

Patients in intensive care and climbers scaling to high altitudes both experience “cellular hypoxia”, where cells have low levels of oxygen, explains Dr Mike Grocott, director of the Centre for Altitude, Space and Extreme Environment Medicine at University College London.

“We think that investigating healthy people at altitude is a useful model for people with critical illness,” says Grocott, who is also a consultant in intensive care medicine at Southampton General Hospital.

He led the Caudwell Xtreme Everest expedition that gathered samples from almost 200 healthy climbers at sea level and then as they went up the mountain, and he was due to present emerging results from the project in person at the Royal College of Surgeons in Ireland.

But the activity of another volcanic mountain meant Grocott’s flight was grounded at the last minute, so he gave the lecture over a video link instead.

The rationale behind testing climbers as they ascend to high altitude is to better understand how the body adapts to the cellular hypoxia and eventually lead to improved care of critically ill patients, explains Grocott in a phone call before the talk.

The undertaking grew out of a combined interest in climbing and medicine.

“I and a number of colleagues had experience in high altitude mountaineering and in parallel with that we were going through our medical training and learning about physiology, intensive care and anaesthesia,” he recalls.

“A lot of the physiology is similar to what you see at altitude, and it’s all about oxygen flux and oxygen metabolism.”

After some “pub talk”, a team firmed up plans for the ambitious research and with funding from a number of grant-aiding bodies, companies and philanthropist John Caudwell, the expedition took place in spring of 2007.

They tracked almost 200 volunteers as they ascended the mountain at exactly the same pace, taking samples and running tests at fixed points towards base camp at 5,300m.

The project took in plenty of useful information, from DNA samples at sea level to tracking biomarkers, blood gases and flow, organ function, cognitive tests and oxygen use at rising altitude.

And from such a large group of volunteers the researchers can now examine the variation between individuals and better understand the mechanisms that allow some people to be “good” adapters, while others are less well able to cope with altitude, explains Grocott.

Other projects on the same trip also saw some of the team – including Grocott and some Irish doctors – ascend to the 8,850m summit and carry out sophisticated tests under even more extreme circumstances.

“It’s great to have had the opportunity to climb Everest,” he says. “But we were so focused on the science and making sure we stayed safe that it wasn’t quite an anti-climax to reach the top, for me getting back down to base camp with the data and everyone being safe was the magic moment.”

Three years on, the team is now sitting on another mountain – of data. “We have barely begun,” says Grocott. “And as with all science we have more questions now than when we started.”

But he stresses that the elegance of the mountain model is that it is easier to tease out particular phenomena, such as changes relating to cellular hypoxia, than it is in patients who are in intensive care, where there are other confounding issues.

“It’s a signal to noise problem – there’s lots of noise and you can’t see the signal,” he explains. “In the altitude model there’s more signal and less noise.”

Already the team has made discoveries about changes in cellular biochemistry and metabolism at increasing altitude and there’s plenty more to come, according to Grocott.

“We have got a huge number of bio- markers in the blood and we are going through those to try and understand the mechanisms,” he says. “We are trying to identify patterns or signatures of good adaptation and less good adaptation, and if that signature maps on to the critically ill patient, then we can make measurements of the biomarkers earlier and say, ‘this patient is going to do well’ or ‘this one isn’t’, and we take them to intensive care.”

Nailing down the biomarkers linked with cellular hypoxia could also point the way towards better treatments for people who are critically ill, adds Grocott.

“You can drill down and start to do empirical studies to find out if there are interventions we can use – is there a drug, for example, that we can give to the poor adapters and turn them into good adapters,” he says.

“There are potentially a whole load of applications across respiratory medicine, cardiac medicine and for other organs that suffer with hypoxic injuries such as the brain, kidneys and gut.”

Plans are now afoot to return to Everest and gather more data, including research to look at how native highlanders and lowlanders cope with the environment, says Grocott. “We will be at this for years.”