High-altitude research targets mountain sickness

Tests being carried out in the Margherita hut swissinfo.ch

An international team of researchers has spent the past month in Switzerland’s highest mountain hut investigating new treatments for altitude sickness.

The group’s common interest is high altitude pulmonary edema (HAPE) – a life threatening condition that can occur when people ascend a mountain too quickly.

The condition causes fluid retention in the lungs, with victims suffering from shortness of breath, extreme tiredness and coughing up blood. As the symptoms worsen, unconsciousness or coma and death will occur.

Half the team spent two days walking up to the hut to avoid suffering from the illness that they are trying to cure.

Other members of the group flew in by helicopter from Zermatt with four tons of equipment from Zurich University Hospital.

Throughout August they have been based in the Margherita hut, perched on top of the Signalkuppe at 4,554 metres in the Monte Rosa Massif.

High pressure

Last month, 30 climbers who have already suffered from pulmonary edema and ten who are resistant to the condition were subjected to a battery of tests at low altitude in Zurich.

Since then, the mountaineers have been walking up to the Margherita hut in groups of three for a repeat examination.

“We are focusing on the mechanism of high altitude pulmonary edema,” Marco Maggiorini from Zurich University Hospital told swissinfo.

“The question is whether blood pressure in the pulmonary artery [leading from the heart to the lungs] plays a major role in the development of pulmonary edema or whether the reabsorption of the water from the lung to the blood is a key feature too.”

The team is looking at the effects of two drugs – one of which decreases pulmonary artery pressure, while the other boosts water reabsorption.

Side effects

Although Nifedipine – a drug used for high blood pressure – is an effective treatment for pulmonary edema, it has shortcomings.

Because it doesn’t act specifically on the lung, patients can experience a drop in blood pressure and suffer from side effects including dizziness and headaches.

“Modern treatments for any disease should focus on drugs which specifically act where the problem is and not have other side effects,” said Maggiorini, lead investigator of the study.
He added that the altitude research at the Margherita hut would not only benefit mountaineers.

“What we learn up there tells us a lot about the behaviour of the lungs in conditions with poor oxygen and this knowledge can afterwards be translated to patients suffering from low oxygen concentrations in their blood.”

Low relief

Pulmonary edema is not dangerous if victims recognise the symptoms early and return to lower altitude as rapidly and safely as possible. But severe cases can result in death.

In the late 1990s, Maggiorini’s team found an explanation for what causes the condition. They discovered that elevated pressure in the lung capillaries (tiny blood vessels) leads to water in the lungs.

Previous hypotheses were that air pressure at higher altitudes caused swelling in the capillaries or that the capillaries became leaky as a result of inflammation.

Partners in the study include the University Clinic of Medicine, Heidelberg, Germany, the Erasmus University Hospital, Brussels, and Basel University Hospital.

The group will meet next spring to discuss their latest results.

swissinfo, Vincent Landon

Key facts

Acute mountain sickness can affect anyone who ascends too rapidly to high altitude (typically above 2,400 metres).
The mainstay of treatment is to return to lower altitude as rapidly and safely as possible.
Most cases are mild and symptoms improve quickly on descent. Severe cases may result in death.
Mountaineers are advised to make gradual ascents and sleep at a lower altitude wherever possible.