Mountain Climbers Aid Research on Altitude Sickness
April 23, 2001 -- Why would someone climb a 15,000-foot mountain and then let a doctor insert a catheter into their heart?
"Climbers are a bit crazy," Marco Maggiorini, MD, tells WebMD. "They like to go to the mountains and they want to keep going; they don't want to get ill. [The climbers we studied] wanted to learn what they could do to prevent altitude problems."
In their study, Maggiorini and colleagues used heart catheterization to look at pressure in tiny blood vessels within the lung, first at low altitude in Zurich, Switzerland, and then in the highest shelter in the Swiss Alps. This process meant the doctors punctured a neck vein in the climbers and ran a tiny tube through the heart and into the pulmonary artery.
"It's not painful, though you might feel a few extra heart palpitations," says Maggiorini, whose study was published in the April 24 issue of Circulation: Journal of the American Heart Association. He is an assistant professor and chief of the intensive care unit in the medical department at University Hospital in Zurich.
Thirty climbers participated in the study, and their efforts yielded interesting, important information about high altitude pulmonary edema (HAPE). This condition can occur when you climb rapidly to a high altitude, above 8,250 feet. Some people aren't vulnerable to the problem, but if someone does get it, it can be life threatening. Symptoms include a dry cough, air hunger, extreme tiredness, inability to walk or sleep, and coughing up blood or sputum.
"We learned that in susceptible climbers, high altitude pulmonary edema is caused by elevated pressure in the pulmonary capillaries," Maggiorini says. "Before this we weren't sure whether this was a pressure-related disease or if it was due to 'leaky' capillaries. We found it is a simple, pressure-related build-up of fluid in the lungs. Usually the blood that circulates from the heart to the lungs is under low pressure. When someone has HAPE, you could say they have high blood pressure of the lungs."
"This is a fascinating, unique study," says Michael Marcus, MD. "The authors went through a very careful analysis of the problem." Marcus is director of pediatric pulmonology and immunology at Maimonides Medical Center in Brooklyn and assistant professor of pediatrics at the State University of New York in Brooklyn.
Fortunately, Maggiorini says, HAPE can be prevented or treated with drugs such as nifedipine, sold as Procardia and Adalat. "People who've had a previous episode of water on the lungs and plan to go climbing again should talk with their doctor about taking nifedipine with them when they travel," he says.
Marcus is more cautious.
"Nifedipine is a calcium channel blocker and will also decrease blood pressure in general," he says. "It is not something we can [recommend] just yet, ... but it would be appropriate to take a second look at this issue through a clinical study."