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2007
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Viagra May Help Severe Altitude Sickness
By Miranda Hitti
WebMD Medical News Reviewed By Brunilda Nazario, MD
on Tuesday, February 01, 2005
Feb. 1, 2005 -- A new use for Viagra may be in the works. The erectile
dysfunction drug may help protect against lung problems resulting
from high altitudes, say French researchers.
High altitude can sometimes cause illness, especially
in people with existing heart and lung problems. The thinner air
or lack of oxygen at higher altitudes can cause blood vessels to
constrict. When this occurs within the lungs, the constriction of
blood vessels can put more force on the heart, leading to life-threatening
heart failure. The higher altitude can cause blood vessels in the
lung to leak fluid and build up in the lung, interfering with oxygen
exchange.
Viagra works by relaxing blood vessels, allowing
more blood to flow freely through vessels. The researchers used
this drug to block the effects of high altitude on blood vessels
on the lung. They looked at whether the use of Viagra would help
the lungs continue to get oxygen while ascending to higher altitudes.
In a recent experiment, Viagra was better than
a placebo at protecting men's lungs. The results appear in the February
issue of the American Journal of Respiratory and Critical Care Medicine.
This was no ordinary lab test. Instead, 12 men
perched on a French mountain about 2.7 miles (4,350 meters) above
sea level, pushing their lungs to the limits in the name of science.
The participants were normal, healthy men around
29 years old. They weren't mountaineers. None was used to high altitudes.
The closest any of them had gotten to Mount Everest was probably
seeing it in a photo.
But they were in for an adventure when they enrolled
in the study.
High-Altitude Tests
Jean-Paul Richalet, MD, PhD, and colleagues wanted
to see if Viagra (sildenafil) helped stop dangerous high-altitude
health conditions.
High-altitude pulmonary edema (HAPE) occurs when
high altitude and low air pressure causes fluid to leak from blood
vessels and builds up in the lungs. HAPE has a mortality rate of
44% if untreated, say the researchers. It's triggered by intense
physical exertion at high altitudes that people aren't accustomed
to.
The study started at sea level, where the men had
baseline measurements taken. Then they left their normal lives behind
for the mountains.
First stop: Chamonix. The French mountain town
is located about 0.6 miles (1,035 meters) above sea level in the
Alps, near the Swiss border. The men spent a day there to start
adjusting to altitude. The next day, they strapped into a helicopter
and soared almost 10,000 feet (3,000 meters) higher to Observatoire
Vallot, located just below the summit of Mont Blanc, the highest
point in Western Europe.
For five days, they stayed in the mountain observatory.
Afterwards, they came back down the mountain for follow-up tests.
While on the mountain, the men filled out surveys
checking for signs of acute mountain sickness three times a day.
Their breathing was also monitored at rest. In addition, they rode
stationary bikes until they couldn't pedal any more, exercising
until exhaustion on their second and fifth days on the mountain.
Half of the men received Viagra. The rest were
given a placebo. The Viagra group took 40 milligrams of the drug
three times a day, starting on their first day on the mountain.
At first, both groups struggled to adjust. "Subjects
suffered from acute mountain sickness until day four," say
the researchers.
High altitudes caused a host of problems. Their
blood pressure rose 29% higher than at sea level. Dizziness and
stomach problems were similar in both groups.
After one or two days, the Viagra group's blood
pressure started to normalize. By the sixth day, it was 6% lower
than before the experiment. But for the placebo group, it remained
high, leveling off about 21% higher than normal.
As expected, high altitude made breathing rougher
for all of the men. But the Viagra group had less of a setback at
rest and during exercise than the placebo group. Side effects were
minor, such as muscle pain, say the researchers.
More studies should be done to see if Viagra can
replace the current treatment (calcium-channel blockers or steroids)
to treat HAPE, say Richalet and colleagues.
source:-http://my.webmd.com | 
