Ibuprofen May KO Altitude Sickness
If you long for a “Rocky Mountain high” but not the headache, fatigue, dizziness, nausea, and vomiting that sometimes accompany a climb, fear not.
A randomized placebo-controlled trial found that ibuprofen reduces the incidence of mountain sickness, according to Grant Lipman, MD, of Stanford University School of Medicine in Stanford, Calif., and colleagues.
The nonsteroidal anti-inflammatory also appeared to reduce the severity of illness, Lipman and colleagues reported online in Annals of Emergency Medicine.
The issue is important for tourists, recreational mountaineers, military operations, and search and rescue missions, where participants often don’t have time to prepare for the climb.
A slow ascent, allowing the body to acclimate, can reduce the chances of the condition, which Lipman said in a statement is like “a really nasty hangover.” As well, prescription medications are available but they have significant risks and have to be taken well before the climb starts.
In contrast, ibuprofen is well tolerated, widely available, and can be taken the same day as the climb, the researchers reported.
The Causes of Altitude Sickness
The percentage of oxygen in the atmosphere at sea level is about 21% and the barometric pressure is around 760 mmHg. As altitude increases, the percentage remains the same but the number of oxygen molecules per breath is reduced. At 3,600 metres (12,000 feet) the barometric pressure is only about 480 mmHg, so there are roughly 40% fewer oxygen molecules per breath so the body must adjust to having less oxygen.
In addition, high altitude and lower air pressure causes fluid to leak from the capillaries in both the lungs and the brain which can lead to fluid build-up. Continuing on to higher altitude without proper acclimatisation can lead to the potentially serious, even life-threatening altitude sickness.
“If you are heading to the mountains,” Lipman said, “take some ibuprofen the day you go.”
The exact causes of mountain sickness are not known, but there is some evidence it is a result of an inflammatory process, Lipman and colleagues noted. So, it made sense to test ibuprofen in a group of 86 healthy adult volunteers who live at low altitude.
The following actions can trigger altitude sickness:
Ascending too rapidly
Overexertion within 24 hours of ascent
Inadequate fluid intake
Hypothermia
Consumption of alcohol or other sedatives
One way to avoid altitude sickness is allowing the body to get used to the altitude slowly.
Acclimatization is the process by which the body adjusts to high altitudes.
The goal of acclimatization is to increase ventilation (breathing) to compensate for lower oxygen content in the air.
To compensate for this extra ventilation, blood needs to have a lower pH. In response, the kidneys excrete bicarbonate into the urine, which in turn lowers the body’s pH to accommodate for this extra respiratory effort.
During July and August 2010, in the White Mountains of California, the volunteers were randomly assigned to take 600 milligrams of ibuprofen or an identical-appearing placebo three times a day.
The study began at an altitude of 1,240 meters (4,100 feet) at 8 a.m., after the volunteers completed questionnaires covering acute mountain sickness symptoms and demographics, had their oxygen saturation measured and received the first dose of medication.
Volunteers were then driven to a staging area at 3,545 meters (11,700 feet) and received the second medication dose at 2 p.m. Then they hiked about 4.3 kilometers (2.7 miles) to 3,810 meters (12,570 feet), where they took the third dose at 8 p.m. They spent the night and received a final dose the following morning.
The primary outcome measures were incidence and severity of mountain sickness, as calculated on the Lake Louise Questionnaire, Lipman and colleagues reported.
They found that 19 volunteers in the ibuprofen group (43%) developed acute mountain sickness compared with 29 in the placebo group (69%), for an odds ratio of 0.3 (95% CI from 0.1 to 0.8).
The number needed to treat to prevent one case of acute mountain sickness was 3.9 (95% CI 2 to 33).
Mountain sickness severity was higher in those who became ill in the placebo group than in those who became sick while taking ibuprofen - 4.4 versus 3.2 on the questionnaire, on average - but the difference was not statistically significant (mean difference 0.9%, 95% CI 0.3% to 3%).