Effects of High Altitude on Blood Pressure
Living at or traveling to high altitudes can raise a person's blood pressure, depending on the rate of ascent and the amount of time spent at the high altitude. The International Society of Mountain Medicine describes high altitude as 5,000 to 11,500 feet above sea level. At higher altitudes, the body works harder to process oxygen. This stress can cause high blood pressure. But the more time a person spends at the higher altitude, the better acclimatized the body becomes.
A woman stands on a rock in the mountains. (Image: Jupiterimages/Comstock/Getty Images)Acute Mountain Sickness
Acute mountain sickness is a condition that can affect mountain climbers or anyone traveling at high altitudes. If a person ascends too quickly, oxygen deprivation, or hypoxia, may develop. The oxygen deprivation causes blood vessels constriction, raising blood pressure and causing fluid to leak into the lungs. The condition can be treated with supplemental oxygen inhalation and medication to lower blood pressure. Without treatment and descent, the condition can become life-threatening.
Hypertension
Prolonged exposure to high altitudes can have a positive effect on hypertension, or high blood pressure. In his book "Medicine for Mountaineering: And Other Wilderness Activities," Dr. James Wilkerson writes that extended exposure to high altitudes may inhibit the progression of hypertension in some hypertensive individuals. Dr. Wilkerson also notes that many non-hypertensive individuals experience the opposite effect, that is, an increase in blood pressure when exposed to high altitudes.
Variable Response
In the November 2009 issue of the "Journal of Travel Medicine," Dr. Timothy O'Brien and colleagues reported on a study that found a group of black mountaineers experienced a drop in their systolic blood pressure numbers as they climbed to high altitude. Systolic pressure is the amount of force placed against the body's arterial walls when the heart contracts. It is designated by the top number in a blood pressure reading. However, the systolic pressure of white mountain climbers increased as they ascended. The cause of the racial differences is unknown and may not apply to all individuals. The authors speculated that the observed differences seen in this small study may have been due to differences in genetics, hypoxic stress, diet and exercise.
