BP Basics

The Relationship between High Blood Pressure and High Altitude

Mountaineering and rock climbing are a passion of millions of people. Many people take up such sports for the love of nature, while others for the adventure and thrill of high altitudes. In spite of the thrills, one should not neglect the relationship between high blood pressure and high altitude.

The normal oxygen concentration at sea level is about 21% and the air pressure is about 760 mmHg. The higher we go above seal level the lower is the concentration of oxygen in the atmosphere. The atmospheric pressure also decreases with increase in altitude and at an altitude of  29,000 feet (or 8,800 meters) the atmospheric pressure is about one third in comparison to that at sea level.  

When moving to higher altitudes the combined effect of lower oxygen concentration with decreased pressure leads to physiological changes in the body. Difficulty in breathing due to lower oxygen concentration in the atmosphere, medically known as hypoxia, is a major cause of concern. This condition leads to increased respiration and high blood pressure.

At high altitude, hypoxia may cause constriction of  blood vessels in the lungs. This condition causes the blood pressure in these vessels to rise. This can either cause hardening of the arteries or the weakened artery walls to bulge. That is why mountaineers usually stay at each level to acclimatize themselves.

The increased blood pressure dilates the blood vessels of the body. This results in the heart pumping more blood, thus pushing it to work at an elevated speed. As the heart works harder, trying to force the blood through, the decreased atmospheric pressure causes less blood to flow through the lungs to pick up oxygen. This makes patients with high blood pressure tired, dizzy and breathless.

Thus, it is advised that people with high blood pressure should keep a check on their blood pressure. A frequent monitoring of blood pressure is required to pre-empt or prevent any medical emergency that might take place.