Having something to eat and drink is the simplest method of increasing the circulating blood volume for air travelers. Medical personnel and travelers should know that hunger can cause in-flight emergencies, and fluid is probably even more effective in preventing emergencies. Older individuals and those with high blood pressure or vascular disorders are especially at risk for these types of emergencies. Low cabin pressure at higher altitudes causes blood vessels in the peripheral circulation and organs to expand as the body attempts to increase its oxygen supply. However, the amount of blood pumped by the heart remains the same.
Many people experience an unpleasant feeling in-flight.
I sometimes get a headache or feel cold or tired, which is similar to the slight sickness caused by low in-flight air pressure. Treatment is usually unnecessary. We wanted to know what causes this oxygen reduction. Blood pressure does not change if the circulating blood volume is high enough. However, it is possible to have a blood-pressure decrease and oxygen deficiency in the organs if the amount of blood circulating in the body is too low to accommodate expanded blood vessels, and this may be affected by dehydration, says Matsumura.