5-3. WHAT FACTS AFFECT A PERSON'S BLOOD PRESSURE?

There are several factors that can affect a patient's blood pressure. Some are only temporary; others are long-term effects. A condition in which the blood pressure is considerably above normal is called "hypertension." If the blood pressure is too low, it is called "hypotension."

a. Condition of Cardiovascular System. A primary factor influencing a patient's blood pressure is the condition of his cardiovascular system (heart and blood vessels).

(1) If a patient's heart is not pumping blood with enough force, his blood pressure will be low. This will decrease the rate that blood is circulated throughout the body. Slow blood circulation may result in certain parts of the body (especially the brain) not receiving enough oxygen since oxygen is carried by the blood.

(2) If a patient's heart is pumping with too much force, his blood pressure will be high. If an artery has a weak spot, the force of the systolic pressure may be enough to rupture the artery and allow blood to escape.

(3) If a patient's arteries loose part of their elasticity, such as in patients who have arteriosclerosis (hardening of the arteries), the patient's blood pressure will be higher, since the artery walls stretch less and cannot relieve as much pressure.

b. Age. A person's blood pressure readings tend to increase as he grows older.

c. Gender. As indicated in paragraph 5-2, men tend to have higher blood pressure than women of the same age.

d. Physical Fitness. People who are physically fit tend to have more normal blood pressure than people who are "out of shape."

e. Obesity. People who are very overweight usually have higher blood pressure than they would if their weight were closer to their ideal weight.

f. Pain. Pain is a type of body defense that lets the brain know that something is wrong. The brain may respond to pain by increasing the rate and strength of heartbeats. The increased rate increases the amount of oxygen available to the muscles for producing energy. It also results in an increased blood pressure.

g. Emotion. Fear, worry, excitement, and similar emotions can result in a higher blood pressure. The brain may react to these emotions in basically the same way that it reacts to pain.

h. Gravity. If a person is standing, the blood pressure of the arteries in the lower part of the body will be greater than the pressure in the upper part of the body.

i. Exercise. A person's blood pressure is greater during and just after exercising because the heart beats faster in order to supply additional oxygen to the muscles.

j. Disease. Almost any disorder that affects the arteries or the renal (kidney) system will result in a higher blood pressure. Diseases that weaken the heart will usually result in a lower blood pressure.

k. Drugs. Drugs designed to strengthen the actions of the heart, such as digitalis, will cause the patient's blood pressure to rise. Drugs that cause the arteries to become smaller in diameter (called vasoconstrictors) will also cause the patient's blood pressure to rise. Drugs that cause the patient's arteries to become larger in diameter (called vasodilators) will decrease blood pressure.

l. Eating. A person's blood pressure is usually elevated (increased) while he is eating and for a while after he finishes the meal.

m. Bleeding. Serious bleeding (hemorrhaging) reduces the amount of blood in the body's circulatory system and thus reduces blood pressure.