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Blood Pressure

Blood Pressure -Is the measure of the pressure exerted by the blood as it pulsates through the arteries.
a. BP=Cardiac Output x Total Peripheral Resistance or CO x TPR
b. Systolic Pressure -Is the pressure of blood as a result of contraction of the ventricles (100-140 mm Hg)
c. Diastolic Pressure –Is the pressure when the ventricles are at rest (60-90 mm Hg )
d. Pulse Pressure –Is the difference between the systolic and diastolic pressures ( S-D=P.P. ) Normal is 30-40 mm Hg
e. Hypertension –Is an abnormally high blood pressure over 140 mm Hg systolic and or above 90 mm Hg diastolic for at least three consecutive readings
f. Hypotension –Is an abnormally low blood pressure, systolic pressure below 100/60 mm Hg

Determinants of Blood Pressure
1. Blood Volume –Hypervolemia raises BP, hypovolemia lowers BP
2. Peripheral Resistance –Vasoconstriction elevates BP. Vasodilation lowers BP.
3. Cardiac Output –When the pumping action of the heart is weak (decreased CO), BP increases
4. Elasticity or Compliance of Blood vessels –In older people, elasticity of blood vessels decreases thereby increasing BP.
5. Blood viscosity ( viscosity increases markedly when Hct is more than 60-65% ) Increased in blood viscosity raises BP.

Factors Affecting Blood Pressure
1. Age. Older people have higher BP, due to decreased elasticity of blood vessels.
2. Exercise. Increases cardiac output; hence the BP.
3. Stress. Sympathetic nervous system stimulation causes increased BP.
4. Race. Hypertension is one of the 10 leading causes of death among Filipinos.
5. Obesity. BP generally is elevated among overweight and obese people.
6. Sex/Gender. After puberty and before age 65 years, males have higher BP. After age 65 years, females have higher BP due to hormonal variations in menopause.
7. Medications. Some medications may increase or decrease BP.
8. Diurnal Variations. BP is lowest in the morning and highest in the late afternoon or early evening.
9. Disease Process. Diabetes Mellitus, Renal failure, hyperthyroidism, Cushing’s disease cause increase in BP.

Assessing Blood Pressure
1. Ensure that the client is rested
2. Allow 30 minutes to pass if the client had engaged in exercise or had smoked or ingested caffeine before taking the BP. These factors tend to increase BP.
3. Use appropriate size of the BP cuff. Too narrow cuff causes false high reading. Too wide cuff causes false low reading.
4. Position the client in sitting or supine position.
5. Position the arm at the level of the heart, with the palm of the hand facing up. The left arm is preferably used because it is nearer the heart.
6. Apply BP cuff snugly, 1inch above the antecubital space.
7. Determine palpatory BP before auscultatory BP to prevent auscultory gap.
8. Use the bell of the stethoscope since the blood pressure is a low frequency sound.
9. Inflate and deflate BP cuff slowly, 2-3 mm Hg at a time.
10. Wait 1-2 minutes before making further determinations.
11. The sound during BP taking is Korotkoff sound.
12. Read lower meniscus of the mercury level of the sphygmomanometer at eye level to prevent error of parallax.
*Error of Parallax occurs in this manner. If the eye level is higher than the level of meniscus of the mercury, this causes false low reading, if the eye level is lower, this causes a false high reading.
13. The systolic pressure in the popliteal artery is usually 10-40 mm Hg higher than that in the brachial artery; the diastolic pressure is usually the same.


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