Nursing Care Related to the
Cardiovascular and Respiratory Systems 1-20 |
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1-20. BLOOD PRESSURE
a. Blood pressure is defined as the pressure exerted by the blood on the walls of the blood vessels. When speaking of blood pressure, it is the arterial blood pressure that we are concerned with. When taking a patient's blood pressure with a sphygmomanometer and stethoscope, it is the arterial blood pressure that is being measured.
b. Blood pressure is registered by two numbers that represent the pressures exerted during contraction and relaxation of the heart.
c. Blood pressure is best measured over a large artery. The most commonly used is the brachial artery. The cuff is wrapped around the upper arm and auscultation is done over the brachial artery in the antecubital space.
d. Blood pressure depends upon the force of the heartbeat, the volume of blood in the circulatory system, and the resistance within the blood vessels. Other factors that affect blood pressure are:
(1)
Pain. Moderate to severe pain will increase blood pressure.
(2)
Emotions. Fear, anger, anxiety, or excitement will increase blood pressure.
(3)
Disease. Disease conditions may cause abnormal increase or decrease of blood pressure.
e. In patients with hypertension or other cardiovascular disease, it is best to measure blood pressure in both the right and left arms. There should be no more than 5 mmHg difference between the two readings. A greater difference is indicative of vascular disease.
f. The physician may order blood pressure checks to be done with the patient lying down, sitting, and standing. The corresponding rise or fall in pressure with the change of position may give the physician valuable information about the nature of the cardiovascular disease.
g. Pulse pressure is the difference between the systolic and diastolic pressures. Normal range for pulse pressure should be 30-50 mmHg, with 40 mmHg the average.
(1) A decreased pulse pressure (less than 30 mmHg) is related to factors that cause an increase in the diastolic blood pressure, a decrease in systolic blood pressure, or a combination of both. Causes of decreased pulse pressure included peripheral vasoconstriction, aortic valve stenosis, mitral valve insufficiency, or decreased stroke volume due to heart failure or hypovolemia.
(2) An increased pulse pressure (greater than 50 mmHg) is related to factors that cause a decrease in the diastolic blood pressure, an increase in systolic blood pressure, or both. Causes of increased pulse pressure include hypertension, circulatory overload, arrhythmias, increased stroke volume caused by anxiety or exercise, or decreased distensibility of the arteries as seen in arteriosclerosis and aging.
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