Blood Pressure

3. Examine your laboratory partner's radial pulse. To do this, follow these steps:

a. Have your partner sit quietly, remaining as relaxed as possible.

b. Locate the pulse by placing your index and middle fingers over the radial artery on the anterior surface of the wrist. Do not use your thumb for sensing the pulse, because you may feel a pulse coming from an artery in the thumb itself.

c. Note the characteristics of the pulse. That is, could it be described as regular or irregular, strong or weak, hard or soft?

d. To determine the pulse rate, count the number of pulses that occur in 1 minute. This can be accomplished by counting pulses in 30 seconds and multiplying that number by 2.

4. Repeat the procedure and determine the pulse rate in each of the following conditions:

a. immediately after lying down;

b. 5 minutes after lying down;

c. immediately after standing;

d. 5 minutes after standing quietly;

e. immediately after 3 minutes of strenuous exercise (omit if the person has health problems);

f. 5 minutes after exercise has ended.

5. Complete Part B of the laboratory report.

DEMONSTRATION

i f the equipment is available, the laboratory instructor will demonstrate how a photoelectric pulse pickup transducer or plethysmogram can be used together with a physiological recording apparatus to record the pulse. Such a recording allows an investigator to analyze certain characteristics of the pulse more precisely than is possible using a finger to examine the pulse. For example, the pulse rate can be determined very accurately from a recording, and the heights of the pulse waves provide information concerning the blood pressure.

6. Measure your laboratory partner's arterial blood pressure. To do this, follow these steps:

a. Obtain a sphygmomanometer and a stethoscope.

b. Clean the earpieces and the diaphragm of the stethoscope with cotton moistened with 70% alcohol.

Figure 45.1 Blood pressure is commonly measured by using a sphygmomanometer (blood pressure cuff).

Mercury column

Figure 45.1 Blood pressure is commonly measured by using a sphygmomanometer (blood pressure cuff).

Anatomy Antecubital Space

Mercury column

Antecubital space (location of brachial pulse and stethoscope placement)

Location of radial pulse

Antecubital space (location of brachial pulse and stethoscope placement)

Location of radial pulse c. Have your partner sit quietly with bare upper limb resting on a table at heart level. Have the person remain as relaxed as possible.

d. Locate the brachial artery at the antecubital space. Wrap the cuff of the sphygmomanometer around the arm so that its lower border is about 2.5 cm above the bend of the elbow. Center the bladder of the cuff in line with the brachial pulse (fig. 45.1).

e. Palpate the radial pulse. Close the valve on the neck of the rubber bulb connected to the cuff, and pump air from the bulb into the cuff. Inflate the cuff while watching the sphygmomanometer and note the pressure when the pulse disappears. (This is a rough estimate of the systolic pressure.) Immediately deflate the cuff.

f. Position the stethoscope over the brachial artery. Reinflate the cuff to a level 30 mm Hg higher than the point where the pulse disappeared during palpation.

g. Slowly open the valve of the bulb until the pressure in the cuff drops at a rate of about 2 or 3 mm Hg per second.

h. Listen for sounds (Korotkoff sounds) from the brachial artery. When the first loud tapping sound is heard, record the reading as the systolic pressure. This indicates the pressure exerted against the arterial wall during systole.

i. Continue to listen to the sounds as the pressure drops, and note the level when the last sound is heard. Record this reading as the diastolic pressure, which measures the constant arterial resistance.

j. Release all of the pressure from the cuff.

k. Repeat the procedure until you have two blood pressure measurements from each arm, allowing 2-3 minutes of rest between readings.

l. Average your readings and enter them in the table in Part C of the laboratory report.

7. Measure your partner's blood pressure in each of the following conditions:

a. immediately after lying down;

b. 5 minutes after lying down;

c. immediately after standing;

d. 5 minutes after standing quietly;

e. immediately after 3 minutes of strenuous exercise (omit if the person has health problems);

f. 5 minutes after exercise has ended.

8. Complete Part C of the laboratory report.

Laboratory Report

Section.

Essentials of Human Physiology

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