Name:Date:

Lab: Blood Pressure and Pulse Determinations

PART 1: Pulse

Objective:Define pulse and accurately determine a subject’s radial and apical pulse. The term pulse refers to the alternating surges of pressure in an artery that occur with each beat of the left ventricle. Normally, the pulse rate equals the heart rate and the pulse averages 70 to 76 beats per minute in the resting state.

Background Information:Palpating Superficial Pulse Points:

The pulse may be felt on any artery close to the body surface when the artery is compressed over a bone or firm tissue. The following is a list of pulse points commonly used:

Pulse Point:Location:

Common carotid artery At the side of the neck

Temporal artery Anterior to the ear, in the temple region

Facial arteryClench teeth and palpitatethe pulse just anterior to the masseter muscle

Brachial artery In the elbow region

Radial arteryAt the lateral aspect of the wrist, just below the thumb

Popliteal arteryAt the back of the knee

Pedal arteryOn the top of your foot

Procedure:

  1. Write a hypothesis of your pulse rate in relation to exercise. Use the If, then format. (____/1)
  1. Palpate the following pulse or pressure points on your partner by placing the fingertips of the first two or three fingers of one hand over the artery.

Note: It helps to compress the artery firmly as you begin your palpitations and then immediately ease up on the pressure slightly.

  1. Take a resting pulse rate for a minute for each partner and record it in the data table.

Lab Partner 1: / Lab Partner 2:
Carotid
Temporal
Brachial
Facial
Radial
Popliteal
Pedal
  1. Plot your values on a graph. The x-axis should be the location of the pulse and the y-axis should be the pulse rate per minute. Be sure to label your axis and title your graph.
  1. Which pulse point was your strongest (greatest amplitude)?
  1. Which pulse point was your weakest (least amplitude)?
  1. Can you offer any explanation of this?
  1. Because of its easy accessibility, the pulse most often taken is on the carotid artery. With your partner sitting quietly, practice counting the carotid pulse for one minute. Make three counts and determine the average.

Count 1:

Count 2:

Count 3:

Average:

  1. Now you will take your carotid pulse after exercise. Do the following exercises to determine how your pulse rates change: jogging in place for one minute, doing 15 push-ups, lying down in your chair, and one minute of jumping jacks.
  1. Immediately following exercise, take your radial pulse for one minute. Record it in the data table.

Lab Partner 1: / Lab Partner 2:
Jogging
15 Push-ups
Laying in your chair
Jumping Jacks
  1. How did your pulse rate differ after exercise from that of your resting pulse rate?
  1. The average pulse rate of an athlete is lower than the normal average pulse rate. Explain why this is so.
  1. Why do you think the pulse is taken from arteries of the body and not veins?

PART 2: Blood Pressure

Introduction: (read very carefully to understand)

Blood pressure is the force exerted by blood against the walls of arteries and veins. It is created by the pumpingaction of the heart. Blood pressure is measured in millimeters of mercury (mm Hg) and is expressed by two

Numbers—120/80, for example. The higher number is systolic blood pressure, the maximum pressure that occurs

when the heart contracts. The lower number is diastolic blood pressure, the pressure when the heart is relaxed

between contractions.

The cardiac cycle includes events in one complete heartbeat, during which both atria and ventricles contract and then relax, and a predictable sequence of changes in blood volume and pressure occur in the heart. Pressure changes in the right side are less dramatic but the same relationships apply.

Let’s start our discussion of the cardiac cycle with the heart in complete relaxation (diastolic). Pressure in the heart is very low and the blood is flowing passively from the pulmonary vein and vena cava, then into the atriaand through the ventricle. The semilunar valves (also called the pulmonic and aortic valves) are closed and the AV valves (also called the tricuspid and mitral valves) are open. Then atrial contraction occurs and atrial pressure increases, forcing blood remaining in the atrium into the ventricles.

Then ventricular systole begins and pressure in the ventricles rapidly increases, closing the AV valves. When pressure in the ventricles exceeds that of the arteries leaving the heart (aorta and pulmonary artery) the semilunar valves open. The blood in the ventricles gushes through the valves and leaves the heart. During this phase, the pressure in the aorta reaches approximately 120 mm Hg. While the ventricles are contracting, the atria are relaxing and refilling with blood. At the end of the ventricles contracting (systole), the ventricles relax and semilunar valves close, preventing backflow. When intraventricular pressure is less than atrial pressure, the AV valves are open and then ventricles refill again. Atrial and aortic pressures decrease, the ventricles refill, completing a cycle. The average heart beats approximately 72 to 75 beats per minute and so the length of the cardiac cycle is about 0.8 seconds.

Equipment:

  • Sphygmomanometer (A sphygmomanometer consists of an inflatable bag inside a covering called a cuff,

an inflating bulb, a manometer from which blood pressure can be read, and a valve that is used fordeflation.)

  • Stethoscope
  • Chair
  • Table or other surface to support arm

Preparation:

For the person being tested: Wear clothing that allows your upper arm to be bare. Avoid heavy exercise or eating

prior to the test.

Introduction:

The sphygmomanometer, commonly called the blood pressure cuff, is an instrument used to measure blood pressure by the auscuiatory method. This method consists of an inflatable cuff with an attached pressure gauge. The cuff is wrapped around the arm just above the elbow and inflated until the cuff pressure exceeds systolic pressure to stop blood flow to the arm. As cuff pressure is gradually released, the examiner listens with a stethoscope over the brachial artery for characteristic sounds, which indicates a resumption of blood flow into the forearm. The pressure at which the first soft tapping sounds are heard is recorded as the systolic pressure. As the pressure is reduced, blood flow becomes more turbulent and sounds become louder. Below the diastolic pressure, when the artery is no longer compressed, blood flows freely and can no longer be heard. The pressure at which the sound disappears is recorded as the diastolic pressure.

Blood Pressure = Systolic Pressure (higher number)

Diastolic Pressure (lower number)

Procedure:

  1. The subject should sit comfortably, with the arm slightly flexed, palm up, and the forearm supported at

heart level on a table or other smooth surface. If such a surface isn’t available, you will need to support thesubject’s forearm while you take the measurements.

  1. Place the deflated cuff on the subject’s upper arm, with the lower edge of the cuff about 1 inch above the inner elbow crease. The inflatable bag should rest on the brachial artery, which is on the inner part of theupper arm. The cuff should be marked with an arrow as to where it should be touching the brachial artery. The inflatable bag should encircle at least 80% of the arm; if it does not, use a large sphygmomanometer.

Note: The cuff should not be kept inflated for more than 1 minute. If you have trouble finding a reading within this time, deflate, wait one minute, and try again. (A prolonged interruption in blood flow can cause fainting)

  1. Apply the stethoscope lightly to the arm, just at the inner elbow crease. Make sure the stethoscopedoesn’t touch the cuff or any of the tubing from the sphygmomanometer. Many of your kits have them already built-in.
  2. Place the cleaned stethoscope in your ears. While watching the manometer and listening for pulse sounds through the stethoscope, inflate the cuff to 160 mm Hg above the point at which pulse sounds disappear. (Inflating the bag closes off the blood flow in the brachial artery, causing the pulse sounds to stop.)
  3. Slowly deflate the cuff at a rate of 3 mm Hg per second. Watch the pressure gauge and listen for a faint heartbeat.
  4. When you hear the first sound, make note of the time but continue watching the gauge. This is your systolic pressure.
  5. Keep releasing the gauge until the sound disappears. When you no longer hear a heartbeat, record the number. This is your diastolic pressure.
  6. Wait 1–2 minutes and then repeat the test. Record both results and indicate which arm was used for the

measurements. For more accurate results, readings should be taken by several different people or on severaldifferent occasions.

Remember:

• Systolic pressure is the point at which pulse sounds first become audible. You should hear faint but

clear tapping sounds.

• Diastolic pressure is the point at which the pulse sounds disappear.

(Note: If you are measuring blood pressure as part of an exercise test, the method for determining diastolic

pressure is somewhat different. Sometimes during exercise the sounds are audible all the way down to

0 mm Hg. If this occurs, diastolic pressure is the point at which there is a definite change in the loudness of

the sound—an abrupt muffling.)

Person 1 / Type of Pressure / Left Arm (trail 1) / Right Arm (Trail 2) / Averages
Systolic Pressure
Diastolic Pressure
Person 2 / Systolic Pressure
Diastolic Pressure

Blood Pressure Classification:

Average the results of the two sets of measurements. Refer to the table below for the rating.

Person 1: Average pressure: ______/ ______Classification: ______

(Systolic) (Diastolic)

Person 2: Average pressure: ______/ ______Classification: ______

(Systolic) (Diastolic)

Categories: Systolic (mm Hg) and Diastolic (mm Hg)

Normal: Below 120 and Below 80

Prehypertension: 120–139 or 80–89

Hypertension: Stage 1 140–159 or 90–99

Stage 2 160 and above or 100 and above

Analysis:

  1. What was the most difficult part of measuring your blood pressure?
  1. Identify one possible source of error.
  1. What is considered one cardiac cycle?
  1. Summarize the diastolic phase of the cardiac cycle
  1. What events happen in the systolic phase of the cardiac cycle?
  1. About how long is the cardiac cycle?
  2. What exactly is the blood pressure cuff measuring?