BLOOD PRESSURE12/3/2012

SHMD 139

Blood PressureBlood pressure is the pressure the blood exerts on

the artery walls

Blood pressure (BP) is the result of the heart

contracting and forcing blood into the blood vessels

BP is necessary in order for blood to flow around the

body

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Blood Pressure

Typical BP for the average person:

120 Systolic: When the heart is contracting

80 Diastolic: When the heart is relaxing

BP unit of measurement:

milligrams of mercury (mmHg)

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Calculating Blood PressureCardiac Output: the amount of blood pumped from

the heart every minute

Stroke Volume: The amount of blood pumped by

the left ventricle of the heart in one contraction.

Heart Rate: the number of times the heart beats in

1 minute, measured in beats per minute (bpm)

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Calculating Blood PressureCardiac Output (litres per minute) = heart rate (bpm) x

Stroke volume (litres)

Thus, Q = HR x SV

The average stroke volume is 70 – 90 millilitres (ml)

The fitter you are, the larger your SV is

At rest, your cardiac output (Q) is ± 5 litres per minute

(L/m), while during exercise it can increase to as much as

30 L/m

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Calculating Blood PressureBlood Pressure (mmHg) = Cardiac Output (litres

per minute) x Resistance to flow (R)

Thus, BP = Q x R

Resistance to blood flow is caused by:

1. Size of the blood vessels. i.e. The smaller the blood

vessel, the greater the resistance

2. Thickness of the blood. i.e. The thicker the blood, the

greater the resistance.

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If heart rate = 72 bpm& stroke volume = 85mlCardiac output?

85ml ÷ 1000 = 0.085LThus,Q = HR x SV

= 72 x 0.085= 6.12 L/m

Round off = 6 L/m

Calculating Blood Pressure

If heart rate = 68 bpm Diastolic R = 14 & stroke volume = 80ml Systolic R = 22 Cardiac output? Blood Pressure? 80ml ÷ 1000 = 0.080L Thus, Q = HR x SV

= 68 x 0.08= 5.44 L/m

Systolic BP = Q x R Diastolic BP = Q x R= 5 x 22 = 5

x 14= 110 mmHg = 70

mmHg

Thus BP = 110 mmHg 70

Calculating Blood Pressure

BLOOD PRESSURE & exerciseExercise increases heart rate, which will result in an

increased cardiac output, which will increase blood

pressure

Q = HR x SV

BP = Q x R

If Q is increased, and R does not change, then BP will

automatically increase

Exercise raises systolic BP, but there is usually only a

slight change in diastolic BP

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HypertensionIs a repeatedly elevated blood pressure

exceeding 140 over 90 mmHg, and means

high pressure (tension) in the arteries.

If a person with high blood pressure does not

reduce their BP, they are more at risk of

suffering a stroke or heart attack .

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The VALSALVA MANOEUVRE Pg 35

Used by heavy weightlifters

Process of breathing against a closed glottis or

against a closed mouth & nose

The valsalva maneouvre helps stabilise the

shoulder girdle and torso while lifting heavy

weights. This helps the lifter to move the weight

more efficiently.

The VALSALVA MANOEUVREThe valsalva maneouvre causes BP to increase,

and reduces blood flow to the thoracic cavity

Thoracic cavity: part of the body that is enclosed by the

ribcage and the diaphragm, containing the heart and lungs

Therefore anyone suffering from hypertension or

heart problems should avoid this move, as it

could cause a stroke or heart attack.

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measuring BLOOD PRESSUREIt is vital to measure BP before a client exercises,

as it will tell you if they are at risk of having a

heart attack.

BP is measured with a blood pressure meter and

stethoscope.

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measuring BLOOD PRESSURE1. The client should be seated and relaxed for 5 minutes

2. Ask the client to rest their left arm on the arm of the chair. Their

elbow should be at 45 degrees, with the palm of the hand facing up.

3. Find the brachial pulse – it should be on the inner side of the arm,

just under the biceps muscle.

4. Place the cuff just clear of the elbow (about 2-3cm above the

elbow). The bladder of the cuff (The part which inflates) should be

directly over the pulse.

5. Place the earpieces of the stethoscope in your ears and place the

microphone over the brachial pulse.

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measuring BLOOD PRESSURE6. Inflate the cuff up to 200mmHg.

7. Slowly open the valve by turning it anti-clockwise and release

the pressure.

8. Listen out for the first time you hear the thud of the heart beat

and make a mental note of it. This is the systolic blood pressure

reading.

9. Keep deflating the cuff, and when the heart beat becomes

muffled or disappears, this is your diastolic reading.

10. Keep deflating the cuff and, if necessary, repeat

after around 30 seconds.

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BLOOD PRESSURE normsClassification of blood pressure for adults

Category Systolic (mmHg) Diastolic (mmHg)

Desirable 90 – 119 60 – 79

Prehypertension 120 – 139 80 – 89

Stage 1 Hypertension 140 – 159 90 – 99

Stage 2 Hypertension 160 – 179 100 - 109

Hypertensive Crises ≥180 ≥ 110

QUESTIONS1. Define:

a. Blood pressure. 2b. Cardiac output. 2c. Stroke volume. 2d. Hypertension. 2

2. What do the following abbreviations stand for:a. BP. 2b. Q. 2c. SV. 2

3. Differentiate between ‘systolic’ and ‘diastolic’ blood pressure. 2

4. Provide the unit of measurement for:a. Blood pressure. 1b. Cardiac output. 1c. Stroke volume. 1

5. Provide the average stroke volume of a person at rest? 2

6. Does stroke volume ever change? If so, when?2

7. Provide the average value of cardiac output at rest, as well as during exercise. 2

8. List and briefly explain the 2 factors that cause resistance to blood flow. 4

9. How does exercise affect blood pressure? 510.What are the implications of a high BP? 211.Explain:

a. The valsalva manoeuvre. 3b. Who uses it, 2c. And why. 2

QUESTIONS

12. Should someone with a high BP perform the valsalva maneuver? Why/why not?

313. Which two instruments are used to measure BP?

214. Why is it important to measure BP before an individual

performs exercise testing?3

15. Explain the procedure for measuring blood pressure.10

16. In tabular form, write down the norms for blood pressure. 16

QUESTIONS

Calculate:1. Calculate cardiac output (Q) of a person at rest; if their heart rate

is 72 bpm, and their stroke volume is 75 ml (0.075L).3

2. Calculate the cardiac output of a person who is training at a high intensity; if their heart rate is 180 bpm, and their stroke volume is 140ml (0.14L). 3

3. Calculate blood pressure, if Q = 5L/m, systolic R = 23, and diastolic R = 15. Also, classify which category this blood pressure reading falls into. 6

4. Calculate blood pressure if:Heart rate = 75 bpmStroke volume = 80ml (remember to convert to liters)Systolic R = 24Diastolic R = 16 Also, classify which category this blood pressure reading falls into. 8

QUESTIONS