BLOOD PRESSURE 12/3/2012 SHMD 139
Blood Pressure Pg 34 • Blood 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
Blood Pressure Pg 34 • Typical BP for the average person: 120Systolic: When the heart is contracting 80 Diastolic: When the heart is relaxing • BP unit of measurement: milligrams of mercury (mmHg)
Calculating Blood Pressure Pg 33 • Cardiac 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)
Calculating Blood Pressure Pg 34 • Cardiac 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
Calculating Blood Pressure Pg 34 • Blood Pressure (mmHg) = Cardiac Output (litres per minute) x Resistance to flow (R) • Thus, BP = Q x R • Resistance to blood flow is caused by: • Size of the blood vessels. i.e. The smaller the blood vessel, the greater the resistance • Thickness of the blood. i.e. The thicker the blood, the greater the resistance.
Calculating Blood Pressure • If heart rate = 72 bpm • & stroke volume = 85ml • Cardiac output? • 85ml ÷ 1000 = 0.085L • Thus, • 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
BLOOD PRESSURE & exercise Pg 34 • Exercise 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
Hypertension Pg 132 • Is 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 .
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 MANOEUVRE Pg 36 • The 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.
measuring BLOOD PRESSURE Pg 167 • It 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.
measuring BLOOD PRESSURE Pg 167 • The client should be seated and relaxed for 5 minutes • 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. • Find the brachial pulse – it should be on the inner side of the arm, just under the biceps muscle. • 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. • Place the earpieces of the stethoscope in your ears and place the microphone over the brachial pulse.
measuring BLOOD PRESSURE Pg 167 • Inflate the cuff up to 200mmHg. • Slowly open the valve by turning it anti-clockwise and release the pressure. • 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. • Keep deflating the cuff, and when the heart beat becomes muffled or disappears, this is your diastolic reading. • Keep deflating the cuff and, if necessary, repeat after around 30 seconds.
QUESTIONS • Define: • Blood pressure. 2 • Cardiac output. 2 • Stroke volume. 2 • Hypertension. 2 • What do the following abbreviations stand for: • BP. 2 • Q. 2 • SV. 2 • Differentiate between ‘systolic’ and ‘diastolic’ blood pressure. 2 • Provide the unit of measurement for: • Blood pressure. 1 • Cardiac output. 1 • Stroke volume. 1
QUESTIONS • Provide the average stroke volume of a person at rest? 2 • Does stroke volume ever change? If so, when? 2 • Provide the average value of cardiac output at rest, as well as during exercise. 2 • List and briefly explain the 2 factors that cause resistance to blood flow. 4 • How does exercise affect blood pressure? 5 • What are the implications of a high BP? 2 • Explain: • The valsalva manoeuvre. 3 • Who uses it, 2 • And why. 2
QUESTIONS • Should someone with a high BP perform the valsalva maneuver? Why/why not? 3 • Which two instruments are used to measure BP? 2 • Why is it important to measure BP before an individual performs exercise testing? 3 • Explain the procedure for measuring blood pressure. 10 • In tabular form, write down the norms for blood pressure. 16
QUESTIONS Calculate: • 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 • 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 • 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 • Calculate blood pressure if: • Heart rate = 75 bpm • Stroke volume = 80ml (remember to convert to liters) • Systolic R = 24 • Diastolic R = 16 • Also, classify which category this blood pressure reading falls into. 8