Study Questions Lab 3 Blood Pressure

Question 1

1. When you make a calibration curve of the aneroid manometer w/the mercury manometer, which variable is entered on the x-axis? Why?

Answer 1

• The aneroid manometer readings will be plotted on the X axis (INDEPENDENT) because the mercury manometer is dependent on what reading you set on the aneroid manometer because you set the aneroid manometer reading first, then read the mercury manometer reading.

Question 2

2. Over what range of pressures should you calibrate the aneroid manometer? Why?

Answer 2

Every 10mmHg, starting at 200mmHg and going down to 40mmHg. Cause we expect BP readings to range from 50-200mmHg for procedures in this week’s lab.

Question 3

3. Should you calibrate the aneroid manometer by starting @ high end of range and going down, or @ low end of range and going up? Why?

Answer 3

Starting at high end of range (200mg) and going down to lower end of range (40mm).

1) Prevent hysteresis: cause many instruments show slightly diff response as they’re raised thru their range compared w/being lowered thru their range.
2) Easier to inflate and let pressure out then inflate cuff by 10mmHg every calibration point

Question 4

4. If a person had poor hearing acuity (i.e. was “hard of hearing”) when they measure BP w/cuff and stethoscope, how would their readings compare w/actual measures of systolic and diastolic BP?

Answer 4

Underestimate systolic and overestimate diastolic

Question 5

5. What is the normal BP response to dynamic exercise? How does this differ from the response to isometric exercise? Explain the main physiological factors (at systems level, not a molecular level) in each case.

Answer 5

• Dynamic exercise: SP will raise while the diastolic pressure remains ~same.
• Body’s working muscles requires more O2. The rise in SP is due to the increase in HR and SV to increase CO, and inc contractility of the heart
• We have increased vasodilatory response in skeletal muscles and vasoconstriction of the splanchnic circulation and non-working muscles
• Since SP is the pressure exerted by the blood on the walls of the arteries during contraction of the heart it increases whereas DP pressure is during relaxation so there will be less of a change. Another factor is that DP is largely affected by TPR; during dynamic exercise there is a blood flow shift away from the gut and kidney (via vasoconstriction of arterioles to these organs) and toward the active working skeletal and cardiac muscle (via vasodilation) - the overall net effect reduces TPR. It is the decrease of TPR but the increase of CO that tends to cancel each other out and keep DP approximately constant.
  SUMMARY: The combo of inc contractility of the heart muscle and thus increased CO will inc SP, and the balance of a dec in TPR but inc in CO causes DP to remain constant.

ISOMETRIC:

• Both SP and DP inc
• Involves lower work rate than dynamic and the lower rate of nrg and O2 consumption means less inc in CO compared to dynamic. The inc in CO mostly due to inc in HR, little change in SV.
• TPR inc due to a lesser vasodilatory response in skeletal muscles and isometrically contracted muscles exert pressure on the blood vessels which partially or completely occludes them. Inc TPR causes both SP and DP to rise

Question 6

6. The Lab Manual describes 3 techniques which inc the loudness and clarity of the Korotkoff sounds. Name these, and describe briefly the way each one works.

Answer 6

All work by inc pressure gradient btwn artery under cuff and artery distal to cuff

1. Raise arm over head b4 inflating cuff
   - > Raising arm drains blood from forearm
2. Inflate cuff rapidly
   - > Avoids trapping too much blood in forearm (when cuff is inflated above venous closing pressure but below systolic BP, blood can enter arm but cannot leave it)
3. After cuff is inflated, squeeze first 8-10 times
   - > Vasodilates forearm, which inc capacity to accept blood

Question 7

7. How does using a pressure cuff which is too narrow affect the reading of systolic BP? Explain briefly.

Answer 7

If cuff too narrow, pressure pressing on artery will be lower than pressure in cuff. Results in OVERESTIMATION of actual BP.

Question 8

8. What is the expected effect on arterial BP of wrapping pressure cuff or tourniquet around a subject’s upper thigh (assume that the pressure exerted on the tissue is 200 mmHg)? Explain in physiological terms

Answer 8

• Reducing BF to one leg, you are inc the effective circulating volume of blood (volume of arterial blood effectively perfusing the tissue)
• More blood returns to the heart. As a result, there is an increase in mean systemic filling volume which increases right atrial volume and pressure.
• Via the Frank-Starling relationship you would get an increase in the contractile force of the heart therefore increasing the SV and therefore inc CO
• This would increase arterial BP
• By cutting off circulation to one leg, you are also increasing systemic vascular resistance, further increasing the arterial BP (b/c P = Q x R; therefore as R inc P inc)

Question 9

9. The arm is supposed to be supported at the level of the heart when taking BP readings. If the arm was raised above the heart, how would the BP reading be affected. Explain?

Answer 9

• Gravity affects BP by draining arm in blood. If arm above heart, BP is underestimated.
• Each cm that the cuff is located above the heart will reduce the blood pressure by 0.8mmHg/cm

Question 10

10. When measuring BP, after reaching the 5th Korotkoff sound, what should the measurer do?

Answer 10

After the 5th Korotkoff sound, the measurer should rapidly RELEASE all remaining PRESSURE in CUFF

Question 11

11. How can parallax error be avoided when reading aneroid manometer?

Answer 11

Placing it at any height for the observer to look at the needle on the pressure gauge straight on (not at angle)

Question 12

12. Give 2 examples of subconscious bias in BP measurement? How can such errors be minimized? Note: answer is NOT “be more aware of and try to avoid bias” give more concrete suggestions

Answer 12

1. If you know the patients history, whether they’re smokers, their age etc
   - > Avoid letting the experimenter know patient history
2. “Digit preference” for numbers ending with zero (is a tendency to guess participation by rounding estimates to values that end in zero or five) - allow another person with experience to read the manometer and tell you what pressure they saw
   - > Say aloud the exact value seen during the SP moment during Phase 1 of Korotkoff sounds to have a second experimenter write it down. Then do this again for DP as soon as Phase 5 comes around.

Question 13

13. Compare advantages and disadvantages of mercury sphygmomanometers versus aneroid sphygmomanometers, Why are aneroid manometers replacing mercury manometers in many clinical settings?

Answer 13

Mercury
Pro:
1. More accurate
2. Easier to maintain
3. Less likely to become decalibrated
Cons:
1. Risk of toxic effects from mercury spills
2. Contains liquid 

Aneroid
Pros:
1. No risk of toxic effects
2. WIde range of quality and price
Cons:
1. Require maintenance and recalibration every 6 months, should be handled gently to avoid decalibration

Aneroid manometers are replacing mercury manometers due to the risk of toxic effects from mercury spills

Question 14

14. Should aneroid sphygmomanometers be services on regular basis? Explain

Answer 14

• Yes require maintenance and recalibration every 6 months, should be handled gently to avoid decalibration.
• Contains no fluid, just air. Risk of air leaks.

Question 15

15. Explain how each of the 2 types of electronic BP devices works. Which one is more sensitive to movement?

Answer 15

2 types of electronic BP devices: oscillometric method and ausculatory method

Oscillometric:

• Based on interpretations of surges in pressure in the pressure cuff (does not use microphone). When the pressure in the cuff is greater than the pressure in the artery below the cuff, BF is occluded. The blood continues to recede and advance against the occluded artery in phase with contraction of the ventricles. The oscillations begin above systolic pressure and continue below diastolic so that systolic and diastolic pressures can only be estimated indirectly according to some derived algorithm.
• Oscillometric method is more sensitive to movement.

Ausculatory:
- Uses small microphone in the pressure cuff. Microphone needs 2 b centered over brachial artery for accurate readings. Small wire carries signal from microphone to microprocessor, which is programmed to “hear” Korotkoff sounds. Pressure reading @ time of appearance of tapping = SP, pressure @ time sound disappears = DP

Question 16

16. Should hypertensive patients be encouraged to use home electronic BP monitors? Explain

Answer 16

Yes, to avoid problems of white coat hypertension and masked hypertension.

2. White coat hypertension = phenomenon where a patient’s BP is elevated above normal values while in doctors office cause patient nervous and anxious.
3. MH = true hypertension is masked, where they have normal BP in the physician office but they have high BP during many other time periods of the day

Question 17

17. How do BP and HR respond to cold pressor test? Give a physiological explanation of the expected results.

Answer 17

• Both SP and DP and HR increased in response to the cold pressor test
  1. Stimulation of sensory afferent nerves due to painful stimulation of hand being in ice cold water which trigger activation of the SNS. This leads to inc NE levels which cause vasoconstriction of blood vessels and therefore increasing (TPR). Inc TPR would cause an inc in BP since MABP = TPR x CO
• More inter-subject variability in regards to HR. But likely due to an inc in sympathetic activity and dec in the vagal outflow

After hand is removed:

• Sympathetic stimulation (vasoconstriction) of limb is removed
• Subsequent progressive dec in HR and BP, returning these parameters to resting levels

Question 18

18. You need values for 3 things to calculate work rate on the Monark cycle ergometer. What are these?

Answer 18

WR is given in Watts. To calculate WR on the Monark it needs to be in kiloponds. We know 1 Watt = 6.12 kp*m/min; so to calculate work rate in kp we need:

1. Distance per revolution (6 m/rev)
2. The revolutions per minute the person is to be cycling at (60 rpm)
3. Conversion factor bwn Watt and kp (1 Watt = 6.12 kp*m/min)

Question 19

19. What are the expected changes in arterial BP and HR in a subject who has been lying quietly, then stands up rapidly? Explain in physiological terms.

Answer 19

1. There will be a transient dec in BP followed by an increase in HR to compensate for the dec in CO to bring the BP back to normal.
2. When the subject suddenly stands up, gravity will cause venous pooling to the legs.
3. This will lead to a dec VR and therefore dec CO
4. Baroreceptors sense drop in BP and trigger cardiopulmonary baroreflex to inc SNS stimulation so that we inc HR and cause arterial vasoconstriction. Since BP is proportional to CO and TPR, inc HR will increase CO.
5. Also get arterial vasoconstriction which will inc TPR which would also inc BP (MAP = CO x TRP)
6. This may over compensate and together in combo with skeletal pump bring to raise BP

Question 20

20. What are the problems in using manual ausculatory sphygmomanometry to measure exercise blood pressure?

Answer 20

1. There will be excess noise as well as movement artifacts that compromise the accuracy of the method.
2. The increase in noise associated with blood pressure measurement by manual sphygmomanometry during exercise masks the beginning of the Korotkoff sounds of systolic blood pressure causing an underestimation of SBP

Question 21

21. Which Korotkoff sound should be taken as systolic pressure? As diastolic presure?

Answer 21

1. Systolic- the beginning of the tapping noises (Phase 1)

2. Diastolic- the disappearance of the abrupt distinct muffling, soft blowing noise in phase 4 (Phase 5)

Question 22

22. If your hematocrit was inc by 10, what would happen to ur BP and why?

Answer 22

• BP would inc due to an inc in viscosity of the blood making the heart have to pump harder to maintain flow throughout the circulatory system. Viscosity would inc resistance and since P = QR, pressure would inc too.

Question 23

23. If you were an exercise physiologist, how would you answer the following questions if you were asked them by a sedentary 35-year old male w/a BP of 150/100?
    a) Do I have hypertension
    b) Why should I be concerned about my BP? How dangerous is hypertension to my health?
    c) Which BP measurement is more important – systolic or diastolic?
    d) What lifestyle modifications can I make in order to lower my BP and how effective are each of these modifications likely to be?
    e) Will I need to start taking drugs to lower my BP?

Answer 23

a) Do I have hypertension?
- Yes, stage 2 (>/160 OR >/100).

b) Why should I be concerned about my blood pressure? How dangerous is hypertension to my health?

High BP inc the risk of atherosclerosis (associated with MI and strokes) as well as other CVD. It’s very dangerous since it can lead to hypertrophy of the vascular walls (dec compliance and dec the radius of the vessels which increases BP further), can promote atherosclerosis and lead to an increased risk of stroke.

c) Which blood pressure measurement is more important-systolic or diastolic?
Systolic pressure.

d) What lifestyle modifications can I make in order to lower my blood pressure and how effective are each of these modifications likely to be?
1. Weight loss:
- Maintain normal body weigtht (BMI: 18.5 - 24.9 kg/m^2)
- likely as effective as medication
- 5-20mmHg per 10kg weight loss - up to 20
2. DASH eating plan - rich in fruits, vegetables, low fat dairy products w/reduced content of saturated and total fat
- 8-14mmHg dec
3. Decrease Sodium intake
4. Adult should achieve at least 150min of moderate physical activity per week, or 30 min/day most days of week
- 4-9mmHg up to 10
5. Decrease Alcohol intake limit of max 9 drinks a week for females and 14 drinks a week for males
- Shown to decrease BP by 2-4mmHg ~5

e) Will I need to start taking drugs to lower my blood pressure?
- Since you are in Stage 2 hypertension, recommended that you use two-drug combination e.g. thiazide-type diuretics that act to reduce your water retention paired with eACEI (angiotensin converting enzyme inhibitor) that acts to reduce functional ACE

Question 24

24. Describe current research evidence regarding the effectiveness of an exercise program for hypertensive subjects. Describe the optimal exercise program for hypertensive subjects.

Answer 24

Moderate intensity aerobic, dynamic resistance exercise, not enough evidence to isometric.

1. Aerobic training decreases resting and submax SBP, DBP and MAP.
2. Aerobic exercise has been shown to decrease SBP ~ 7 mmHg in hypertensive patients.
3. Canadian Society of Exercise Physiology (CSEP) recommends low to moderate aerobic exercises at an intensity of 50-70% of their maximum HR at least 30 mins a day for at least 4-5 days a week.

Question 25

25. Distinguish btwn prehypertension, Stage 1 hypertension, and Stage 2 hypertension

Answer 25

Normal: <120 AND <80
Prehypertension 120-139 OR 80-89
Stage 1: 140-159 OR 90-99
Stage 2: >/160 systolic BP OR >/100 DIASTOLIC

Question 26

26. List 5 major CV disease risk factors

Answer 26

1. Obesity
2. Diabetes mellitus
3. Sedentary lifestyle
4. Hypertension
5. Hyperlipidemia

Question 27

27. Describe in detail the proper procedures for measuring systolic and diastolic BP using an aneroid sphygmomanometer

Answer 27

1) Make sure you have a proper sized cuff (bladder should be 40% the circumference of the midpoint of the limb) and the length of the bladder should be twice that the width. Bladder should encircle 80% of the arm
2) Position the cuff so that the bladder is centered over the brachial artery.
3) Position the cuff so that the inferior margin is approx. 2 cm superior to the antecubital fossa.
4) Support the arm slightly flexed at the level of the heart.
5) Place the stethoscope over the brachial artery making sure for it not to touch the cuff, clothing or hoses, and it should be applied firmly but with as little pressure as possible
6) Close the thumb on the wheel on the bulb.
7) Inflate the cuff until the pressure is 30 mmHg above the point where the radial pulse disappears.
8) Deflate the cuff slowly, about 2-3 mmHg per second
9) Listen to the Korotkoff sounds through the stethoscope.
Phase 1 (Systolic): Clear tapping, gradually increases in intensity.
Phase 2: Deflate the cuff slowly and you should hear a murmur or swishing sound. Phase 3: Crisper sound which increases in intensity. Phase 4: Cuff pressure decreases more and sound changes to a distinct, abrupt muffling sound with a soft blowing quality.
Phase 5 (diastolic). Disappearance of sound.
10) Release all pressure in the cuff rapidly.
11) Wait for at least 1 minute before inflating the cuff again.

Question 28

28. What is “ambulatory BP” measurement, and what are its advantages compared to clinic BP measurement?

Answer 28

• Ambulatory BP monitoring measures BP at regular intervals. BP is measured during normal daily life using small digital BP machine that is attached to a belt around your body that’s connected to a cuff around your arm

With clinic BP measurement you may be subject to 2 types of problems:

1. White coat hypertension = an overestimation of BP because the patient is anxious or nervous from being in a physician office
2. Masked hypertension = the person’s true hypertension is masked, where they have normal BP in the physician office but they have high BP during many other time periods of the day