Ex 30: Blood Pressure & Pulse Determinations

Objectives:

1. To define systole, diastole, and cardiac cycle.
2. To state the normal length of the cardiac cycle, the relative pressure changes occurring within the atria and ventricles during the cycle, and the timing of valve closure.
3. To use the stethoscope to auscultate heart sounds and to relate heart sounds to the cardiac cycle events.
4. To describe the clinical significance of heart sounds.
5. To demonstrate the thoracic locations where the first and second heart sounds are most accurately auscultated.
6. To define murmur.
7. To define pulse, pulse deficit, blood pressure and sounds of Korotkoff.
8. To accurately determine the apical and radial pulse of a subject.
9. To accurately determine the blood pressure of a subject by using a sphygmomanometer, and to relate systolic and diastolic pressures to events of the cardiac cycle.
10. To note factors affecting and/or determine blood pressure and skin color.

Hypotheses & Procedures
Part 1: Cardiac Cycle : Auscultation of heart sounds
     If students listen with a stethoscope then they will be able to determine the normal length of the cardiac cycle, use a stethoscope to ausculatate heart sounds, relate heart sounds to the cardiac cycle, describe the clinical significance of heart sounds, demonstrate thoracic locations where the first and second heart sounds are most accurately heard, and define murmur.

Part 2: Cardiac Cycle: Palpation of the Pulse
      If students palpate their pulse points, then they will be able to define pulse, and pulse deficit and accurately determine the apical and radial pulse of a subject, define pulse, pulse pressure.

Part 3 Blood Pressure Determinations
     If students use a sphygmomanometer then they will be able to determine the blood pressure of a subject by using a sphygmomanometer, and to relate systolic and diastolic pressures to events of the cardiac cycle, define blood pressure and the sounds of Korotkoff, and describe the effect of posture, exercise and a noxious sensory stimulus on blood pressure.

Part 4: Skin Color as an Indicator of Local Circulatory Dynamics
     If students obstruct venous return by inflating the sphygmomanometer cuff and observe the arm, then they can observe the effect of the lack of oxygen on  skin color.  When the cuff pressure is released, then students can observe the effect on accumulation of metabolic wastes on blood flow and its impact on skin color by comparing the cuffed forearm color with an uncuffed arm color.

     If students use a sphygmomanometer to obstruct arterial supply by inflating a sphygmomanometer to a raised arm with a clenched fist, then they can observe the impact of ischemia to skin color by comparing it to the uncuffed, unraised arm.

     If students use a sphygmomanometer at a low level of pressure for 5 minutes, then they can observe the subjective and objective effects of venous congestion by comparing the cuffed and uncuffed arms.

     If students hold one arm over their head and let the other hand hang at their side for 1 minute, then they can observe the effect of impaired blood flow to skin color by comparing the two arms.

     If students block blood flow first through both the radial and and the ulnar artery, and compared to blocking blood flow only of the radial artery they can observe the impact of collateral blood vessels.

     If students lightly and more firmly scratch the skin of a forearm then they can observe a wheal and flare result of injured tissues.


Materials (on lab sheet)


Experiment/Data and lab questions

Part 1: Cardiac Cycle : Auscultation of heart sounds

 1.    Insert a picture of you and your partner using the stethoscope to listen to heart sounds. Within your caption, also identify the source of the "lub" and the "dup" sounds that you heard.

Questions to answer:  

3. Approximately how much time passes between the "dup" and the following "lub" sound?:  ______ sec  = time from the end of one cardiac cycle to the beginning of the next

4. How does this interval compare to the time interval between the "lub" and the "dup" of a single heartbeat?

5. Use the following diagram of the cardiac cycle to describe what's going on in the heart at each sound.

6. What is a heart murmur?

Part 2: Cardiac Cycle: Palpation of the Pulse.

1.       Insert a picture of you and your partner palpating pulse.  Label your picture with a caption describing the pulse point that you are using in this picture, and define what a pulse point is.

Questions to answer:

2. What was your partner's average resting pulse rate/min?

3. Explain why apical heart rate/minute may be greater than pulse/min.  

4. What is pulse deficit, and what can it indicate?

Part 3 Blood Pressure Determinations

1. Insert a picture of you and your partner using the Vernier LabQuest and sphygmomanometer to measure blood pressure.  

2. Insert a picture of your data, labelled with the systolic and diastolic pressure. 

3. Show your calculations for pulse pressure and for Mean Arterial Pressure.

4. Explain how the Valsalva maneuver affects venous pressure.

5. What was the effect of posture on blood pressure (compare blood pressure sitting vs reclining)? 

6. What was the effect of exercise on blood pressure compared to sitting?

7. What was the effect of a noxious sensory stimulus (cold) on blood pressure compared to sitting?

8. Which of the following factors probably had the greatest influence change in blood pressure for each (posture, exercise, noxious sensory stimulus? 

Cardiac Output (CO) = change in P (pressure) / R (resistance)

Resistance, often called peripheral resistance, is affected by the length of a vessel, vasodilation/vasoconstriction and elasticity of the blood vessels. 

Cardiac Output (CO) = Stroke Volume (SV) x Heart Rate (HR)

Stroke Volume is affected by:

a. venous return (how much blood dribbles into the heart from the veins), which is in turn affected by exercise, heart rate and respiratory rate

b. contractility of the heart muscle (stretched fibers contract harder and eject more blood)

Heart Rate (HR) is affected by the medulla, which is influenced by blood pressure

Part 4: Skin Color as an Indicator of Local Circulatory Dynamics

Questions: 

1. What was the effect of an accumulation of metabolites and depletion of oxygen on skin color?

2. What was the effect of vasodilation and flushing of local metabolites on skin color?

3. What was the effect of completely removing blood flow on skin color?

4. What was the effect of venous congestion on the color of the blood visible through the nail beds?

5. What is the benefit of collateral blood flow?

6. What is the cause of a wheal and flare response?

Conclusion

1. Define systole, diastole, and cardiac cycle.
2. What is the cardiac cycle?
3. At which points in the cardiac cycle are heart sounds heard?
4. Which part of the cardiac cycle contributes to systolic blood pressure?
5. Which part of the cardiac cycle contributes to diastolic blood pressure?
6. Define each of the following terms and describe the effect of exercise, posture and noxious sensory stimulation on each.
1. cardiac output
2. heart rate
3. stroke volume
4. peripheral resistance
5. vasoconstriction/vasodilation

1. What do the following skin colors indicate about the circulatory system:
1. white/pallor
2. blue/purple
3. red