BPK 142 Study Guide - Final Guide: Brachial Artery, Korotkoff Sounds, Stethoscope
27 Apr 2018
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BPK 142 - LABORATORY REVIEW QUESTIONS - PART 2 (Week 9)
Laboratory #9 – Cardiovascular Responses to Submaximal Exercise
1. Describe the step by step procedure for measuring blood pressure.
- Subject seated, resting for at least 5 mins
- Choose child/adult (< 25 cm = child cuff)
- Wrap deflated cuff around subject’s upper arm w/ lower margin of cuff about 1 inch
above elbow joint. Arrow on cuff pointed to brachial artery.
- Attach manometer to cuff using clip.
- Locate brachial artery and put stethoscope over it.
- Ensure exhaust valve is closed. Turn the knurled screw clockwise until snug.
- Pump bag to 30 mm Hg pressure above point at which radial pulse disappears (~ 100
mm Hg or over).
- Release at rate of 2-3 mm Hg/second (no steps heard)
- When you hear sound at rhythm of heart contraction = systolic pressure.
- Disappearance of sound = diastolic pressure
2. When measuring blood pressure you must listen for Korotkoff sounds at the brachial
artery using a stethoscope. Why can't you hear these sounds before the cuff is inflated?
- When the cuff is inflated the brachial artery in constricted and the blood flow through the
lower arm is turbulent.
- This turbulent blood flow causes the walls of the artery underneath the stethoscope to
vibrate. It is these vibrations that cause the Korotkoff sounds heard in the stethoscope.
- Before the cuff is inflated, the brachial artery is no longer constricted and the blood flow
becomes laminar with no turbulence.
3. If blood pressure was measured at the level of a subject's calf rather than at the level
of the upper arm, would you expect the blood pressure readings to be different? Explain.
- You would expect the reading to be higher. This is because since calf is further away
from the heart than the arm, meaning it would need to pump blood at a greater pressure
for it to reach the calf than the arm.
- The pull of gravity causes more blood to stay in the lower extremities, so there’s higher
pressure in the legs.
- The vessels in the legs are also narrower which contributes to a higher reading.
4. Describe four sources of error when recording blood pressure from an exercising
subject.
- Diastolic pressure is difficult to measure as there are still noises below the actual
pressure cause by the high velocity of blood flow.
- Stethoscope is hard to keep on an exercising subject.
- Any noises that the exercising subject makes can make it difficult to hear noise through
stethoscope.
- Posture can affect blood pressure. Subject should be relaxed, sitting with their back
supported and legs uncrossed.
Document Summary
Bpk 142 - laboratory review questions - part 2 (week 9) Laboratory #9 cardiovascular responses to submaximal exercise: describe the step by step procedure for measuring blood pressure. Subject seated, resting for at least 5 mins. Choose child/adult (< 25 cm = child cuff) Wrap deflated cuff around subject"s upper arm w/ lower margin of cuff about 1 inch above elbow joint. Locate brachial artery and put stethoscope over it. Pump bag to 30 mm hg pressure above point at which radial pulse disappears (~ 100 mm hg or over). Release at rate of 2-3 mm hg/second (no steps heard) When you hear sound at rhythm of heart contraction = systolic pressure. Disappearance of sound = diastolic pressure: when measuring blood pressure you must listen for korotkoff sounds at the brachial artery using a stethoscope. When the cuff is inflated the brachial artery in constricted and the blood flow through the lower arm is turbulent.
