When measuring arterial blood pressure, the first Korotkoff sound occurs when the cuff pressure is about the same as the pressure in the brachial artery and a small amount of blood passes through the brachial artery. The pressure indicated in the pressure gauge at this moment represents the ____ pressure. ? systolic ? diastolic ? average
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Step 1: The first Korotkoff sound occurs when the cuff pressure is about the same as the pressure in the brachial artery. Show more…
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Systolic blood pressure The blood pressure cuff is placed on the upper arm and inflated to stop blood flow from the brachial artery to the arm. When the pressure in the cuff exceeds the pressure in the artery, blood flow is occluded and no pulse will be felt below the cuff. As you slowly release the pressure cuff, the pressure begins to decrease. When it reaches the peak systolic pressure, the artery opens a little but the flow is turbulent rather than laminar. This generates tapping sounds called Korotkoff sounds, which can be heard through a stethoscope. When turbulent blood flow is first heard, the cuff pressure approximates systolic pressure. Diastolic blood pressure As the cuff pressure continues to decrease and the artery regains its normal diameter, blood flow becomes laminar and the sounds become muffled and then disappear. The cuff pressure at the point of the sound muffling approximates the minimum blood pressure (diastolic pressure). However, the disappearance of sound is commonly used to determine diastolic pressure as it is easier to detect than muffling sounds. This is acceptable since the two occur within a few millimeters of mercury. Note that in some healthy people, sounds can be heard at pressures appreciably below the true diastolic pressure. In these people, it is not possible to define their diastolic pressure accurately.
Sri K.
Q1: Define the first and second sounds of Korotkoff. Which sound is used to approximate systolic pressure and which sound is used to approximate diastolic pressure? Q2. Note the difference in systolic pressure value between when (a) the sound actually began, (b) was detected by the stethoscope transducer, and (c) was recorded, and the time when the observer first heard the sound and pressed the event marker keystroke. (Example: 141 mmHg – 135 mmHg = 6 mmHg.) What factors could account for this Q3. Do both systolic and/or diastolic pressure change as your heart rate increases? Q4. How does this change affect your pulse pressure?
Adi S.
1. Note the difference in systolic pressure value between when (a) the sound actually began, (b) was detected by the stethoscope transducer, and (c) was recorded, and the time when the observer first heard the sound and pressed the event marker keystroke. (Example: 141 mmHg – 135 mmHg = 6 mmHg.) What factors could account for this difference? Would the observed difference be the same if measured by another observer? Explain your answer. 2. Do both systolic and/or diastolic pressure change as your heart rate increases? 3. How does this change affect your pulse pressure? 4. Define the first and second sounds of Korotkoff. Which sound is used to approximate systolic pressure and which sound is used to approximate diastolic pressure?
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