M 5.7- Measurement of Blood Pressure
What are normal blood pressure ranges?
1.) 80 +/- 10 mm of Hg. 2.) 120 +/- 10 mm of Hg.
What are the characteristics of blood as the diastolic value?
1.) Blood flow is noisy and turbulent. 2.) Blood flow is now continuous.
What are the characteristics of blood at this pressure?
1.) The blood flow is turbulent 2.) It creates a characteristic sound, the korotkoff (k-sound).
What is used to determine blood pressure?
A sphygmomanometer is used to determine blood pressure by studying the effect an external force has on the circulation system.
What are used to determine blood pressures over a series of days and useful in determining hypertension?
Ambulatory Blood Pressure Measurements (ABPMs)
By what value does the average blood pressure drop at night?
Approximately 20 mm of Hg.
Describe what happens from determining the systolic pressure to the diastolic pressure.
As the cuff pressure is reduced, the the artery remains open for longer periods of the cycle, but is still closed during the diastolic phase. The korotkoff sound can still be heard, but the periods of silence become less and less as the cuff pressure is released.The diastolic pressure is determined when the cuff pressure is released to a value that results in the artery being completely open, even during the diastolic phase.
At what stage of the cyclic cycle results in the lowest recorded pressure?
At diastole, which occurs following relaxation of the heart.
At what stage of the cyclic cycle will the highest blood pressure be recorded?
At systole, which results from maximum contraction of the heart.
How is arterial blood pressure normally expressed and what is the normal value?
It is normally expressed as the ratio of systolic and diastolic pressure- normal blood pressure is 120/80 mm of Hg.
In a graphical representation of the cyclic cycle, what is the reason behind the abnormal increase of pressure following ventricular systole?
The abnormal increase in pressure is due to the closing of the semi lunar valves following ventricular systole, which causes a back swell of blood and increase in pressure.
What is the result of the heart pumping blood in a rhythmic fashion?
The blood pressure within arteries will be cyclic.
Describe the mechanism of how the cuff works in determining systolic pressure.
The cuff in inflated above systolic pressure so as to compress the artery, so that no blood can flow through it. This can be verified using a stethoscope. The cuff pressure is then slowly released until just below systolic pressure, at this point the vessel will only open at peak systolic pressure and allow spurts of blood through. This pressure is referred to as systolic pressure and in a healthy individual is roughly 120mm of Hg.
Where and why is the cuff placed?
The inflatable cuff is placed around the upper arm, roughly at the same level as the heart. It is placed over the brachial artery, as it lies superior to only one bone and hence is easily compressed.
What are the main components of a manometer and what is used in conjunction with it?
The main components of a manometer are, the inflatable cuff and the hand pump used to inflate the cuff. A stethoscope is used in conjunction with the sphygmomanometer.
What is an important parameter for defining abnormal blood pressure, and how is it determined?
The pulse pressure, and is the difference between systolic and diastolic pressure.
How can older people be diagnosed as having hypertension?
They have high systolic blood pressure values, which are determined using ambulatory blood pressure measurements. Their arteries loose their elastic properties and hence become rigid meaning when blood is pumped during the systolic cycle the vessel doesn't expand as much hence the blood is in a reduced volume and therefore pressure increases.
