Measurements of Blood Pressure :)

Wow, these are challenging, for (1)

The Korotkoff sounds are produced by vibrations of the arterial wall induced by the high frequency components of the pressure wave. We often listen for the first Korotkoff sound.

2. Are the blood pressure measurements different when they were taken in the standard sitting position, reclining and standing up? Explain what might have caused any differences observed.

Blood pressure measurement is most commonly made in either the sitting or the supine position, but the 2 positions give different measurements. It is widely accepted that diastolic pressure measured while sitting is higher than when measured supine (by 5 mm Hg), although there is less agreement about systolic pressure. When the arm position is meticulously adjusted so that the cuff is at the level of the right atrium in both positions, the systolic pressure has been reported to be 8 mm Hg higher in the supine than the upright position.

Other considerations include the position of the back and legs. If the back is not supported (as when the patient is seated on an examination table as opposed to a chair), the diastolic pressure may be increased by 6 mm Hg. Crossing the legs may raise systolic pressure by 2 to 8 mm Hg.

In the supine position, the right atrium is approximately halfway between the bed and the level of the sternum; thus, if the arm is resting on the bed, it will be below heart level. For this reason, when measurements are taken in the supine position the arm should be supported with a pillow. In the sitting position, the right atrium level is the midpoint of the sternum or the fourth intercostal space.

Pulse pressure is directly related to arterial pressure, assuming constant diameter and compliance. This will increase venous return, bringing up the frank-starling relationship. Basically increased venous return to the heart will cause greater contractility and result in an increase in stroke volume.

The Frank-Starling effect describes the effect whereby greater filling of the ventricles results in a greater ventricular contraction. It allows the ventricles, effectively, to ʺautoregulateʺ stroke volume, so that it can pump effectively. It allows the heart to automatically compensate for increases in the amount of blood returning to the heart. If the Frank-Starling effect didnʹt exist, and the stroke volume of the heart was always constant, then in a situation in which venous return is increased, there would be ʺleftoverʺ blood in the heart after each contraction. This extra blood would build up over time, increasing in volume, until the heart was so distended that contraction would be ineffective.

It would help to tell us your textbook ... What is it?

Systolic blood pressure is determined by the onset of the auscultated pulsation or first Korotkoff sound. The disappearance of Korotkoff sounds or fifth Korotkoff sound (K5, the last sound heard) is the definition of diastolic pressure in adults. In children, particularly preadolescents, a difference of several millimeters of mercury is frequently present between the fourth and fifth Korotkoff sounds. In some children, the Korotkoff sounds can be heard to 0 mm Hg, which has limited physiological meaning.

- Pulse Pressure is 142 - 92 = 50

- At normal resting heart rates, MAP can be approximated by the following equation:

Mean arterial pressure = Pdias + 1/3 (Psys - Pdias)

For example, if systolic pressure is 120 mmHg and diastolic pressure is 80 mmHg, then the mean arterial pressure is approximately 93 mmHg using this calculation.

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