HUMAN MEDICAL BIOLOGY, ANATOMY, PHYSIOLOGY AND PATHOLOGY - Y.I. Fedoniuk 2010

ANATOMY, PHYSIOLOGY, PATHOLOGY

CHAPTER 5. THE PROCESS OF BLOOD AND LYMPH CIRCULATION. ITS PATHOLOGY

PHYSIOLOGY OF BLOOD VESSELS

2. ARTERIAL BLOOD PRESSURE. MEASUREMENT METHODS

The magnitude of Blood pressure primarily depends on Cardiac Output and the resistance of The Vascular System to blood flow.

A distinction is made between systolic (maximum), diastolic (minimum), and pulse pressure.

During systole, blood is ejected by the left ventricle into the aorta; pressure rises and reaches its peak. This pressure is known as systolic pressure. In a middle-aged adult, it ranges from 110-125 mm Hg.

During diastole, arterial pressure drops sharply and is referred to as diastolic pressure. In healthy middle-aged individuals, diastolic pressure averages 60-80 mm Hg.

Pulse pressure is the difference between systolic and diastolic pressure. On average, it amounts to 35-50 mm Hg.

To measure arterial blood pressure, the method proposed by the Russian physician N.S. Korotkov is used (Fig. 5.39). This involves The Use of either a Riva-Rocci mercury sphygmomanometer or a mechanical tonometer.

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Fig. 5.39. Measuring blood pressure in humans

When measuring arterial pressure, the sphygmomanometer cuff is wrapped around the patient's arm above the elbow. Simultaneously, a stethoscope is placed over the antecubital fossa, where BLOOD FLOW IN the artery distal to the cuff can be auscultated. Until air is pumped into the cuff, blood flows silently through the artery, and no sounds are heard. Air is then pumped into the cuff, raising the pressure to a level sufficient to compress the artery and arrest blood flow within it. Air is slowly released from the cuff using a special valve. At the moment when the pressure in the artery falls slightly below the systolic arterial pressure level, blood surges through the compressed segment during systole. The impact of the blood pulse against the arterial wall in the compressed region generates a sound that the investigator auscultates below the cuff. At this moment, the height of the mercury Column in millimeters on the sphygmomanometer scale (or the digital reading on the tonometer display) is recorded and designated as the systolic pressure value.

To determine the diastolic pressure, air continues to be released from the cuff. At the moment when the pressure inside it drops slightly below the minimum blood pressure level, blood begins to flow in a continuous stream, and the sound disappears. The height of the mercury column corresponding to this point is then recorded as the diastolic pressure.