24.12:
Measurement of Blood Pressure
Blood pressure is commonly measured in the brachial artery of the left arm using a sphygmomanometer. It includes a rubber cuff, a rubber bulb for inflating the cuff, and a meter that records the cuff pressure.
First, the cuff is wrapped around the arm, just above the elbow, and inflated. This pressure, approximately 30 mm Hg above the typical systolic pressure, temporarily stops the blood flow in the brachial artery.
A stethoscope is then placed below the cuff on the brachial artery, and the cuff is slowly deflated. This opens the artery to let a blood spurt pass through, creating an audible sound detected in the stethoscope.
The pressure measured at this first audible sound corresponds to the systolic blood pressure.
Further deflation of the cuff causes the sounds to become faint until they are inaudible. The pressure measured at this point is the diastolic blood pressure.
These sounds heard during blood pressure measurement are known as Korotkoff sounds.
The difference between systolic and diastolic pressure, known as pulse pressure, usually around 40 mm Hg, is also clinically significant.
24.12:
Measurement of Blood Pressure
Assessing blood pressure is a standard procedure executed in virtually all medical environments. The method utilized today was established over a hundred years ago by an innovative Russian doctor, Dr. Nikolai Korotkoff. The soft ticking noise, known as Korotkoff sounds, heard while taking blood pressure readings results from turbulent blood flow within the vessels. The apparatus required for this procedure includes a sphygmomanometer, a blood pressure cuff attached to a gauge, and a stethoscope. Here is a step-by-step guide to the technique:
The healthcare provider securely fastens an inflatable cuff around the patient's arm at the brachial artery. The cuff should be fastened an inch above where the pulse is felt.
The provider then uses a rubber bulb to pump air into the cuff, increasing pressure around the artery until blood flow into the patient's arm ceases momentarily.
The stethoscope is placed on the patient's antecubital area, and as the air in the cuff is slowly discharged, the provider listens for the Korotkoff sounds.
Of the five recognized Korotkoff sounds, only the first and the last are typically recorded. No sounds are initially heard as the vessels have no blood flow, but as the cuff pressure lessens, blood flow resumes to the arm. The first Korotkoff sound signifies systolic pressure. As the cuff continues to deflate, blood can freely circulate through the brachial artery, and all sounds cease. The last sound heard is noted as the patient's diastolic pressure.
Many medical facilities use automated machines for blood pressure measurements based on the same principles. A more recent development is a compact device that clasps around the patient's radial artery at the wrist. The patient raises their wrist to the heart level while the instrument measures blood flow and records pressure.
Blood pressure measurements offer crucial insights into a patient's cardiovascular health. Hypertension, or high blood pressure, is one common condition detected through these measurements. Persistent hypertension can lead to severe health complications, including heart disease and stroke. On the other hand, hypotension, or low blood pressure, while less common, can indicate issues such as cardiac issues, endocrine issues, or severe infection. It can lead to dizziness, fainting, and, in extreme cases, can be life-threatening. Another clinically significant condition is pulsus paradoxus, an exaggerated drop in blood pressure during the inspiratory phase of respiration. This condition is often associated with severe asthma, cardiac tamponade, and constrictive pericarditis. Accurate blood pressure measurements are vital in the early detection and management of these conditions.