How Is Blood Pressure Tested?
The heart is a pump that works reliably for decades distributing thick oxygenated blood from the heart throughout the body. A blood pressure gauge is a simple way to measure the performance of the heart and blood vessels. To test your blood pressure you require a familiar device called a sphygmomanometer.
What is a Sphygmomanometer?
The medical term for a blood pressure measuring apparatus, the Sphygmomanometer is a healthcare device used to measure blood pressure. The Sphygmomanometer is derived from the Greek word sphygmós which means pulse and manometer which is the scientific term for pressure meter. Originally invented in 1881 by Samuel Siegfried Karl Ritter von Basch, the blood pressure monitor gained popularity in 1901 after Harvey Williams Cushing visited Italian physician Scipione Riva-Rocci and brought it back to America. Russian physician Nikolai Korotkov developed the modern sphygmomanometer after he discovered the “Korotkoff sounds” in 1905 at the Imperial Medical Academy in St. Petersburg.
The blood pressure monitor consists of four parts namely the cuff, pump, valve and measuring unit. The inflatable cuff wraps around the upper arm and is inflated to cut the blood flow. The inflation bulb or automatic inflation pump is used to inflate the cuff wrapped around the upper arm. The valve is used to deflate the arm cuff and allows blood to begin flowing again. The measuring unit such as a mercury, dial or digital manometer records the blood pressure reading. A stethoscope is also required to hear the blood rushing back through the arteries.
How Does a Sphygmomanometer Work?
There are two important numbers in a blood pressure reading. The peak pressure in the arteries during the cardiac cycle is known as the systolic pressure, and the lowest pressure is the diastolic pressure which is represented by the typical reading 120/80. When the cuff is inflated it exerts pressure that cuts the blood flow in the arm. The valve is used to deflate the cuff easing the pressure until the blood starts flowing. When the doctor hears the blood flowing through the brachial artery with a stethoscope the first measurement is taken (120), which is the maximum output pressure of the heart (systolic reading). Pressure is released until the Korotkoff sound stops completely and a second measurement is taken (80), which indicates the pressure in the system when the heart is relaxed (diastolic reading). Electronic blood pressure monitors automatically inflate and release the pressure and the device provides the blood pressure readings.
Each heartbeat squeezes blood through your arteries to organs and tissue before it returns to the lungs for re-oxygenation and then travels back to the heart. The systolic pressure represents the amount of pressure exerted on the arterial walls while the heart is beating. The diastolic pressure represents the amount of pressure exerted by the arterial walls against the blood in between heartbeats when the heart is relaxed. The readings are related to the flow or blood pressure that occurs from the beginning of one heartbeat to the beginning of the next which is called a cardiac cycle.