MEDICAL INNOVATIONS

BLOOD PRESSURE MACHINE:
(BP machine)

The first recorded instance of the measurement of blood pressure was in 1733 by the Reverend Stephen Hales. Hales took a horse and inserted a brass pipe into an artery. This brass pipe was connected to a glass tube. Hales observed the blood in the pipe rising and concluded that this must be due to a pressure in the blood.

Carl Ludwing recorded human blood pressure for the first time in 1847. Ludwing's kymograph chad catheters that were inserted directly into the artery. His kymograph consisted of a U-shaped manometer tube connected to a brass pipe cannula into the artery. The manometer tube had an ivory float onto which a rod with a quill was attached. This quill would sketch onto a rotating drum hence the name 'Kymograph' or 'wave writer' in Greek. However, this method was also invasive. By the nineteenth century, scientists began to experiment with various devices to measure the amplitude of the pulse wave. Vierordt was the first to use an inflatable cuff around the arm to constrict the artery.

in 1881, samuel Siegrfried Karl Ritter von Basch invented the sphygmomanometer. His device consisted of a water-filld bag connected to a manometer. The manometer was used to determine the pressure required to obliterate the arterial pulse. However, the modern era of blood pressure measurement started with the introduction of the sphygmomanometer by Scipione Riva-Rocci in 1896. He created an inflatable rubber cuff designed to obstruct the blood flow of the brachial artery. A column of mercury was used to quantify the pressure requi9red to inflate a rubber cuff at the moment the pulse became unpalpable distal to the cuff. Although revolutionary, Riva-Rocci's invention was limited by inherent problems; specifically, his cuff was too narrow, resulting in inaccurate measurements. Von Recklinghausd later recognized this error and widened the cuff 5 to 13 cm.

Riva-Rocci's sphygmonanometer was spotted by the American neurosurgeon Harvery Cushing while he was traveling through Italy. Seeing the Potential benefit he returned to the US with the design in 1901. After the design was modified for more clinical use, the sphygmomanometer became commonplace.

Nikolai Koratfoff was the first to observe the sounds made by the constriction of the artery in 1905. Korotkoff found that there were characteristic sounds of certain points in the inflation and deflation of the cuff. These Korotdoff sounds were caused by the abnormal passage of blood through the artery, corresponding to the systolic and diastolic blood pressures. A crucial difference in Korotdaff's technique was the use of the stethoscope to listen for sounds of blood flowing through the artery. This method proved to be more reliable than the previous palpitation techniques and thus became the standard practice. Over the years the sphygmomanometer has evolved considerably.

Mercury manometer is considered to be the "Gold Standard" of measurement because it does not go out of calibration. However, mercury sphygmomanometer is likely to be banned from clinical use because of the danger of toxicity. Accurate, automated devices are available to replace the mercury sphygmomanometer. Aneroid and electronic instruments have some advantages of portability and ease of use. Most manufactures of aneroid and electronic instruments recommend calibration against a mercury manometer every six months.

Blood pressure is measured in millimeters of mercury (mm of Hg) and recorded as two numbers - systolic pressure "over" diastolic pressure.