The instruments to measure it and how they change
The question
How is blood pressure measured and what innovations should we expect in the age of technology?
Answer: Measuring blood pressure is an essential part of understanding its meaning and clinical implications. The reliability of blood pressure values, their reproducibility over time and, above all, the quality of clinical and therapeutic decisions taken in response to changes in blood pressure values depend on the more or less correct measurement. The first experiment in the direct measurement of blood pressure is traced back to the Reverend Stephen Hales, who in 1733 inserted a glass tube into an artery of his own horse and noticed that the blood inside it rose to a much higher level than that of the heart, ruling out the possibility that this could occur simply passively. However, the epoch-making breakthrough in terms of blood pressure measurement was the one introduced by an ingenious Italian scientist, Scipione Riva-Rocci, who on 10 December 1896 published the results of his research into the characteristics of an ingenious new instrument for measuring blood pressure called a 'sphygmomanometer' in the Gazzetta Medica of Turin, which could measure blood pressure in a relatively simple and bloodless manner (without having to sacrifice any pets, in other words).
The discovery of the sphygmomanometer started the spread of the concept of blood pressure as we understand it today. The principles underlying the instrumentation developed by Riva-Rocci are today the cornerstone of the development and diffusion of easy-to-use instruments with which almost anyone is today able to know what their blood pressure values are. Over time, the instruments used to measure blood pressure have progressively evolved, giving rise to a dual technological realisation embodied on the one hand in the mercury column or aneroid instruments, which base their measurement on reading the value by means of a pointer and a dial similar to that of a chronometer which, instead of the hours, shows the possible pressure values. Today, mercury instruments have been banned precisely because of the content of the liquid metal, which is rightly considered dangerous and polluting, while aneroid instruments have remained the prerogative almost exclusively of sanitary practitioners and a few romantics fond of the history of blood pressure measurement. Today, the world of blood pressure monitors is largely dominated by automatic instruments that measure blood pressure autonomously by inflating and deflating a cuff that can easily be positioned at arm level and that show the values taken on a large display from which anyone can conveniently read them. This procedure can, of course, be repeated wherever one wishes, on whomever one sees fit, as many times as one wishes, at more or less regular intervals and at any time of the day, both in conditions of well-being and when unusual symptoms develop that could depend on poor blood pressure control. The same basic principle is applied to portable instruments used for ambulatory monitoring of 24-hour blood pressure (ABPM) what is erroneously referred to as 'Holter pressure' without remembering that Holter was the personal surname of a brilliant scientist who invented the continuous and bloodless method of assessing the electrocardiographic trace and this method has nothing to do with ambulatory blood pressure measurement.
The importance of blood pressure measurement, however, has meant that research into instruments for measuring it is progressing very rapidly, and the next stage will be the development of reliable instruments capable of measuring blood pressure without the aid of a sphygmomanometer (so-called cuffless), capable of interpreting the characteristics of the pulse wave, and which will probably be applied and disseminated through systems similar to apps and usable through smartphones, smartwatches or other similar dedicated instruments. Today, looking at the net, it is possible to find a number of apps for sale that promise pressure measurement through these types of instruments and methods, but their reliability is still very limited if not non-existent and in many cases they are more like toys.