The error of the electronic sphygmomanometer is the electronic scanning, such as in the measurement process, respiratory pause, or attention to be attracted, will cause the error called blood pressure, this point can be ignored. Mercury sphygmomanometer error is caused by human beings, the degree of its accuracy depends on the degree of speed and the degree of response of the measurer, so to speak, for the mercury sphygmomanometer error value, the measurer 0.1 seconds of pause, at least can be caused by the difference of 5 numbers (for the absolute blood pressure in the laboratory). Nowadays, the error of most of the measurers is in the range of 10 to 15 values.
Now many consumers feel that electronic sphygmomanometers measure blood pressure inaccurately, in response to this problem, I as a sales of medical equipment for a number of years of the old staff, can give you an explanation. We all know that to measure the more accurate blood pressure, in the measurement of the mood must be calmed down, because emotional fluctuations on the blood pressure is very big, may cause before and after the value of the two times the difference is relatively large, can be poor to 50mmHG or so, in addition to the blood pressure in the middle of the day is also unstable, in general, the morning blood pressure value than the afternoon to be lower. And blood pressure is fluctuating, that is why the electronic blood pressure monitor in two consecutive measurements show different values of the reason, of course, this value will not be very large, generally within 10 digits. Also, electronic sphygmomanometer measurement, cuff (and wrist) position can not be too much difference, that is also the cause of a relatively large error, electronic sphygmomanometer instructions written on the location of a very clear, and accompanied by pictures.
Mercury sphygmomanometer readings are an approximate value, depending on the degree of care, in the mercury sphygmomanometer scale, 10 values less than 1CM away from the distance will be ignored, which is why the mercury sphygmomanometer in the successive measurements, there will be the same value.
In hospitals, the sphygmomanometers used by doctors are mercury sphygmomanometers because of the small investment and lack of consumption. Electronic sphygmomanometers are more expensive to buy than mercury ones and consume electricity or batteries during use, which is a costly expense for hospitals (whose profits are considerable).
If anyone doubts the accuracy of the electronic sphygmomanometer, I can tell you a way to compare, with a stethoscope tee tube, the electronic sphygmomanometer and mercury sphygmomanometer connected together, a cuff, two sphygmomanometers, the measured person to watch the electronic screen, the measured person to read the value of the mercury sphygmomanometer on the scale, the difference between the general in the five numbers. I often give customers to compare, or have some experience.