The indirect method of blood pressure measurement is divided into the Auscultatory method and the Oscillometric method.
The Auscultatory method has inherent drawbacks: First, there is an ongoing debate as to whether diastolic blood pressure corresponds to the fourth or the fifth phase, which results in a high degree of discrimination error. Secondly, by listening to the Koch's sound to determine the systolic and diastolic blood pressure, the readings are affected by a series of factors such as the doctor's mood, hearing, ambient noise, and the subject's nervousness, which is prone to introduce subjective errors and is difficult to standardize.
The electronic sphygmomanometer made by the principle of the auscultation method, although realizing automatic detection, has not yet completely solved its inherent shortcomings, namely, large error, poor repeatability, and easy to be interfered by noise.
The vast majority of blood pressure monitors and automatic electronic sphygmomanometers use the oscillometric method to measure blood pressure indirectly. The oscillometric method measures blood pressure by establishing the relationship between systolic, diastolic, and mean pressures and cuff pressure shock waves to discriminate blood pressure.
Because of the stable correlation between pulse pressure oscillations and blood pressure, the results of blood pressure measurement using the oscillometric principle are more accurate than those of the auscultation method in the application of actual home self-testing of blood pressure. And the oscillometric method of blood pressure measurement in the cuff without pickup device, simple operation, anti-external noise interference ability, but also can be measured at the same time the average pressure.
It must be pointed out that, from the principle of measurement, there is no question of which of the two profiles is more accurate.