Oscillometric measurement devices

Oscillometric measurement devices use an electronic pressure sensor with a numerical readout of blood pressure. In most cases the cuff is inflated and released by an electrically operated pump and valve, which may be fitted on the wrist (elevated to heart height), although the upper arm is preferred. Initially the cuff is inflated to a pressure in excess of the systolic arterial pressure, and then the pressure reduces to below diastolic pressure. Once the blood flow is present, but restricted, the cuff pressure will vary periodically in synchrony with the cyclic expansion and contraction of the brachial artery. The values of systolic and diastolic pressure are computed from the raw data, using an algorithm.

 

Full-automatic blood pressure monitors

Oscillometric measurement device

The blood pressure measurement using so-called oscillometric devices works similiar like the auscultatoric method. Instead of recording the readings acoustically the oscillometric method records and evaluates the oscillations of the arteries. Those oscillations have a very typical curve. The oscillations occur when the blood flow first is interrupted and than starts flowing again. They become stronger, than diminish until they disappear when the blood starts flowing normally.
Both the systolic and diastolic value is calculated with the help of an algorithm. The calculated values are than visualized on the display.

 

Semi-automatic blood pressure monitors

Oscillometric measurement device

When using semi-automatic blood pressure monitors for measuring blood pressure the cuff is inflated by hand using a pumping ball. The device deflates automatically. Beyond this the blood pressure is evaluated and calculated the same way as it is done by full-automatic devices.