Which medical device measures blood pressure non-invasively?

The sphygmomanometer is the device specifically designed to measure blood pressure in a non-invasive manner. This device typically consists of an inflatable cuff that is placed around the upper arm, which is connected to a pressure gauge. As the cuff inflates, it temporarily restricts blood flow in the brachial artery. Once the cuff is gradually deflated, the device measures the pressure in the artery through the sounds of the blood flow (Korotkoff sounds) or by reading the oscillations in the pressure gauge.

This non-invasive technique is widely used in clinical settings for routine blood pressure monitoring and is essential for diagnosing and managing hypertension. The sphygmomanometer is typically easy to use and does not involve any puncturing of the skin or insertion of instruments into the body, distinguishing it from invasive methods of measuring blood pressure.

While other devices listed may have their functions in medical diagnostics, they are not utilized primarily for measuring blood pressure non-invasively. The electrocardiogram records heart electrical activity, the ultrasonograph uses sound waves for imaging, and the plethysmograph measures changes in volume within the body, typically related to blood flow or other parameters, but not specifically blood pressure.