Which instrument is commonly used to measure a patient's blood pressure?

The sphygmomanometer is specifically designed to measure blood pressure, making it the correct choice for this question. It typically consists of an inflatable cuff that wraps around the patient's arm and can either be analog or digital in its reading mechanism. This device works by temporarily stopping blood flow in the artery and then gradually releasing the pressure, allowing for the measurement of systolic and diastolic blood pressure as the blood begins to flow again.

In contrast, a thermometer is used to measure body temperature, while a pulse oximeter measures the oxygen saturation level of the blood. A stethoscope is utilized for listening to internal bodily sounds, such as heartbeats and breath sounds, but it does not measure blood pressure by itself. Instead, the stethoscope is often used in conjunction with the sphygmomanometer to auscultate the sounds of blood flow while measuring the pressure in the arteries. Understanding the specific functions of these instruments highlights why the sphygmomanometer is the instrument of choice for measuring blood pressure.