Which instrument is used to measure arterial blood pressure?

• A. Defibrillator
• B. Suction unit
• C. Sphygmomanometer
• D. Crash cart

Answer: (C)

Measuring arterial blood pressure is done with a sphygmomanometer. This instrument uses a cuff wrapped around the upper arm, a manometer to read the pressure, and usually a bulb to inflate the cuff. When the cuff is inflated, it briefly stops blood flow in the brachial artery. As the cuff pressure is slowly released, you listen for Korotkoff sounds with a stethoscope. The pressure at which the sounds first appear is the systolic blood pressure, and the pressure at which the sounds disappear is the diastolic blood pressure. Modern automated devices still rely on the same cuff-based principle and provide a digital readout, but they function as a form of sphygmomanometer.

Defibrillators deliver an electric shock to restore a normal rhythm, suction units clear secretions from the airway, and crash carts contain emergency resuscitation equipment. None of these measure blood pressure.