What does zeroing the sphygmomanometer accomplish?

• A. Atmospheric pressure
• B. The patient’s baseline blood pressure
• C. The device’s last reading
• D. Calibration setting

Answer: (A)

Zeroing the sphygmomanometer sets the gauge’s reference to atmospheric pressure. By establishing a zero point at the ambient air pressure, the readings you observe are true pressures above that baseline, not distorted by the surrounding environment. This ensures that when you inflate the cuff, the numbers reflect the cuff pressure accurately, leading to correct systolic and diastolic values. It doesn’t directly set the patient’s baseline blood pressure, nor does it relate to the device’s last reading; it’s about canceling out ambient pressure so measurements start from a true zero.