Which Korotkoff phase corresponds to the systolic blood pressure reading?

• A. Phase I is the first appearance of tapping sounds, indicating systolic BP.
• B. Phase II is the systolic reading.
• C. Phase IV is the systolic reading.
• D. Phase V is the systolic reading.

Answer: (B)

Systolic pressure is determined by the moment the artery first starts to reopen and blood flow creates audible tapping as you deflate the cuff. That initial tapping sound marks the systolic reading, because it reflects the pressure at which systolic blood flow resumes.

As you continue to release the cuff, the sounds change: they may become muffled, then more distinct again, and finally disappear. The last audible sound (or the point of complete silence) corresponds to the diastolic pressure. In most adults, diastolic is read at the point where the sounds disappear.