21/11/2025
How Blood Pressure Measurement Works
1️⃣ Put the cuff on the arm
• The cuff compresses the brachial artery (main artery in the upper arm).
2️⃣ Pump the bulb → cuff tightens
• Pressure becomes higher than systolic →
Artery is fully closed → no blood flows
→ You hear nothing with the stethoscope.
3️⃣ Slowly release valve
• Cuff pressure drops gradually.
4️⃣ FIRST sound = SYSTOLIC BP
• When artery starts to open, blood squirts through.
• This creates Korotkoff sounds (“tap-tap”).
• ➡️ First tapping sound = Systolic BP
5️⃣ Continue releasing
• Artery opens more and more.
6️⃣ Sound disappears = DIASTOLIC BP
• When the artery is fully open, flow becomes smooth.
• No turbulence → sound disappears.
• ➡️ Last sound = Diastolic BP
