What is the correct method for taking blood pressure (BP)?

The Correct Method for Blood Pressure Measurement

Blood pressure should be measured with the patient seated quietly for 3-5 minutes, using a validated device with appropriate cuff size, arm supported at heart level, and averaging at least 2 readings taken 1-2 minutes apart. 1

Patient Preparation

• Ensure patient is relaxed in a quiet room with comfortable temperature
• Patient should avoid smoking, caffeine, and exercise for at least 30 minutes before measurement
• Patient should empty bladder before measurement
• Patient should be seated with:
  • Back supported on chair
  • Feet flat on floor (uncrossed)
  • No talking before, during, or between measurements
  • Rested for 3-5 minutes before first reading 1

Proper Positioning

• Patient should be seated (preferred position for routine measurements)
• Arm should be supported (e.g., resting on table)
• Mid-arm positioned at heart level (midpoint of sternum)
• Remove all clothing covering the location of cuff placement 1

Equipment and Technique

1. Device selection:

   • Use a validated electronic (oscillometric) upper-arm cuff device
   • Alternatively, use a calibrated auscultatory device with proper technique 1

2. Cuff size:

   • Use appropriate cuff size where bladder encircles 80% of the arm
   • Incorrect cuff size leads to inaccurate readings (smaller cuff overestimates BP, larger cuff underestimates BP) 1, 2

3. Measurement protocol:

   • At first visit, record BP in both arms and use the arm with higher reading for subsequent measurements
   • For auscultatory method:
     • Palpate radial pulse and inflate cuff 20-30 mm Hg above point of pulse obliteration
     • Deflate cuff at rate of 2 mm Hg per second
     • Record systolic BP at onset of first Korotkoff sound (phase I)
     • Record diastolic BP at disappearance of all Korotkoff sounds (phase V)
     • Use nearest even number when recording values 1

Proper Documentation and Averaging

• Take at least 2-3 readings with 1-2 minutes between them
• Calculate the average of the readings (typically the last 2)
• If BP of first reading is <130/85 mm Hg, no further measurement may be required in some protocols 1
• Provide patients with their BP readings both verbally and in writing 1

Common Errors to Avoid

1. Inadequate rest period before measurement
2. Improper patient positioning (sitting or lying on examination table)
3. Unsupported arm or arm not at heart level (can alter readings by 3-10 mm Hg) 3
4. Inappropriate cuff size
5. Talking during measurement
6. Rapid cuff deflation for auscultatory readings
7. Relying on a single reading 1, 4

Special Considerations

• For diagnosis of hypertension, out-of-office BP measurements (home or ambulatory monitoring) are recommended to confirm the diagnosis and rule out white coat hypertension 1, 5
• Standing BP should be measured in treated hypertensives after 1 minute and again after 3 minutes when there are symptoms suggesting postural hypotension, and at the first visit in elderly patients and those with diabetes 1

By following these standardized procedures, you can ensure accurate BP measurement, which is essential for proper diagnosis and management of hypertension.