What is the proper method for measuring blood pressure (B/P) by obliteration?

Proper Method for Measuring Blood Pressure by Obliteration

For accurate blood pressure measurement by obliteration, first palpate the radial pulse and inflate the cuff 20-30 mmHg above the point where the pulse disappears (pulse obliteration pressure), then deflate at 2 mmHg per second while auscultating for Korotkoff sounds to determine systolic and diastolic readings. 1

Patient Preparation

Before measuring blood pressure, proper patient preparation is essential:

• Have patient relax in a chair (not exam table) with feet flat on floor and back supported for >5 minutes
• Ensure patient has avoided caffeine, exercise, and smoking for at least 30 minutes
• Confirm patient has emptied their bladder
• Maintain silence during rest period and measurement (no talking by patient or provider)
• Remove all clothing covering the location of cuff placement 1, 2

Equipment and Positioning

• Use a validated and calibrated blood pressure device
• Support the patient's arm at heart level (midpoint of sternum)
• Select appropriate cuff size (bladder should encircle 80% of the arm)
• Position middle of the cuff on the patient's upper arm 1

The Obliteration Method Technique

1. First Visit: Record BP in both arms; use the arm with higher reading for subsequent measurements 1

2. Pulse Obliteration:

   • Palpate the radial pulse
   • Inflate the cuff until the pulse disappears (pulse obliteration pressure)
   • Note this value as an estimate of systolic BP 1

3. Auscultatory Measurement:

   • Inflate the cuff 20-30 mmHg above the pulse obliteration pressure
   • Place stethoscope over brachial artery (either diaphragm or bell can be used)
   • Deflate cuff at a rate of 2 mmHg per second
   • Listen for Korotkoff sounds 1

4. Recording:

   • Record systolic BP as the onset of the first Korotkoff sound (phase 1)
   • Record diastolic BP as the disappearance of all Korotkoff sounds (phase 5)
   • Use the nearest even number when recording values 1

Follow-up and Documentation

• Separate repeated measurements by 1-2 minutes
• Average ≥2 readings obtained on ≥2 occasions to estimate BP level
• Provide BP readings to patient both verbally and in writing
• Document time of most recent BP medication taken before measurement 1

Common Pitfalls and How to Avoid Them

• Improper cuff size: Using too small a cuff can falsely elevate readings; ensure proper sizing (80% of arm circumference) 1
• Rapid deflation: Deflating faster than 2 mmHg per second can lead to underestimation of systolic and overestimation of diastolic pressure 1
• Digit preference: Avoid rounding to nearest 0 or 5; record to nearest even number 1
• White coat effect: Consider out-of-office measurements if suspected 1
• Arm position: Unsupported arm or arm not at heart level can cause inaccurate readings 1, 2
• Talking during measurement: Can significantly increase readings 2

Special Considerations

• Atrial fibrillation: Oscillometric monitors may not be accurate; multiple auscultatory measurements are recommended 1
• Orthostatic hypotension: Consider assessment (≥20/10 mmHg drop at 1 and/or 3 min after standing) at initial diagnosis 1
• Retraining: Healthcare professionals should undergo regular retraining in BP measurement technique every 6 months 1

The pulse obliteration method is particularly valuable as it prevents underestimation of systolic BP due to the auscultatory gap that can occur in some patients, especially those with hypertension 1, 3.