What is the proper technique for manually measuring blood pressure using a sphygmomanometer in a patient with potential hypertension and/or cardiac conditions?

Proper Technique for Manual Blood Pressure Measurement with Sphygmomanometer

To accurately measure blood pressure manually, have the patient sit quietly for more than 5 minutes with feet flat on the floor and back supported, position the cuff at heart level on a supported arm, inflate 20-30 mmHg above the estimated systolic pressure (determined by palpating radial pulse obliteration), then deflate at 2 mmHg per second while listening for Korotkoff sounds to identify systolic (first sound) and diastolic (disappearance of sounds) pressures. 1

Step 1: Patient Preparation (Critical for Accuracy)

Before measurement, ensure the following conditions are met:

• Patient must sit quietly for >5 minutes in a chair with feet flat on the floor and back fully supported 1
• Avoid caffeine, exercise, and smoking for at least 30 minutes before measurement 1
• Ensure bladder is empty before starting 1
• Neither patient nor observer should talk during rest period or measurement 1
• Remove all clothing covering the cuff placement site 1

Common pitfall: Measurements taken with patients sitting on an examination table (legs dangling, back unsupported) do NOT fulfill proper criteria and will yield inaccurate readings 1

Step 2: Equipment Setup and Positioning

Use validated and calibrated equipment:

• Use only validated sphygmomanometers that are calibrated periodically 1
• Select correct cuff size such that the bladder encircles 80% of the arm circumference 1
• Document if using larger or smaller than normal cuff 1

Proper arm positioning is critical:

• Support the patient's arm (e.g., resting on a desk) 1
• Position the middle of the cuff at the level of the right atrium (midpoint of sternum) 1
• Arm position errors can significantly alter readings - measurements with arm unsupported or below heart level can overestimate blood pressure by 4-10 mmHg 2, 3

Stethoscope placement:

• Either diaphragm or bell may be used for auscultatory readings 1

Step 3: Measurement Technique

Follow this precise sequence:

1. At first visit, measure BP in both arms and use the arm with the higher reading for all subsequent measurements 1

2. Estimate systolic pressure by palpation first:

   • Palpate the radial pulse while inflating the cuff 1
   • Note the pressure at which the pulse disappears (radial pulse obliteration pressure) 1
   • This step is essential to avoid missing an auscultatory gap, particularly in elderly patients 4

3. Inflate the cuff 20-30 mmHg above the estimated systolic pressure 1

4. Deflate the cuff at exactly 2 mmHg per second while listening for Korotkoff sounds 1

   • Too rapid deflation is a common technical error that leads to inaccurate readings 5

5. Separate repeated measurements by 1-2 minutes 1

Step 4: Recording Blood Pressure Values

Document readings precisely:

• Systolic BP = onset of first Korotkoff sound 1
• Diastolic BP = complete disappearance of all Korotkoff sounds 1
• Record to the nearest even number 1
• Note the time of most recent BP medication taken before measurement 1

Step 5: Averaging and Reporting

Multiple measurements are required:

• Use an average of ≥2 readings obtained on ≥2 separate occasions to estimate the individual's true blood pressure level 1
• Provide patients with SBP/DBP readings both verbally and in writing 1

Special Considerations for Elderly Patients

Be aware of auscultatory gap phenomenon:

• An auscultatory gap (temporary disappearance of Korotkoff sounds between systolic and diastolic pressure) occurs more frequently in elderly patients and can lead to significant underestimation of systolic pressure 4
• To eliminate auscultatory gap: Elevate the arm overhead for 30 seconds before inflating the cuff, then return to proper position 4
• Always use palpatory method first to estimate systolic pressure as described above 4

Common Pitfalls to Avoid

Technical errors that compromise accuracy:

• Incorrect arm position (unsupported or not at heart level) can alter readings by 5-10 mmHg 2, 3
• Wrong cuff size leads to systematic over- or underestimation 1
• Talking during measurement elevates readings 1
• Inadequate rest period before measurement 1
• Too rapid cuff deflation causes missed readings 5
• Measuring over clothing introduces error 1