How do I manually check blood pressure (BP)?

How to Manually Check Blood Pressure

To manually check blood pressure, have the patient sit quietly for 5 minutes with back and arm supported, use a validated device with appropriate cuff size positioned at heart level, take three measurements 1-2 minutes apart, and average the last two readings. 1

Patient Preparation (Critical First Step)

Before taking any measurements, proper patient preparation is essential to ensure accuracy 1:

• Have the patient sit in a chair with feet flat on the floor and back supported for at least 5 minutes 1
• Ensure the patient has avoided caffeine, exercise, and smoking for at least 30 minutes before measurement 1
• Confirm the patient has emptied their bladder 1
• Neither the patient nor the observer should talk during the rest period or during measurement 1
• Remove all clothing covering the cuff placement location 1

Common pitfall: Measurements taken while the patient is sitting or lying on an examining table without proper back support do not fulfill these criteria and will yield inaccurate results 1.

Equipment Setup and Positioning

Device Selection

• Use a validated blood pressure measurement device that has been calibrated periodically 1
• For manual auscultatory measurement, use either an aneroid or calibrated device (mercury sphygmomanometers are banned in most countries) 1
• Either the stethoscope diaphragm or bell may be used for auscultatory readings 1

Cuff Size and Placement

• Select the correct cuff size such that the bladder encircles 75-100% (or 80%) of the patient's arm circumference 1
• Incorrect cuff size is a major source of error: smaller cuffs overestimate and larger cuffs underestimate blood pressure 1
• Support the patient's arm (e.g., resting on a desk) with the middle of the cuff positioned on the upper arm at the level of the right atrium (midpoint of the sternum) 1

Critical positioning detail: The arm must be at heart level—measurements taken with the arm below heart level will be falsely elevated due to hydrostatic pressure 2, 3.

Measurement Technique

Initial Assessment

• At the first visit, measure blood pressure in both arms 1
• Use the arm with the higher reading for all subsequent measurements 1
• If systolic BP differs by >10 mmHg between arms, obtain further measurements to ensure the difference is consistent 1
• If the difference is >20 mmHg, consider further investigation for arterial stenosis or coarctation of the aorta 1

Manual Auscultatory Method

For accurate manual measurement using the auscultatory technique 1:

1. Palpate the radial pulse and inflate the cuff until the pulse disappears to estimate systolic BP 1
2. Inflate the cuff 20-30 mmHg above this estimated systolic level 1
3. Deflate the cuff at a rate of 2 mmHg per second while listening for Korotkoff sounds 1
4. Record systolic BP at the onset of the first Korotkoff sound 1
5. Record diastolic BP at the disappearance of all Korotkoff sounds (5th Korotkoff sound) 1
6. Document readings to the nearest even number 1

Number of Measurements

• Take three measurements with 1-2 minutes between each reading 1
• Average the last two readings for the final blood pressure value 1
• If the first reading is <130/85 mmHg, no further measurements are required 1

Important note: Separate repeated measurements by 1-2 minutes to allow for recovery and avoid falsely low readings 1.

Additional Assessments

Orthostatic Hypotension Screening

• Assess for orthostatic hypotension at the initial visit and whenever symptoms suggest postural hypotension 1
• After 5 minutes of rest in sitting or lying position, measure BP at 1 minute and/or 3 minutes after standing 1
• A drop of ≥20/10 mmHg (systolic/diastolic) defines orthostatic hypotension 1

Heart Rate and Rhythm

• Record heart rate at the initial visit and exclude arrhythmia by pulse palpation 1

Documentation and Interpretation

• Record both systolic and diastolic BP values 1
• Note the time of most recent BP medication taken before measurements 1
• Use an average of ≥2 readings obtained on ≥2 occasions to estimate the individual's level of BP 1
• Provide patients the systolic/diastolic readings both verbally and in writing 1
• Blood pressure of 2-3 office visits ≥140/90 mmHg indicates hypertension 1

Key Pitfalls to Avoid

Position-related errors: Body position significantly influences BP readings—supine measurements are 8-10 mmHg higher for systolic BP compared to seated measurements when the arm is properly positioned at heart level in both positions 2. Even small deviations in arm position (such as resting the arm on the examination bed rather than at heart level) can cause falsely elevated readings of 4-5 mmHg systolic and 3-4 mmHg diastolic 2.

Equipment maintenance: Ensure regular maintenance and recalibration of BP measuring equipment according to manufacturer's instructions to ensure accuracy 4. Devices older than 4 years may be inaccurate and should be replaced if found to be inaccurate 1.

Talking during measurement: Any conversation during the rest period or measurement will elevate readings and should be strictly avoided 1.