Good technique with validated, automated blood pressure machine use is key to accuracy, according to an updated scientific statement on BP measurement from the American Heart Association (AHA).

To ensure accurate measurement of BP, the AHA has issued recommendations on training in auscultatory BP measurement, assessment of knowledge of the doctor, skills of the technician or provider, among others.

Among the key recommendations are:

• The observer must be able to see the manometer dial at eye level without straining and read the sphygmomanometer no further than 3 ft away.
• The observer must be able to hear the Korotkoff sounds and be able to conduct the cuff deflation, listen to Korotkoff sounds and read the sphygmomanometer simultaneously.
• Only well maintained validated devices must be used.
• Observers should also know how to interpret and how and when to communicate BP readings to healthcare providers and patients.
• Retraining of healthcare professionals should be considered every 6 months to 1 year.
• The appropriate cuff size should be selected.

o    Arm circumference should be measured at the midpoint of the acromion and olecranon.

o    BP cuff bladder length should be 75-100% of the measured arm circumference.

o    BP cuff bladder width should be at 37-50% of the patient’s arm circumference.

o    Avoid rolling up the shirtsleeves as a tourniquet effect may result.

• The observer must understand variability of  BP by time of day, exercise, and timing of antihypertensive medication consumption

o    Systolic BP is 3–10 mmHg higher in the supine than the seated position.

o    Diastolic BP is ≈1–5 mmHg higher when measured supine vs seated

o    Crossing legs during BP measurement may raise SBP by 5–8 mmHg and DBP by 3–5 mmHg.

o    If a patient’s back is not supported (e.g., the patient is seated on an examination table), SBP and DBP may be increased by 5-15 and 6 mmHg, respectively

AHA has also described following six steps for proper seated office BP measurement: 

1. Properly prepare the patient
2. Use proper technique for BP measurements
3. Take the proper measurements needed for diagnosis and treatment of elevated BP/hypertension
4. Properly document accurate BP readings
5. Average the readings
6. Provide BP readings to patient

(Source: Hypertension. 2019 Mar 4. Epub ahead of print)