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3.3A Tips on Taking Accurate Measurements
In morning before breakfast, 2
hours after dinner, before taking
medication.
Avoid coffee and smoking within the
hour, and no exercise 30 minutes
before measuring.
Do not speak while taking the
measurement.
Sit with legs uncrossed so as not to
restrict blood flow.
Empty bladder (if necessary).
Rest quietly for 5 minutes.
Remain calm and quiet while the
measurement is in process.
Take measurements on the non
dominant arm.
Sit with back supported and
measurement arm resting on a table.
Sit with feet flat on the floor.
Ensure that the BP monitor is level
with the heart while the arm is
supported on the table.
3.3B Common Sources of Error
All efforts by the patient to support the arm can increase the blood pressure. Make sure the patient
is in a comfortable, relaxed position and is not activating any of the muscles in the measurement
arm during the measurement. Use a cushion for support if necessary.
ATTENTION!
Comparable blood pressure measurements always require the same conditions with a peaceful
and calm environment. Ensure that you take measurements under the same conditions to obtain an
accurate estimate of blood pressure variation patterns.
• If the arm artery lies considerably lower or higher than the heart, an erroneous value of blood
pressure is measured. Each 15 cm difference in height results in a measurement error of 10
mmHg.
• A loose cuff causes false measurement values.
• With repeated measurements, blood accumulates in the arm, which can lead to false results.
Consecutive blood pressure measurements should be repeated after at least a 15 second
pause or after the arm has been held up in order to allow the accumulated blood to flow away.
