In-clinic BP measurements are one of the cornerstones of general practice and a key contributor to the assessment of absolute cardiovascular risk.1,2 These values are also important for monitoring a patient's response to BP-lowering therapy.
However in-clinic readings are just a snapshot of an individual's blood pressure and may not accurately reflect a patients underlying BP due to a number of reasons, including:2,3
- inherent variability coupled with small number of BP readings
- poor technique due to common errors (eg, cuff over clothing, incorrect cuff size, device not calibrated)
- patterns of BP such as white coat hypertension, masked hypertension, nocturnal non-dipping.
Establishing a best practice routine for the in-clinic assessment of BP can help minimise confounders such as those described above and increase measurement accuracy.In-clinic readings are just a snapshot and may not accurately reflect a person's underlying BP.2,3
General principles for in-clinic BP measurements
In-clinic BP can be taken using a variety of methods:
- recording taken by the doctor
- recording taken by a health professional other than a doctor – this has been shown to reduce the white coat effect4
- automatic, non-observed recording by an automated oscillometric device in a seated patient who has been resting alone in a quiet room — this is considered ideal, and may also reduce the white-coat effect.1,2
All BP measuring devices should be serviced at least once per year.5
Multiple factors can affect the accuracy of an in-clinic BP measure and the magnitude of the mmHg discrepancy.6
Factors that can impact the accuracy of in-clinic BP readings.6
(increase in mmHg SBP)
(increase in mmHg SBP)
|Cuff over clothing (5–50)||Talking or active listening (10)|
|Cuff too small (10)||Distended bladder (15)|
|Patient back unsupported (6–10)||Smoking or caffeine within 2 hours of measurement (6–20)|
|Patient arm unsupported|
– sitting (1–7)
– standing (6–8)
To measure in-clinic BP accurately, current guidelines recommend:5,7
- The patient be seated and relaxed – allow them a few minutes to sit quietly and calmly before measuring.
- Multiple measurements taken at different times – at least two measurements on each occasion, and repeated one week or more apart.
- Measuring BP on both arms at the first assessment – if there is a discrepancy of more than 5 mmHg, use the arm with the highest reading for all future readings
- Recording the result for systolic and diastolic BP – repeating the procedure after 30 seconds.
Average the readings. If the first two readings differ by more than 10 mmHg systolic or 6 mmHg diastolic, or if initial readings are high, have the patient rest quietly for 5 minutes then take several readings until consecutive readings do not vary by greater than these amounts.
For automated devices, three measurements should be obtained with the average of the second and third readings recorded.7