In helping a customer select a home blood pressure machine, in addition to preferring a validated kit, customers should also ensure the cuff size is appropriate to wrap around the upper arm at the mid-point between the shoulder and the elbow. Home blood pressure kits can often be supplied with a ‘medium’ sized cuff, so a large or small cuff may need to be ordered separately.¹⁴ An undersized cuff is likely to overestimate blood pressure, while too big a cuff may underestimate.¹⁵

Ease of use, comfort, time taken for readings, and price, may also be factors, but a Consumers’ Association Which? report in 2015 found four best buys for under £25, outperforming machines costing £100.19

Other factors to consider include:¹⁹

• Whether results can be stored, and what level of detail – such as time and date – is recorded
• Whether results are sent to a smartphone or tablet by Bluetooth or wifi/ apps, or whether data is transferred by memory stick or cable to a PC
• The power source – whether it is battery operated or has a mains adaptor
• Additional functions, eg, blood pressure averaging, risk monitoring and irregular heartbeat detectors.

Factors such as muscle tremors, abnormal heart rhythms, weak pulse or very low blood pressure due to shock may mean a reading is not possible. Users should also be discouraged from talking or moving while the blood pressure is being taken.¹⁵