Home blood pressure monitoring - First in a series

Background

Office blood pressure measurement is the traditional tool for screening, diagnosis and management of patients with suspected disorders of blood pressure regulation - namely hypertension, hypotension or a combination of the two. Office blood pressure is limited though, in that only a small number of measurements can be taken in an environment in which the patient doesn't feel completely at ease. This fact may contribute to suspected white coat hypertension, suspected white coat effect in a known hypertensive, masked hypertension or resistant hypertension. Home blood pressure monitoring (HBPM) on the other hand, allows a patient to take as many measurements needed over a number of days in their own comfortable and relaxed environment - home.

1 - Presentation

Studies have shown that HBPM relative to office blood pressure leads to an improvement in blood pressure control rates (1) and is a better prognostic indicator (2-6). It provides physicians and patients alike with a more detailed assessment of response to the lifestyle modifications and changes in drug treatment. Patients can actively participate in their own management by being given first hand opportunity to observe the impact of lifestyle changes and drug treatment.
Home blood pressure monitoring is used to gain more information to make diagnosis of hypertension, white coat hypertension or masked hypertension, adjust treatment upwards to improve overall control or reduce treatment if patient develops hypotensive symptoms.
Nevertheless, self-measurement at home can lead to panic or anxiety. It may also lead to self-modification of the treatment regimen. Home blood pressure monitoring should be discouraged in such cases. Out of office blood pressure monitoring refers to both 24-hour ambulatory blood pressure monitoring and home blood pressure monitoring. Unless a patient is equipped with the latest home devices that can take night recordings, home blood pressure monitoring does not provide information about the night time blood pressure levels, presence or absence of nocturnal dip and morning surge, as compared to ambulatory blood pressure monitoring, which does.

2 - Method

Here presented are the conditions that can help ensure that data entry and averaging be well conducted. 
To ensure that blood pressure measurements are valid, individuals undergoing home blood pressure monitoring need to be fully instructed, educated and trained with the following information regarding how to conduct their home readings. Here are the education and training instructions for a subject undertaking of home BP:

1. Ask questions - Before starting a period of monitoring, ask your nurse to explain the procedure to you and have some readings taken under supervision. Do not be afraid to ask questions if you are not sure
2. No caffeine - Do not drink tea, coffee or other caffeine containing drinks such as cola less than half an hour before  Blood pressure measurement
3. No smoking - Do not smoke less than half an hour before blood pressure measurement
4. Have rested 5 min - If you exercise (e.g.  going for a walk) prior to blood pressure measurement please make sure you rest for at least 5 minutes before taking the reading
5. Avoid talking - Talking during a reading will raise your blood pressure. Stay still and quiet during the measurement
6. Have gone to the toilet - Empty your bladder before you measure your blood pressure as a full bladder will cause a rise in blood pressure
7. Relax - Try to be as relaxed as possible.  If you feel anxious, try to take a few deep breaths before blood pressure measurement
8. Use same arm, rested on a firm surface - Use the same arm for blood pressure measurement, using right sized cuff and blood pressure monitor recommended by your nurse or the doctor. During the measurement arm should be rested on a firm surface such as a table with feet on floor with legs uncrossed
9. Do 2x3 readings x 5-7 days: Take three readings twice daily (ideally before breakfast and the evening meal for consistency) each about 1-2 minutes apart for 5-7days as advised by your nurse or the doctor. If your monitor does not have a memory function, please write down readings on the Home BP Monitoring sheet provided (see Table 3)

Data entry: Registration of the data, if done by hand, should be made using a monitoring sheet that will provide the documentation on (Table 2) to attest that the recording have been entered twice in the morning and the same number of times in the evening at an interval of 1-2 minutes for 4-7 days.

3 - Device and phone applications 

It is recommended to use a fully automated oscillometric upper arm device. The British hypertension society and Irish patient education websites provide a list of the validated devices - they start at 50 euros. Information via telemetry to a designated hypertension unit is possible in some models.
Wrist devices should be used in patients who cannot apply cuff easily such as in obesity, in case of conical arm shape or in elderly patients with a compromised dexterity. With wrist monitors, the arm should be kept at the heart level - some of the wrist monitors come equipped with a heart position sensor to make this position easy to set and sustain. Most manufacturers will service and calibrate their own machines but this is costly and certainly when it comes to the less expensive devices it may be cheaper to buy a newer one instead. The details of service centres can be found in the instruction manual that comes with the devices. 

Conclusions

Hypertension is an important and treatable cardiovascular risk factor and home blood pressure monitoring provides detailed information in a more comfortable environment for the patient. The procedure is easy to learn and follow and with blood pressure monitors becoming more affordable, home blood pressure monitoring has established itself as an important tool in the management of hypertension.