Introduction

There's good evidence to support home blood pressure monitoring. Three of the most useful papers that discuss the "why" and the "how" of home blood pressure monitoring are

1. O'Brien E, Asmar R, Beilin L, Imai Y, Mallion J, Mancia G, Mengden T, Myers M, Padfield P, Palatini P, Parati G, Pickering T, Redon J, Staessen J, Stergiou G, Verdecchia P. European Society of Hypertension recommendations for conventional, ambulatory and home blood pressure measurement Internet. J. Hypertens 2003 May;21(5):821-848.2009 Aug 18 Available from: http://www.ncbi.nlm.nih.gov/pubmed/12714851
2. Parati G, Stergiou GS, Asmar R, Bilo G, de Leeuw P, Imai Y, Kario K, Lurbe E, Manolis A, Mengden T, O'Brien E, Ohkubo T, Padfield P, Palatini P, Pickering T, Redon J, Revera M, Ruilope LM, Shennan A, Staessen JA, Tisler A, Waeber B, Zanchetti A, Mancia G. European Society of Hypertension guidelines for blood pressure monitoring at home: a summary report of the Second International Consensus Conference on Home Blood Pressure Monitoring Internet. J. Hypertens 2008 Aug;26(8):1505-1526.2009 Aug 18 Available from: http://www.ncbi.nlm.nih.gov/pubmed/18622223
3. Pickering TG, Miller NH, Ogedegbe G, Krakoff LR, Artinian NT, Goff D. Call to Action on Use and Reimbursement for Home Blood Pressure Monitoring. A Joint Scientific Statement From the American Heart Association, American Society of Hypertension, and Preventive Cardiovascular Nurses Association Internet. Hypertension 2008 May;:HYPERTENSIONAHA.107.189010.2008 May 27 Available from: http://hyper.ahajournals.org/cgi/content/abstract/HYPERTENSIONAHA.107.189010v1

A short-ish essay on the scientific evidence and value to our health care and society of home blood pressure monitoring is here Telehealth now: Why (in some cases) it may be healthier for patients to go online intead of to their doctor

Details

In an ideal workflow, home blood pressure monitoring will be used both to diagnose (determine if the patient really has high blood pressure) and monitor (assess a patient who has the diagnosis)

The home blood pressure measurement sequence

A single reading from a blood pressure monitor is not enough to accurately measure blood pressure, because blood pressure fluctuates throughout the day. To diagnose and treat, the goal is to keep the average blood pressure from being elevated over a long period of time.

A blood pressure measurement using a home device is an average of:

• 7 days of measurement
• Twice per day, in the early morning and in the evening (from 0600 - 0900 and 1800 - 2100)
• The first day is completely discarded, so a total of at least 12 measurements, averaged
• European society of hypertension recommends up to 25 measurements, which is 2 in the morning two in the evening
• Don't measure at work, or during the day

Here's the quote from the American Heart Association (citation above, page 5) on how frequently to monitor:

There is some agreement that correlations with ambulatory BP are more reliable if the first day’s home BP readings are discarded.52,53 Two recent analyses have recommended tak- ing between 8 and 15 readings in total,53,54 and we recom- mend following the last set of European Society of Hyper- tension guidelines to take 􏰀2 morning and 2 evening readings every day for 1 week16 but to discard the readings of the first day, which gives a total of 12 readings on which to make clinical decisions. Getting multiple readings is partic- ularly important for the initial diagnosis of hypertension, but the same procedure is also recommended to be performed at intervals in patients whose condition is thought to be stable and who require long-term follow-up. Patients should be instructed to record all the readings that they take.

Newer monitors, such as the WatchBP Home (Microlife) will not allow measurements outside this window (but this can be overridden by the patient)

There isn't good guidance on what to do for the person doing an assessment while traveling (time zones). There isn't good guidance on what to do for the person with unusual work hours. For now, good to assume that a typical patient is not traveling or working a late shift.

When blood pressure monitors are prescribed, they must be calibrated, and education provided. Fortunately, there is a billable CPT code for providing this education. Unfortunately, this billable CPT code cannot be used for home blood pressure monitors, they can only be used for a much older (and unused technology), "Ambulatory Blood Pressure Monitoring." (See This link for more information about this)

These cartoons are from Ted Eytan's Blog

Blood pressure cutoffs

• Patients with an average home blood pressure between 125/76 and 135/85 may need additional monitoring to confirm high blood pressure.
• There is less data available for diabetic patients in the home. We will need expert confirmation on this

Diagnosis

It is suggested that a person receive a diagnosis of high blood pressure by completing the sequence above, and then reporting the results to a health care professional, who combines the information obtained with the patients' other health data to make a determination.

Here is a cartoon of how this might look

And a cartoon of the workflow

However, this may be considered problematic, because one of the main reasons that patients are not adequately treated or diagnosed is "clinical inertia," or a delay in making the determination. Some providers instead may decided to not use home blood pressure measurement to make the diagnosis and only use it once a patient is diagnosed.

There are devices on the market, that when used correctly, may provide a result as accurate as a home blood pressure monitoring sequence. The technique is critical here:

Use of automated office blood pressure measurement to reduce the white coat response

Treatment

Acquiring blood pressure readings for treatment are the same as above, the only difference is sequence:

1. If a patient's blood pressure is not controlled, the sequence above is repeated every 3-4 weeks until it is
2. If a patient's blood pressure is controlled, the sequence above is repeated every 12 weeks
3. A patient needs to see their doctor once a year regardless

Here is a cartoon of what this might look like, from Ted Eytan's blog

Reporting

For a health care professional and patient to make a correct blood pressure determination, an average must be presented that satisfies the requirements above.

The requirements imply that the 7 day sequence has a start and an end, because the first day is discarded.

Outstanding questions:

1. How do we determine day 1 of a measurement cycle?
1. an a patient or physician order the start of a cycle, which sets a mark and starts guidance?
2. How do we ensure the correct number of measurements and at the right time(s)?
1. By filtering measurements that meet the criteria for use in the average?
2. By guiding patients during the cycle?
1. Proactive reminders ("It's time for your evening check")
2. Reactive reminders ("You didn't need to check this time, wait until 6:00 pm")

This might be over-thought. Let's try different approaches to get us to the outcome that we want - an accurate average with the right amount of readings, not more, not less.

Unresolved Issues/Follow-up - with suggested countermeasures

1. Mixing of patient generated blood pressure and physician generated blood pressure
• For now, let's complete the patient-generated readings-only use case from start to finish via OMHE
2. How to define a measurement cycle of 7 days?
• Let's implement the sta command, to initiate measurement, so stabp, issued by the patient will start the clock and initiate coaching
3. Behavior of the sta command - elaborate here or create a new page ?
• Suggest create a new page for general components, with child pages for BP specific components