Keeping a Blood Pressure Log and What to Tell the Doctor

Why a log is worth keeping

• It shows patterns, not single numbers. Blood pressure moves up and down, so one reading says little.
• It helps the doctor decide whether to start, continue or review treatment.
• It reveals time-of-day effects, such as high morning readings or low readings after tablets.
• It helps spot medicine side effects, such as low readings with dizziness.
• It reduces repeat tests and misunderstandings.
• It gives the person a sense of control and a shared task with the family.

See white-coat and masked hypertension for how home logs can differ from clinic readings.

What to write down

For each reading, record:

• Date and time.
• Systolic and diastolic numbers (the upper and lower).
• Pulse rate.
• Which arm or wrist was used.
• Position: sitting, usually. Mention if lying or standing.
• Notes: anything that might affect the number, such as poor sleep, pain, tea taken, medicines taken or missed, a stressful event, illness, a heavy meal, or feeling dizzy.

A simple table with columns for date, time, upper, lower, pulse and notes is enough. Large, clear writing helps older eyes. Leave room for two readings at each sitting. Print a month's worth of sheets or rule lines in a notebook.

Setting up the log

1. Choose a format. A notebook, a printed chart or a phone note all work. Many families use a ruled notebook because it never runs out of battery. 2. Keep it with the monitor in the same box, with a pen attached by a string, so the log is never separated from the device. 3. Decide who writes. If your parent can write, let them. If not, a helper should write while the person calls out the numbers; see talking blood pressure monitors for low vision. 4. Put the doctor's instructions on the first page: how often to measure, which arm, the target numbers set by the doctor and when to call. 5. Date the pages and keep old ones in a folder; a year of readings is valuable.

What schedule to log

Follow the doctor's advice. A common pattern before a review is two readings in the morning and two in the evening, a minute apart, for about seven days. At other times, a few readings per week may be enough for a stable person. Taking readings many times a day is rarely helpful and may cause worry. If the doctor changes a medicine, they may ask for a fresh run of readings. For the technique, see how to measure blood pressure at home accurately.

Doing the average

Doctors often want the average of home readings. A typical method:

1. Take all readings from the days requested, usually seven days. 2. Some doctors ignore the first day's readings, because people are often more anxious or still learning the method. 3. Add all the upper numbers and divide by the number of readings, then do the same for the lower numbers. 4. Write the average at the bottom of the page, along with the highest and lowest readings.

A phone calculator can help, and many monitors give an average of recent readings. If you are unsure, bring the log to the doctor and let them do it.

What to tell the doctor

At the appointment, or in a call, be ready to say:

• The average home reading and the range, with dates.
• How readings differ between morning and evening, or after medicines.
• Any readings far from usual, high or low, and what was happening.
• Symptoms: headaches, dizziness, blurred vision, chest discomfort, breathlessness, swelling, falls or fainting.
• Medicines: the names, doses and times, including anything bought over the counter such as painkillers, cold remedies and herbal products. Never change them yourself.
• Missed doses or side effects.
• Lifestyle changes: salt intake, weight change, sleep, alcohol, smoking, exercise.
• The monitor: brand, model, cuff size and whether you compared it with the clinic's device.

Having this written on one page, perhaps with your health record, speeds the consultation. For video or phone consultations, send a photo of the log before the call; see using home readings in a teleconsultation.

Questions to ask

• What is the target range for my parent, at home and in the clinic?
• How often should we measure and for how long?
• What should we do if a reading is above or below a certain level?
• Which symptoms should make us call urgently?
• Should we check standing readings as well?
• When should we bring the monitor to the clinic for a check?

Reading the log yourself, with care

You can use the log for general orientation, as long as you remember that doctors set individual targets. Broadly, many guidelines treat home averages below about 130/80 as the aim for many adults and averages of 135/85 or above as high, but older adults and people with other conditions may have different goals. See normal ranges for older adults. Watch for:

• A gradual rise over weeks.
• Very low readings, particularly with dizziness.
• Large swings between readings.
• Differences between arms.

These are reasons to tell the doctor, not to change medicines.

Making it work in a busy family

• Link the reading to a daily habit, such as the morning tea (after the reading, not before) or the evening news.
• Put the monitor somewhere visible but safe.
• Make one person responsible for the log, but share the job on holidays.
• If your parent lives alone, a relative can call during the reading and note the numbers, or the parent can send a photo of the display.
• Keep a spare copy of the log, for example a photo on a phone, in case the notebook is lost.
• Do not turn the log into a test that your parent feels they can fail. Thank them for the effort.

Common problems

• Gaps in the log. A few missed days are fine. Tell the doctor about them.
• Only recording high readings. This gives a false impression. Record all.
• Writing the best reading. Record every reading.
• Illegible handwriting. Use large print or have a helper write.
• No notes. A short note beside an odd number often explains it.
• Lost monitor memory after battery change. Copy readings to the log first.

When to ask a professional

Take the log and the monitor to the doctor, nurse or pharmacist, and ask them to check your parent's technique and to confirm the monitor is accurate. Ask for advice if averages stay above or below the target, if readings swing widely, or if your parent has symptoms such as dizziness, fainting, headaches or swelling. Do not stop, add or adjust any medicine without the doctor. Call 112 immediately if a high reading comes with chest pain, severe headache, weakness on one side, difficulty speaking, confusion or severe breathlessness.