PP on a blood pressure monitor: what the third number means

Two numbers on the display are familiar to everyone. On some monitors a third abbreviation appears beside them: PP, often with a value between 30 and 70.

The question that follows is a fair one: have I just measured a third blood pressure value that nobody explained to me? No. PP is not a measurement at all. It is a calculation the device has carried out for you.

What PP stands for

PP is short for pulse pressure. The German Hypertension League lists the same value in its glossary as Blutdruckamplitude and defines it as the „gap between the upper (systolic) and lower (diastolic) blood pressure“.

The arithmetic behind it is a subtraction:

PP = upper value − lower value
120 over 80 gives PP 40 · 135 over 85 gives PP 50 · 160 over 80 gives PP 80

You can work this out yourself at any time. A monitor that displays PP takes nothing off your hands that you could not do in your head – it only saves you the intermediate step.

Why PP is not a measured value – and why that matters

This sounds like hair-splitting, but it is the practically most important point on this page.

Your monitor measures two quantities. Both carry a measurement uncertainty. An upper-arm device validated to DIN EN ISO 81060-2 may deviate from the reference by up to 5 mmHg on average. When you subtract two such values from one another, their deviations add up in the difference – they do not cancel out.

The same applies to user error. A cuff that is too loose, an arm below heart level, talking during the measurement: each of these shifts the upper and the lower value by different amounts – and therefore often changes the difference more than it changes either single value. Which errors those are in detail is covered in Measuring blood pressure correctly.

On top of that comes natural variation: blood pressure changes continuously with the breathing rhythm, so two readings in a row are never identical. That variation lands in the PP in full.

The practical consequence: a single PP value on the display says very little. The number only becomes meaningful as the average of a whole week of readings – systolic and diastolic averaged separately, then subtracted.

The other abbreviations on the display

PP rarely appears alone. Which abbreviations a device shows is set by the manufacturer – your device's instructions for use are always the authority. Common ones are:

• SYS – the upper, systolic value in mmHg
• DIA – the lower, diastolic value in mmHg
• PUL or Pulse – the heart rate in beats per minute. Not to be confused with PP
• PP – the gap between the two pressure values, calculated
• MAP – the mean arterial pressure, also calculated, but by a different formula than PP
• A heart symbol with a wavy line – an indication of an irregular heartbeat during the measurement

The two most common mix-ups deserve a plain statement: PP is not the pulse – the pulse counts beats per minute, PP is a pressure in mmHg. And PP is not MAP – both are calculated, but they describe different things.

What the number says – and from what point

A clarification is needed here that many guides leave out: there is no officially defined normal range for pulse pressure. For blood pressure itself, 140/90 mmHg in the practice and 135/85 mmHg at home are clearly defined – for the gap, no corresponding table of limits exists.

What does exist is a threshold. The German Hypertension League writes in its patient guide:

„According to studies, cardiovascular risk increases when the pulse pressure value is permanently greater than 65 mmHg.“

For orientation: the usual values of healthy adults work out to an order of magnitude around 40 to 50 mmHg. That is a calculation, not a limit.

And it is a statement about populations, not about you. A single PP of 67 on the display means nothing on its own – neither a diagnosis nor a need to act. Why the gap says anything at all about the elasticity of the large vessels is covered in detail in Pulse pressure: what the gap between your readings reveals.

Is a monitor worth buying because it shows PP?

The honest answer is: not as a reason to buy. A PP display adds no measuring capability to the device. It performs a subtraction that you can do yourself with two numbers and ten seconds – and the result is exactly the same.

What really distinguishes one monitor from another are the things that happen before the arithmetic: whether it is clinically validated to DIN EN ISO 81060-2, whether the cuff fits your upper-arm circumference, whether it measures at the upper arm rather than the wrist. Those points decide the quality of both input values – and therefore the quality of the PP as well.

The display is convenient nonetheless, particularly if you want to track the value over weeks. It simply does not replace checking the device itself.

What to usefully do with the value

1. Do not judge it in isolation. Record the two main values as usual over seven days, twice each morning and evening.
2. Leave out the first day (habituation effect) and average systolic and diastolic separately from the rest.
3. Only then subtract. That number is dependable – the one on the display is not.
4. Watch the change, not an absolute value. A gap that has shifted noticeably against earlier series of readings is the more interesting signal.

All of this presupposes an upper-arm device validated to DIN EN ISO 81060-2 with a cuff of the right size – how to recognise that is covered in Which blood pressure monitor is the most accurate? How to read the two main values themselves is shown in the blood pressure values table.

When to seek medical advice

• If the averaged gap from a week of readings is permanently above 65 mmHg
• If the gap is strikingly small and symptoms accompany it
• If the gap has changed markedly against earlier series of readings
• With shortness of breath on exertion, dizziness, tightness in the chest, a drop in performance or swollen ankles
• If your device repeatedly indicates an irregular heartbeat

Never change existing blood pressure medication on your own on the basis of a display value. In case of sudden severe chest pain, shortness of breath, cold sweat, speech or vision disturbances or one-sided paralysis: call the emergency services on 112 immediately.