Auscultated BPs

[AnthonyM83]

That's not a terribly good analogy, as most watches have marks for minutes as well. I'm sure in the booklet that comes with a watch, it would tell you that the minutes hand will take 60 minutes to go all the way around, and 5 minutes to move between the hour marks. We just dont have to read that because we know.

As a counter-analogy, taking an even blood pressure with a manual cuff is like saying it's 12:19 and 30 seconds because the minute hand is between the 19 and the 20. It's just not accurate.

Actually, I think his analogy works better. If the white spaces and black marks are the same width, then you are not being ANY more or less accurate by counting the odd numbers.

People seem to think that the needle falling on the black line somehow insures the BP is actually that exact number, but if it falls in a white space it's somehow less exact. Both approximations (using white space or black mark) are exactly the same accuracy. The only argument I can think of is one being better able to discern b/c of the different colored background or something neglible like that.

By reading the needle on a white space (odd numbered reading) we're not attempting to estimate seconds (going back to your clock counter-analogy), rather including other whole number readings...we're including other "minutes" that you'd be leaving out otherwise.

This is logic people...

[Thunderchild145]

Right. It doesn't matter. Just most people prefer BP to be written in even numbers. Some places require it. You do your thing, and I'll keep doing mine. :wink:

[PRPGfirerescuetech]

This is logic people...

Where you missed my point is this. There is no standard to logic.

PRPG

[BushyFromOz]

This thread should be prescribed reading to insomniacs who dont respond to strong drugs.. :shock:

[nbsp]

I think this whole discussion might have been avoided if someone had said this:

The use of even numbers is not necessarily more accurate, but is rather user convention.

It's like spelling. Lots of words are spelled funny, especially in the english language (e.g., "weight"), but regardless, the standard is stuck to.

Ever since I was first told that BPs should be reported in even numbers, I've been scratching my head as to why, but the fact remains that this user convention exists, and it's not going away any time soon. If you record a BP in odd numbers, even if you have a really good reason, you'll most likely be unfairly judged.

So, even though it doesn't make sense, it's just the way it is.

[AnthonyM83]

I thought I said that...or at least what I was trying to in my earlier posts.

[nbsp]

Then woops, my bad.

On a side note, if you round to the nearest even number, how many significant figures would it have? Would 120 have 3 significant figures or 2 or 2.5?

[AnthonyM83]

Then woops, my bad.

On a side note, if you round to the nearest even number, how many significant figures would it have? Would 120 have 3 significant figures or 2 or 2.5?

If we were using only the black (even) marks (cough, that also don't have numbers written in except for every 20mmHg), your equipment has markings to 2. mmHg place (aka 002. place), so you'd read it to the nearest .2 mmHG place. The last digit would be counted as your "uncertain." I guess you'd then round based on that last digit using regular sig fig rounding rules, making the 2nd to last number either go up on or stay where it is and your uncertain goes away.

I wouldn't actually follow all the rules of sig figs in actual practice, though...b/c the systolic is usually a 3-digit number and the diastolic a 2-digit and you it'd just be too inaccurate (not useful) of a number that you'd get at the end.

[fiznat]

I report my (manual) blood presures in both even and odd numbers, without regard for this "accuracy" argument. This is not a question of significant figures, it is a matter of convention. To hell with the nurse that tells me a systolic of 144 is more accurate than a systolic of 145. Non-invasive blood pressures are estimations anyways. I feel that it would actually be LESS accurate to argue that the BP is more accurate than it actually is! One point in BP is not significant to TREATMENT, and thats what really matters.

To the guy who said that 1mmHG of BP matters because of his "100 systolic" cutoff for NTG: :violent1: