What a blood pressure measurement is in reality

Seems a bit daft to post on this subject, but I struggled to find anything out on the web about what the numbers actually represent. There’s plenty of stuff telling you what values are high, normal etc. but nothing about what is actually happening during the course of a measurement. But I found some documentation eventually, looks like it is aimed at clinicians, which I’ll try to explain.

You wrap the cuff around your upper arm. At that point, you’re over your brachial artery, so a direct route to the heart. The documentation I looked at made a big deal of this, so this is important.

The cuff inflates sufficiently high that it stops blood flowing. If you were listening with a stethoscope, you’d hear nothing.

You gradually let the pressure out of the cuff. Your heart pumps with sufficient pressure that, sooner or later, it overcomes the pressure in the cuff, and the blood starts flowing again. Again, if you had a stethoscope, you’d hear the heart beating. When blood first starts flowing, this is the systolic blood pressure – the pressure when the heart beats.(

You keep releasing pressure from the cuff. You can still hear the heart beating. Again, sooner or later, you stop hearing anything. At that point, this is the diastolic blood pressure. Basically the pressure in the cuff is sufficiently low that your heartbeat can’t be heard. It’s the pressure when your heart is resting. In my simple world, I think of the heart as a machine which is either on (pumping) or off (resting). In this scenario, at any rate.

I mean, a stethoscope is just one way of detecting these signals. I would imagine an electronic machine would detect these points by “feeling” when the pulse starts and stops (a momentary slight increase in pressure, say, as the heart pulses). I think my next task is to find this out.

I’ve tried to explain this briefly and in layman’s terms. If you feel i could do better, please leave a comment, or there’s a link at the bottom of the page which you can use to contact me.

People’s knowledge of diabetes

We went over to see my mother-in-law at the weekend. We also met up with my sister-in-law while we were over there. It was funny that, for both of them, a lot of their knowledge of diabetes was just plain wrong.

I mean, nothing against them. Neither of them has diabetes, certainly not to the extent where they’re shoving meds into their body to control their sugar, so why should they be expected to know about something they don’t have?

But it was interesting that they have picked up their (mis)knowledge from the media, and a lot of that is just wrong. There is an implicit assumption that diabetes is about sugary food, whereas it is carbs in general. Sure, sugar is carb, but a portion of bread might have every bit as much effect on my sugar. I know, because I measure it. And there’s a hereditary link, it’s not just down to lifestyle. I know this because much of my father’s family have it, too. In fact, I can tolerate a bit of chocolate every now and again, a 50g bar every week or so, and it doesn’t raise my  sugar noticeably. Certainly not as much as if I have hot dogs/rolls for lunch.

But it really gets my goat that the media continually spreads this misinformation. I’ve even argued online with somebody who’ve said to me, “change your diet and you’ll reverse your diabetes”. And I can stop taking insulin, just like that. Actually it made me have a stroke, smartass.