Hi I'm Dr. Margaret Collins-Hill with Consults in Hypertension in Wilmington, North Carolina. The question this evening is how to calibrate a blood pressure cuff. Making sure that your blood pressure machine is accurate is very important because small differences can make a difference in what medications may be adjusted. Most people when they have a home machine it's very much like this one, an electronic device. These are much easier to use when you like to measure your blood pressure yourself. Generally the cuffs have Velcro that you can close over your arm with one hand and all you have to do to measure the blood pressure is to press the button, that's all you need to do. In doctor's offices we use a manual device like this aneroid wall unit right here. In this case you need special training and generally another person to measure blood pressure. The cuff goes around the arm in the same way but you have to listen over the artery to have the pulsations come and go to know what the blood pressure readings are. When we talk about calibrating a device it implies zeroing out a scale or actually changing the machinery. This isn't really what we do with these devices. In my hypertension clinic I have my patients bring their home machine in on several different visits and we make readings from their home machine and then against the wall unit at the same time under the same circumstances. It's o'kay if these units vary. What you want is consistency. I would rather have a blood pressure machine that reads ten points high every time rather than one that reads perfectly but not every time. When you're checking your blood pressure at home you want to be sure and follow proper technique and write down all of the values that you obtain. Having values from different times of day and different circumstances will help your doctor adjust your medications both in dose and in timing. If you're worried about your blood pressure machine bring it in and have your doctor check it against the manual device. In general you can buy these machines over the counter without much difficulty between $30 and $100. In general the wrist machines and finger machines are more expensive and less accurate so it's better to choose one with an arm cuff. You also need to be sure that the arm cuff fits you properly because in particular if the cuff is too small you'll get a high reading. When you're getting a blood pressure reading you also want to hold your arm at the level of your heart. If you're not sure where that is think about the pledge of allegiance. Lay your hand over your heart and then raise your other arm so they're equal, that's the position you want to be in. If your arm is lower blood is running downstream and you'll get a high reading. Similarly you can't raise the arm and cheat. So to recap to calibrate your blood pressure cuff is really to measure against another source of blood pressure measurement to be sure that they match reasonably and that the blood pressure readings are consistent. Be sure that you get a good machine, try to get one with an arm cuff and make sure it fits. If you have any questions, bring your machine to several visits to see how the consistency holds up.