Heart to Heart conversation: The Basics of Blood Pressure
First, I must state my belief that the best way to measure blood pressure is to do-it-yourself on a regular basis. Many people simply rely on blood pressures done in the doctor's office or in the hospital. However, most people know that some people have what is called "white coat hypertension" which refers to high blood pressure in the doctor's office. This is because they are stressed or trying to remember things that they have heard or need to say. Also, in many settings, patient's blood pressures are not done sitting for 5-10 minutes.
Blood pressure can vary quite a bit from minute to minute and day to day. When people are moving, their blood pressure goes up. Therefore, it is important to be sitting for at least 5-10 minutes before doing the blood pressure if the goal is to assess whether the blood pressure is under good control. Our standards for blood pressure control and largely related to sitting blood pressures (not lying down or standing) and because of the known effect of moving, most studies on blood pressures to set up normals or see about drug effectiveness are done after the patient has been sitting for 5-10 minutes.
The advantage of the patient doing their own blood pressure is that they can have more readings to know how their blood pressure varies under certain conditions. For example, some patients may have much higher blood pressures at work or conversely the blood pressure may be low 3-4 hours after medication has been taken for blood pressure. So it is very important to understand the variation within the day or the variation that occurs on weekdays versus weekends to avoid overtreating or under treating blood pressure. This simply cannot be done in the doctor's office (although there are special devices that can be used to monitor the blood pressure for 24 hours at a time called ambulatory blood pressure monitors).
Besides sitting for 5-10 minutes, the other important factor in the home measurement of blood pressure is that the cuff must be placed at heart level. Heart level is roughly breast level and is usually correct if the bottom of the cuff is placed 1/2 inch to an inch above the elbow and the patient is sitting in a high back chair with the feet on the floor. One of the problems with wrist and finger cuffs is that they may be measuring above or below heart level if held incorrectly.
The home blood pressure cuffs measure the pulse wave as it comes down the arm. So it should be placed on the bare arm. Most cuffs have directions on placing the cuff so the detector portion is over the inside of the arm where the artery is located.
My two preferred blood pressure cuffs are Omron and LifeSource. Important features are automatic inflation by pushing one button, memory to store up to 30 measurements and battery and an AC adapter. All monitors mentioned also are good for irregular heart beats which can cause problems with other monitors. All these monitors have what is called “artificial intelligence” that lets them inflate to the appropriate blood pressure and detect the blood pressure even with an irregular heart rhythms.
LifeSource has a cuff they call the "Easy Cuff". This cuff is 2 inches larger than the standard medium cuff to fit more arm sizes. Omron has a similar cuff called the "Comfit" cuff. However, if you have a very large arm or a very thin arm you may need a different size cuff. Typically, insurance will not cover the cost of a blood pressure cuff and monitor -- for reasons that I don't understand. Prices for the monitor, cuff, adapter typically range from $30-65 with the features noted. Options include online, big box stores, smaller stores or pharmacies. Monitors and cuffs over $70 may have features you do not need or may be overpriced.