On February 27th, classmate Bruce Alpert, MD led us in a Casual Conversation about the importance of proper measurement of blood pressure. Here is the core document he shared as part of the event. All of us should read it, and perhaps bring a copy with us to our medical appointments to share with our clinicians:
THE IMPORTANCE OF ACCURATE BLOOD PRESSURE VALUES
BP is the most important of the “vital signs.” BP and weight are the most critical in how long you live. Try to lower BOTH in any ways you can. Recent American Heart recommendations state that “ideal” BP is 120/80. The top number is called the Systolic, the lower number Diastolic. Mild hypertension is 130, more serious at 140. In the old days 140 was thought to be only mild hypertension. These numbers are for resting/baseline BP.
The rules for patient positioning/preparation to achieve resting state are as follows:
1. Sitting in a chair for at least 4-5 minutes.
2. NO TALKING.
3. Back supported.
4. Arm with BP cuff supported at the level of the heart.
5. Feet flat on the floor.
6. Largest BP cuff that will fit on upper arm; too small a cuff will increase BP reading.
7. Cuff on bare skin, NOT OVER CLOTHING.
If the person doing the BP on you tells you to climb up on the exam table for readings DON’T DO IT!!! On the exam table numbers 3,4,5 above CANNOT BE ACHIEVED.
There are some automated devices for professional or home use which try to determine BP at the wrist. DO NOT TRUST YOUR HEALTH TO THESE. Do not believe what your watch or smart phone says your BP reading is. These devices have NOT been validated against gold standard BP values prior to release. A helpful resource to guide you in the purchase of a home device is the AMA’s Validated Device List (validatebp.org) which I co-wrote with other experts. It lists many of the devices which have undergone proper validation testing. Manufacturers are still submitting their products for inclusion. There are other listings which allow manufacturers to buy their way onto the recommended list.
The OPTIMAL way to choose a home BP device is to buy the one that looks good on the pharmacy shelf and take it to your MD’s office. Take readings with that device and alternate readings using WHATEVER MEANS YOUR MD USES TO MAKE CLINICAL DECISIONS. Hopefully the office uses properly done manual auscultation, but don’t count on the proper part. Automated devices use a different technology, oscillometry, to estimate BP. Notice I did NOT SAY MEASURE BP. The devices utilize a computer algorithm to estimate BP over a very large range of values. Every manufacturer has a different proprietary algorithm, so every BP device will give a different BP estimation. The validation protocol (ISO 81060-2) requires BP’s <100 Systolic to >160 for at least 85 people. I currently Chair the ISO Committee which writes and updates the ISO Standard.
YOU are in charge of ensuring your BP values in your medical record are correct; do NOT trust the “nurse” assigned to obtain those values to have your best interest. They may want to keep the MD happy by doing vital signs QUICKLY and getting you to see the MD without delay. Inaccurate BP values can result in TREATMENT FOR HYPERTENSION WHICH YOU DO NOT HAVE OR LACK OF TREATMENT FOR HYPERTENSION YOU DO HAVE.