How to Read a Blood Pressure Cuff

Blood pressure (BP) is the force exerted by the amount of blood pushing against the walls of the arteries. Taking the blood pressure involves measuring two numbers, the systolic pressure and the diastolic pressure. Systolic pressure is the highest arterial pressure when the heart beats while pumping blood; diastolic pressure is the lowest arterial pressure when the heart is relaxed before it begins contracting again. Blood pressure recordings are presented in a way where systolic pressure is written above the diastolic pressure. Blood pressure cuff or sphygmomanometer is the apparatus used to detect blood pressure, and is by far, the most commonly used among all monitors. It is operated manually and its parts include an arm cuff, a rubber inflating bulb with an attached air valve, a built in stethoscope used for auscultation (not all models have a stethoscope, sometimes you have to provide it separately), and a dial gauge. The dial gauge has a pointer that moves clockwise when the cuff is inflated, and counterclockwise when the cuff is deflated, which then provides you the numbers for your blood pressure reading.

Things You'll Need

• Stethoscope
• Sphygmomanometer

Instructions

1. Allow the patient to sit or lie comfortably on a chair or bed for at least 3 minutes before taking the blood pressure. After a few minutes of rest, let the patient supinate (palms facing up) one arm to expose the brachial artery located on the inner side of the shallow crease between the forearm and the upperarm (cubital fossa). Make sure that the arm is of the same level as the heart and is properly rested on the table or on the bed.

2. 

   Place the cuff above the area of the brachial artery which is about 1 inch on top of the crease of the arm (cubital fossa). If you are using sphygmomanometer with a built-in stethoscope, you can position the cuff on the very area of the brachial artery.

3. Secure the cuff by closing the Velcro strap snugly around the upper arm. Do not close it too tight or it may hinder the accuracy of your reading. You can check to know if you are wrapping it just right by slipping one finger in the space between the cuff and the upper arm. If your finger slips in easily, that means you are doing it right. But if you are not able to slip your finger in between, that’s a cue that you have to adjust the tightness of the cuff.

4. 

   Put the earpieces of the stethoscope in your ears and position its disk on the area of the brachial artery which is slightly above the inner side of the cubital fossa or the crease between the forearm and the upper arm. Secure the disk by holding it with your thumb or fingers.

5. Lock the air valve of the inflating bulb and then squeeze the bulb rapidly to inflate the cuff. As you do this, pay close attention to the pointer of the dial gauge. When the pointer reaches 150, you can stop pumping air on the cuff.

6. 

   Loosen the air valve gradually to deflate the air off the cuff. As you are doing this, pay close attention to both the sound in your stethoscope and the pointer of the dial gauge. Do not deflate the cuff too fast or you may not hear the sound of the pressure. Just do it gradually at about 2 to 3 mm hg per second.

7. Listen to your stethoscope and watch the pointer of the dial gauge as it moves counterclockwise when you deflate the cuff. In a few seconds, you will hear a pulsing sound on your stethoscope. The pointer of the dial gauge will slightly jerk on a particular number at the same time you hear the first sound. Such sound is coming from the blood rushing through the arteries after opening the closed brachial artery -- this is known as the systolic pressure.

8. 

   Continue to deflate the air valve gradually and still keep an eye on the pointer of the dial gauge. The sound in your stethoscope will slowly fade until you can’t hear it anymore. Note where the pointer of the dial gauge is leveled after you hear the last sound. This will be the diastolic pressure.

9. Let all the remaining air out of the cuff. Record the blood pressure of the patient with the systolic pressure written above the diastolic pressure for example: 120/80 (120 as the systolic and 80 as the diastolic).

Tips & Warnings

• Be aware of some abnormal blood pressure readings to detect signs of an overly high or overly low blood pressure:

• • Pre-high blood pressure is indicated when the systolic pressure is 120 to 139 and the diastolic pressure is 80 to 89.

• • A sign of hypertension is indicated when the systolic pressure is as high as 140 and above, and the diastolic pressure is 90 and above.

• • An indication of hypotension or low blood pressure is noted when the systolic pressure drops to 100 and the diastolic pressure drops to 60. There are individuals who still feel normal with this blood pressure. But if such blood pressure is accompanied with lightheadedness and having the urge to vomit, contact the doctor right away.

• Always check your blood pressure equipment to ensure an accurate result. A small puncture on the surface of the tubing or a dysfunctional dial gauge, will largely affect the overall result of your reading.

• The patients’ arm should always be leveled to the heart when taking his/her blood pressure. An arm lower than the level of the heart may result to an inaccurate high blood pressure reading; and an arm positioned higher than the heart level may result to an inaccurate low blood pressure reading.