Blood Pressure Measurement

 Blood Pressure Measurement

Blood pressure is the force exerted by blood against the walls of arteries and veins. It is created by the pumping action of the heart. Blood pressure is measured in millimeters of mercury (mm Hg) and is expressed by two numbers—120/80, for example. The higher number is systolic blood pressure, the maximum pressure that occurs when the heart contracts. The lower number is diastolic blood pressure, the pressure when the heart is relaxed between contractions.

 Equipment

1. Sphygmomanometer (A sphygmomanometer consists of an inflatable bag inside a covering called a cuff, an inflating bulb, a manometer from which blood pressure can be read, and a valve that is used for deflation.)

2. Stethoscope

3. Chair

4. Table or another surface to support arm

Sphygmomanometer

Preparation

For the person being tested: Wear clothing that allows your upper arm to be bare. Avoid heavy exercise or eating prior to the test. Don’t smoke or ingest caffeine for at least 30–60 minutes before being tested. Sit quietly for several minutes before the test begins.

 

Instructions

1. The subject should sit comfortably, with the arm slightly flexed, palm up, and the forearm supported at  heart level on a table or other smooth surface. If such a surface isn’t available, you will need to support the subject’s forearm while you take the measurements.

2. Place the deflated cuff on the subject’s upper arm, with the lower edge of the cuff about 1 inch above the inner elbow crease. The inflatable bag should rest on the brachial artery, which is on the inner part of the upper arm. The inflatable bag should encircle at least 80% of the arm; if it does not, use a larger sphygmomanometer.

3. Apply the stethoscope lightly to the arm, just at the inner elbow crease. Make sure the stethoscope doesn’t touch the cuff or any of the tubing from the sphygmomanometer.

4. While watching the manometer and listening for pulse sounds through the stethoscope, inflate the bag about 30 mm Hg above the point at which pulse sounds disappear. (Inflating the bag closes off the blood flow in the brachial artery, causing the pulse sounds to stop.)

5. Slowly deflate the bag at a rate of about 3 mm Hg per second (or per heartbeat). As you release the pressure, pulse sounds will become audible, go through several changes in clarity and intensity, and then disappear again. You must listen carefully to the pulse sounds while you watch the readings on the manometer.

• Systolic pressure is the point at which pulse sounds first become audible. You should hear faint but clear tapping sounds.

• Diastolic pressure is the point at which the pulse sounds disappear.

 

Blood Pressure Classification Average the results of the two sets of measurements. Refer to the table below for the rating.

 

Average pressure: _______ / _______ Classification: ____________________

 

(systolic)                        (diastolic)

 Categorya                     Systolic (mm Hg)                                        Diastolic (mm Hg)

Normalb                        Below 120                     and             Below 80

Prehypertension             120–139                        or                80–89

Hypertensionc Stage 1 140–159 or 90–99 Stage 2 160 and above or 100 and above

 

Result: Blood pressure of  own/ person is ------ (mmHg) Systolic -------  (mmHg) Diastolic  mmHg.