How to Figure the Mean of a Blood Pressure Reading

One of the vital signs routinely taken on every visit to a physician is blood pressure. This is an indicator of how hard the heart is working to get blood to all of the body and how much resistance arteries and veins are placing on the flow of blood. If the heart is working too hard or the blood vessels are narrowed because of cholesterol deposits, blood pressure is affected. The mean arterial blood pressure (MAP) is a measure of the average blood pressure of an individual and used as a standardized way to diagnose or treat high blood pressure (hypertension). 

 

Things You'll Need

• Blood pressure cuff
• Stethoscope
• Paper pad
• Pen or pencil
• Calculator

Instructions:

Reading the Blood Pressure

1. Place the blood pressure cuff over the patient's arm, inflating it slightly to keep it in place right above the elbow. Have the patient be still for the remainder of the procedure.

2. Place the stethoscope over the crease of the elbow and listen for the beating sounds of the brachial or radial arteries, which run through the crease of the elbow.

 

3. Inflate the cuff to the point where you no longer hear the artery beating.

 

4. Release the air from the cuff steadily, writing down the pressure readings from the pressure dial on the cuff when you begin to hear the artery beating again. That is the systolic blood pressure reading in millimeters of mercury (mmHg). Then write down the reading from the pressure dial when you stop hearing it as a result of no pressure being placed on the artery. This is your diastolic reading.

Calculate Mean Arterial Blood Pressure

5. Make sure the patient was at rest throughout the blood pressure reading. Any increases in pulse due to activity or exercise negate the mean arterial blood pressure reading.

 

6. Subtract the diastolic reading from the systolic reading. This is product A.

 

7. Multiply product A by 0.33. This is product B.

 

8. Add the diastolic reading to product B. This is the mean arterial blood pressure reading.

Tips

• The formula for mean arterial blood pressure (MAP) is: MAP= Diastolic + 0.33(Systolic - Diastolic). This is only an approximation to MAP in a patient at rest. For a more precise reading, the patient might need to visit a cardiac laboratory or a cardiologist's office for measurements with more complicated instruments.
  

  Warnings

• Never self-diagnose and treat hypertension. Only a licensed health care provider should diagnose and treat you for hypertension or any other condition. If you find your blood pressure to be elevated, or are worried about having high blood pressure, consult your health care provider. There are plenty of treatments and lifestyle changes that he or she can offer to effectively treat or prevent hypertension.