Is A Manual Blood Pressure More Accurate?

Reviewed on 5/24/2021

Manual blood pressure readings

Manual blood pressure gives accurate results when used correctly by a trained person. However, manual blood pressure measurement is not the recommended type of blood pressure monitoring for home use because it requires some training.
Manual blood pressure gives accurate results when used correctly by a trained person. However, manual blood pressure measurement is not the recommended type of blood pressure monitoring for home use because it requires some training.

Manual blood pressure gives accurate results when used correctly by a trained person. However, manual blood pressure measurement is not the recommended type of blood pressure monitoring for home use because it requires some training. Some of the common causes include

  • Inappropriate cuff size (too small or too large)
  • Failure to reduce patient anxiety
  • Uncalibrated instrument
  • Interaction between patient-clinician

A study has shown that automated blood pressure monitors seem to provide inaccurate readings in 5 to 15 percent of people. The study has also stated that the varying blood pressure can be a result of several factors. However, due to its obvious advantages, it is the best choice among many people.

What are the different types of blood pressure monitors?

Two types of blood pressure monitors are

  1. Manual
  2. Automated/digital

Manual blood pressure monitors

Different types of manual blood pressure monitors are

  • Mercury: This consists of a cuff that wraps around the arm, a rubber squeeze bulb and a mercury column that measures the blood pressure. A stethoscope is required to listen to the blood pounding through the artery. The blood pressure can be seen on the mercury column as the mercury moves up and down when the pressure in the cuff rises or falls. Mercury blood pressure monitors were a gold standard to monitor blood pressure until recently. However, due to the increased environmental hazard with mercury, doctors are slowly replacing this blood pressure monitor with aneroid or automated ones.
  • Aneroid: This consists of a cuff that wraps around the arm, a rubber squeeze bulb and a gauge that measures the blood pressure. A stethoscope is required to listen to the blood pounding through the artery. The blood pressure can be seen on a circular dial of the gauge as the needle moves around and the pressure in the cuff rises or falls.
  • Electronic blood pressure machine: This is similar to a mercury instrument. Instead of mercury, it contains an electronic column that rises and falls. It consists of a cuff that wraps around the arm and a rubber squeeze bulb. A stethoscope is required to listen to the blood pounding through the artery.

Automated blood pressure monitors

This involves an electronic device that will also have a cuff that wraps around the arm. To inflate the cuff, either use a rubber squeeze ball or a push-button, depending on the device.

Once the cuff is inflated, the pressure drops automatically. The screen will show digital readings of the systolic and diastolic blood pressure.

Once the screen shows the reading, the cuff will deflate on its own. Before repeating the measurement, wait for two to three minutes. Digital monitors are the best choice for most people.

Table. Advantages and disadvantages of manual and automated blood pressure monitors

Type of blood pressure monitor            Advantages       Disadvantages          
 Manual  
  • Most accurate in hands of trained personnel
  • Good for confirming hypertension
  • High chances of observer error
  • Noise interference can result in inaccurate  readings
  • Small movements can cause inaccurate  readings
  • Difficult to monitor in infants or small children
  • Mercury can cause an environmental hazard
  • Aneroid loses its accuracy over time
 Automated
  • Ease of use
  • Good for screening
  • Home use
  • Used in infants or small children
  • Repeated measurements possible
  • Not affected by cuff placement
  • Wrist cuff available
  
  • First measures mean arterial pressure then calculates systolic and diastolic blood pressure
  • Differences in machines depending on the manufacturer
  • Vibrations
  • Irregular heart rate can give inaccurate readings

How to get the most accurate reading with automated blood pressure monitors

To get an accurate reading

  • Avoid smoking, caffeinated or alcoholic beverages 30 minutes before the test.
  • Sit straight for five minutes with the back well supported and feet on the floor.
  • During the measurement, support the arm so that the elbow is at the level of the heart. For example, placing the arm over a dining table if sitting on a chair.
  • Always wrap the cuff on bare skin and pull up the sleeves, if necessary.
  • Read the instructions carefully and measure the blood pressure according to the instructions. Leave the deflated cuff in place, wait a few minutes and then take a second reading. If the measurements are close, average them. If not, repeat and average the three readings.
  • Don’t get overwhelmed with a high reading. Relax for a few minutes and try again.
  • Keep a record of blood pressure readings and the time of recording.

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References
Medscape Medical Reference

BCMJ


Harvard Health Publishing


Adolescent Health, Medicine and Therapeutics


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