Making A Diagnosis Of Hypertension

To make a diagnosis of hypertension, a health care professional must obtain a blood pressure measurement during a routine clinical examination. Usually, the patient sits down and rests their arm on a table so the brachial artery is level with the heart. A sphygmomanometer (also known as a sphygmometer or blood pressure meter) is a device used to measure blood pressure.

A typical sphygmomanometer (pictured) consists of:

• an inflatable cuffM
• a measuring unit known as the mercury manometer and,
• an inflation bulb.

The inflation bulb usually has an adjustable valve to prevent a leak of pressure and to reduce the pressure in a controlled manner. A tube usually connects the bulb to the cuff. Another tube connects the cuff to the mercury manometer (calibrated in millimeters of mercury mmhg). Manual sphygmomanometers are usually used together with a stethoscope.

The cuff is usually placed around the upper left arm (midway between the shoulder and the elbow) and inflated by depressing the inflation bulb repeatedly. Ensure that the mercury column is at zero before inflating. The cuff is inflated until the artery in the elbow, known as the brachial artery, is completely occluded. A healthcare professional will listen with a stethoscope over the brachial artery while slowly releasing the pressure in the cuff. The pressure in the cuff is reduced by opening the valve in the inflation bulb.

As the pressure in the cuff falls, popping or pounding sounds are heard over the stethoscope. These sounds are known as korotkoff sounds (named after the Russian physician who first described these sounds). The sounds are heard as blood slowly fills the partially compressed artery.

The level of pressure in the cuff (observed by reading the mercury column) when the first korotkoff sound appears is known as the systolic pressure. The level of pressure in the cuff when the korotkoff sounds disappears, or is muffled, is known as the diastolic pressure. Values obtained are read as systolic bp/diastolic bp in millimeters mercury (mmhg) for example 120/90mmhg.

Over the last 30 years, technology for obtaining accurate and consistent blood pressure measurements have improved considerably. The blood pressure meters available today are:

1. Mercury (described above) - considered by many to be old fashioned but still remains the gold standard for measuring blood pressure levels. Still widely used within and outside the traditional medical environment.

2. Aneroid- makes use of a mercury manometer and has to be calibrated regularly to obtain accurate results. Portable and non portable versions are available.

3. Digital/electronic monitors- are useful for home bp monitoring. They are inexpensive and tend to increase patients interest in blood pressure management. It is particularly useful for persons with hearing disabilities, bedridden patients being managed at home and persons having difficulties with coordination. However, accuracy varies between patients.

It is important to note that certain factors may affect blood pressure measurement. These include:

• recent food intake
• recent ingestion of alcohol
• recent intake of caffeine - containing beverages
• recent intake of prescription medication for example steroids and oral contraceptive drugs
• cigarette smoking
• recent exercise
• constipation
• a full bladder
• adopting an incorrect posture.