What is High Blood Pressure and hypertension?

Blood pressure (BP) levels are continuously related to the risks of cardiovascular disease (CVD). The definition of hypertension or raised Blood Pressure is therefore arbitrary. Even within the normotensive range, people with lowest levels of Blood Pressure have the lowest rates of cardiovascular disease.

Because Blood pressure is characterized by large spontaneous variations, the diagnosis of hypertension should be based n multiple Blood Pressure measurements taken on several separated occasions.

Classifications and definitions of High Blood Pressure

Category	Systolic BP (mm/Hg)	Diastolic BP (mm/Hg)
Optimal BP	<120	<80
Normal BP	<130	<85
High-Normal BP	130-139	85-89
Grade 1 Hypertension (mild)	140-159	90-99
Grade 2 Hypertension (moderate)	160-179	100-109
Grade 3 Hypertension (severe)	>180	>110

When a patient's systolic and diastolic blood pressures fall into different categories, the higher category should apply.
In some patients, office (or clinic) blood pressure is persistently elevated whereas daytime BP outside clinic environment is normal. There is counting debate as to whether "isolated hypertension ("white coat hypertension") is an innocent phenomenon or whether it carries an increased burden of cardiovascular risk.

Clinical evaluation - what should be done?

Information for medical personal
The clinical and laboratory evaluation of hypertensive patient should be conducted with four aims:

1. to confirm a chronic elevation of blood pressure and determine the level
2. to exclude or identify secondary causes of hypertension
3. to determine the presence of target organ famageand quantify its extent
4. to search for other cardiovascular risk factors and clinical conditions that may influence the prognosis and treatment

Blood pressure should be measured several times on several occasions with the patient in a sitting position using a mercury sphygmomanometer or other non-invasive device. The accuracy of non-mercury devices should be ensured by periodic comparison with values simultaneously obtained from a mercury sphygmomanometer. Use the following procedures when recording BP:

• Allow the patient to sit for several minute before measuring blood pressure
• Use a cuff with a bladder that is 12-13 cm x 35 cm, with a larger bladder for arms
• Use phase 5 Korotkoff sounds (disappearance) to measure the diastolic pressure
• Measure the blood pressure in both arms at first visit
• Measure the BP in standing position in elderly subjects and diabetics patients
• Place the sphygmomanometer cuff at heart level, whether the position of the patient

Minimum routine investigations

• Clinical and family history
• Full physical examination as described in medical textbooks
• Laboratory investigations, including:
1. Urinalyses for blood, protein. And glucose
2. Microscopic examination of urine
3. Blood chemistry of potassium, creatinine, fasting glucose, and total cholesterol
• Electrocardiography

Further investigations should be guided from the history, examination, and routine investigations

Situations in which ambulatory blood pressure monitoring should be considered:

• Unusual variability of blood pressure over the same or different visits
• Office ("white coat") hypertension in subjects with low cardiovascular risk
• Symptoms suggesting hypotensive episodes
• Hypertension resistant to drug treatment

Blood pressure values obtained by home measurement or ambulatory monitoring are several mm Hg lower than those obtained by office measurement with average 24 hour or home BP values around 125/80 mm/Hg corresponding to office BP of 140/90 mm Hg. Reliable information about the long-term prognostic value of ambulatory and home BP monitoring is awaited.

References:
1999 WHO/ISH Hypertension Guidlines