Blood Pressure Formula

About 1 in 3 adults in the United States has high blood pressure (HBP or hypertension), which increases the risk for heart disease and stroke, the first and third leading causes of death in the United States.[1] Persistent high blood pressure is also a leading cause of chronic kidney failure.[2] Even moderate elevation of arterial blood pressure leads to shortened life expectancy. Beginning at a systolic pressure of 115 mmHg and diastolic pressure of 75 mmHg (written as 115/75 mmHg), cardiovascular disease risk doubles for each increment of 20/10 mmHg.[3]

High blood pressure itself usually has no symptoms. You can have it for years without knowing it. During this time, it can damage the heart, blood vessels, kidneys, and other parts of the body. This is why knowing your blood pressure numbers is important, even when you're feeling fine.

Classification
The table below shows blood pressure criteria for defining normal blood pressure, pre-hypertension, hypertension (stages I and II). The ranges in the table apply to most adults (aged 18 and older) who don't have short-term serious illnesses. Patients with blood pressures over 130/80 mmHg along with Type 1 or Type 2 diabetes, or kidney disease require further treatment.[3]

High blood pressure can be classified as either primary or secondary. Primary hypertension means that no medical cause can be found to explain the raised blood pressure and represents about 90-95% of hypertension cases.[4][5][6] Secondary hypertension indicates that the high blood pressure is a result of another condition, such as kidney disease or tumors.

Signs and symptoms
Mild to moderate primary hypertension usually has no warning signs or symptoms. Severe hypertension is associated with headache, somnolence, confusion, visual disturbances, and nausea and vomiting. Retinas are affected with narrowing of arterial diameter, copper or silver wire appearance, exudates, hemorrhages, or papilledema.

Common Causes
While the most prevalent (90-95% of cases) hypertension type - primary hypertension - has an unknown cause, there are many factors such as sedentary lifestyle, stress, visceral obesity, potassium deficiency (hypokalemia), obesity (more than 85% of cases occur in those with a body mass index greater than 25), salt (sodium) sensitivity, alcohol intake, and vitamin D deficiency. High blood pressure risk also increases with aging, some inherited genetic mutations and family history.

Secondary hypertension by definition results from an identifiable underlying secondary cause. It is much less common than primary hypertension, affecting only 5% of cases. It has many different causes including endocrine diseases (such as Cushing's syndrome - an excessive secretion of the hormone cortisol by the adrenal glands), kidney diseases, and tumors. It also can be a side effect of many medications.

Treatment
Lifestyle Modifications
The process of managing hypertension according the guidelines of the British Hypertension Society suggest that non-pharmacological options should be explored in all patients who are hypertensive or pre-hypertensive. Lifestyle changes such as the DASH (Dietary Approaches to Stop Hypertension) diet, physical exercise, and weight loss have been shown to significantly reduced blood pressure in people with high blood pressure.[7] If hypertension is high enough to justify immediate use of medications, lifestyle changes are initiated concomitantly.

Medications
There are many classes of medications for treating hypertension. The aim of treatment is often to achieve blood pressure of <140/90 mmHg for most patients, and lower in certain contexts such as diabetes or kidney disease.[8] Each added drug may reduce the systolic blood pressure by 5–10 mmHg, thus multiple drugs are often necessary to achieve the desired blood pressure level.

• ACE inhibitors: captopril, enalapril, fosinopril (Monopril), lisinopril (Zestril), quinapril, ramipril (Altace)
• Angiotensin II receptor antagonists (where ACE inhibitors are not tolerated): telmisartan (Micardis, Pritor), irbesartan (Avapro), losartan (Cozaar), valsartan (Diovan), candesartan (Amias), olmesartan (Benicar, Olmetec)
• Calcium channel blockers: nifedipine (Adalat), amlodipine (Norvasc), diltiazem, verapamil
• Diuretics: bendroflumethiazide, chlorthalidone, hydrochlorothiazide (HCTZ).

References
1. CDC. Health, United States, 2008. Hyattsville, MD: National Center for Health Statistics; 2008.
2. Pierdomenico SD, Di Nicola M, Esposito AL, et al. (June 2009). "Prognostic Value of Different Indices of Blood Pressure Variability in Hypertensive Patients". American Journal of Hypertension 22 (8): 842–7. doi:10.1038/ajh.2009.103. PMID 19498342.
3. Chobanian AV, Bakris GL, Black HR, et al. (December 2003). "Seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure". Hypertension 42 (6): 1206–52. doi:10.1161/01.HYP.0000107251.49515.c2. PMID 14656957.
4. Carretero OA, Oparil S (January 2000). "Essential hypertension. Part I: definition and etiology". Circulation 101 (3): 329–35. PMID 10645931.
5. Oparil S, Zaman MA, Calhoun DA (November 2003). "Pathogenesis of hypertension". Ann. Intern. Med. 139 (9): 761–76. PMID 14597461.
6. Hall, John E.; Guyton, Arthur C. (2006). Textbook of medical physiology. St. Louis, Mo: Elsevier Saunders. p. 228. ISBN 0-7216-0240-1.
7. Blumenthal JA, Babyak MA, Hinderliter A, et al. (January 2010). "Effects of the DASH diet alone and in combination with exercise and weight loss on blood pressure and cardiovascular biomarkers in men and women with high blood pressure: the ENCORE study". Arch. Intern. Med. 170 (2): 126–35. doi:10.1001/archinternmed.2009.470. PMID 20101007.
8. Shaw, Gina (2009-03-07). "Prehypertension: Early-stage High Blood Pressure". WebMD