- Primary hypertension in adults aged 18 years and older is defined as blood pressure of 140/90 mm Hg or more, based on an average of two or more properly measured seated blood pressure (BP) readings at each of two or more clinic visits.
- Normal BP is a systolic BP (SBP) <120 mm Hg and diastolic BP (DBP) <80 mm Hg.
- Prehypertension is defined as an SBP of 120–139 mm Hg or DBP of 80–89 mm Hg.
- Stage 1 hypertension is defined by an elevation in either SBP 140–159 mm Hg or diastolic BP of 90–99 mm Hg.
- Stage 2 hypertension is defined by an elevation in either SBP of ≥160 mm Hg or DBP of ≥100 mm Hg.
- The level of BP alone is inadequate for diagnosis and it should be interpreted in the context of the overall cardiovascular risk of the patient, which is most easily estimated by evaluating other concomitant disorders and target-organ damage (TOD).
Hypertension affects more than 29% adult Americans and is the most common reason for office visits to physicians in the United States. The prevalence of hypertension is expected to increase largely due to the epidemic of obesity and the aging population in the United States. Indeed, data from the Framingham health study suggest that people with a normal BP (<120/80 mm Hg) at 55 years of age have a 90% lifetime risk of developing hypertension. Additionally, it is now well established that a linear relationship exists between BP and risk of cardiovascular events, thus the more elevated the BP the greater the likelihood of myocardial infarction, congestive heart failure, kidney failure, or stroke.
Despite the increased prevalence of hypertension and its associated morbidity and mortality, current control rates are inadequate. Only 34% of people with hypertension have their BP controlled to a goal of BP < 140/90 mm Hg. Key factors for the inadequate BP control include failure of physicians to prescribe (1) lifestyle modifications, (2) adequate doses of antihypertensive medications, and (3) appropriate drug combinations and increased occurrence of pure systolic hypertension in the elderly, which is considerably more difficult to treat.
The Joint National Committee (JNC) 7 recommends that specific public health interventions such as decreasing calories, saturated fat, and salt intake, especially in processed foods, and increasing physical activity be strongly encouraged at school and community levels. This strategy can achieve a downward shift in the distribution of a population's BP and thus potentially decrease the lifetime risk of morbidity and mortality from hypertension in an individual.
Measurement of Blood Pressure
Accurate measurement and interpretation of BP is crucial for the diagnosis and treatment of hypertension. The recommendations outlined below will help standardize the technique and improve the accuracy of BP readings:
- Patients should abstain from drinking caffeine or alcohol-containing beverages or using tobacco within 30 minutes prior to a BP measurement.
- The cuff size appropriate for the patient's arm circumference should be used (the cuff bladder should encircle at least 80% of the arm).
- The cuff bladder should be centered over the brachial artery, with its lower edge within 2.5 cm of the antecubital fossa.
- Listen over the brachial artery using the bell of the stethoscope with minimal pressure exerted on the skin. Inflate the cuff 20 mm Hg higher than the pressure at which the palpable pulse at the radial artery disappears. Use a properly calibrated syphgmomanometer.
- The deflation rate of the column of mercury should be 2–3 mm Hg/second.
- Multiple measurements should be made on different occasions in the sitting ...