|This narrated slideshow gives a brief overview of Hypertension & the JNC 7. It discusses both the prevalence of hypertension and the relationship between blood pressure and the risk of cardiovascular disease. It also describes the JNC 7.
The Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure attempts to provide an evidence-based approach to the prevention and management of hypertension.
In 2003, the Seventh Report of the Joint National Committee on Prevention, Detection and Treatment of High Blood Pressure was released and is also known as JNC 7. JNC 7 recommendations are based on large scale clinic trials such as ALLHAT, EPHESUS, HOPE, PROGRESS, RENAAL, among others.
The Joint National Commission issued updated hypertension guidelines in December 2013 based on more rigorous evidence, and less dependence on expert opinion, than JNC 7. JNC 8 only answers a few new questions for the primary care physician, mostly focused on hypertension treatment recommendations. Thus, JNC7 is still the final word for several elements of hypertension that JNC 8 did not address, particularly regarding screening, evaluation, diagnosis and classification of high blood pressure. The criteria for a diagnosis of hypertension are the same in JNC7 and JNC 8. This module will refer to both JNC7 and JNC 8 at different points, depending on the topic.
What is the definition of hypertension? (Choose the best answer)
The correct answer is 4. A systolic blood pressure greater than 140 or a diastolic blood pressure greater than 90. The strict definition of hypertension has not changed. There is a subcategory of normal blood pressure known as “prehypertension” that we will discuss later in the module, however this category does not lower the definition of hypertension.
How many elevated blood pressure measurements do you have to get from your patient, Mary Johnson, before you can diagnose her with “hypertension”? (Choose the one best answer)
The correct answer is 3. As per JNC 7 standards, at least two elevated measurements, one in each arm, should be made on 2 or more visits. Diagnosing a patient with hypertension should not be made when the patient is acutely ill (example – a patient in pain). The reason you take a measurement in each arm is to evaluate whether an adult patient actually has “coarctation of the aorta” or another aortic anomaly, where the pressure will be high in the right arm but low in the left arm.
Screening Healthy Individuals for High Blood Pressure
According to the United States Preventive Services Task Force, high blood pressure screening in health individuals should begin at age 18 and older (USPSTF, 2007). There is insufficient evidence to recommend an optimal interval for screening adults for hypertension. The JNC 7 recommends screening every 2 years in persons with blood pressure less than 120/80 mm Hg and every year with systolic blood pressure of 120 to 139 mm Hg or diastolic blood pressure of 80 to 90 mm Hg. JNC 8 did not comment on screening for hypertension.
Proper Office Blood Pressure Measurement Techniques
|Narrated Slideshow of Proper Office BP Techniques|
One of the most common causes of misdiagnosis or improper management decisions regarding hypertension involves blood pressure measurement errors. These errors are made by staff, nurses, medical students, and physicians alike. Proper office techniques include: 1) having the patient seated quietly for 5 minutes in a chair (not on an exam table), feet on the floor, and arm supported at heart level. 2) using an auscultatory method with a properly calibrated and validated instrument such as an aneroid device which uses a metal spring to measure blood pressure. These have a round compass-like face that is attached to a cuff and accompanied by a stethoscope, and are common in physicians’ offices. 3) using an appropriate-sized cuff should be used to ensure accuracy. The length of the bladder should wrap around 80% of the arm circumference and the width of the cuff must be at least 40% of the arm circumference. If the cuff is too small, the blood pressure reading may be erroneously high. If the cuff is too large, the reading may be slightly too low. With increasing prevalence of obesity today, many adults no longer fit “standard” adult blood pressure cuffs and may require an “extra large” or “thigh” cuff to go around their arms (Jonas et al. JAMA 2003; Graves et al. Blood Pressure Monitoring 2003).
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