Hypertension Blog

You can derive two measurements from a patient’s systolic and diastolic blood pressures. These measurements can help in detecting conditions related to a patient’s high blood pressure and in understanding the hemodynamic factors that affect blood pressure. One such measurement, pulse pressure, is the difference between the systolic and diastolic pressures. For instance, if a patient’s blood pressure is 120/80 mm Hg, his pulse pressure is 40 mm Hg. Normally, a patient’s pulse pressure is 30 to 40 mm Hg.

Pulse pressure reflects stroke volume (SV), ejection velocity, systemic vascular resistance, and CO. An increased or widened pulse pressure, such as in a patient with a blood pressure of 160/40 mm Hg, signifies increased SV, which could result from the following conditions:

• high blood pressure
• sinus bradycardia
• complete heart block
• aortic regurgitation
• anxiety
• exercise
• catecholamine production
• arteriosclerosis of the large arteries and aorta.

Increases in pulse pressure reduce a patient’s systemic vascular resistance and may appear when a patient has a fever, is in a hot environment, or has been exercising.

A decreased pulse pressure can be caused by factors such as:

• heart failure, which causes reduced ejection velocity
• hypovolemia
• shock.

A patient’s MAP is the average pressure in the arteries throughout the cardiac cycle as influenced by CO and vascular resistance. This pressure varies in different parts of the body, from about 100 mm Hg in the aorta and large arteries to about 0 mm Hg at the end of the vena caval system.

To calculate a patient’s MAP, use the following formula:

MAP = diastolic pressure + Y3 pulse pressure Using this equation, a patient whose blood pressure is 120/80 mm Hg and pulse pressure is 40 mm Hg would have a MAP of 93.2 mm Hg.

Normally, a patient’s MAP ranges from 70 to 100 mm Hg. An increased MAP occurs with primary hypertension, arterial disease, and epinephrine release, and a decreased MAP can indicate decreased vascular resistance, cardiac failure, or hypovolemia.

The current system for classifying blood pressure in people over age 18 defines normal and high normal blood pressure and four categories of increasingly severe hypertension . A patient who has a reading of 130/85 mm Hg or less and who doesn’t take antihypertensive drugs has normal blood pressure. However, a patient in this category still has some cardiovascular risk unless his blood pressure is less than 120/80 mm Hg. If a patient has unusually low readings, he should be evaluated further.

A patient in the high normal category has a systolic reading between 130 and 139 mm Hg and a diastolic reading between 85 and 89 mm Hg. A patient in this category has an increased risk of developing hypertension and should frequently have his blood pressure monitored. He should also be counseled on lifestyle changes that can reduce his blood pressure.

The four stages of hypertension indicate a patient’s increased risk of developing hypertension ­related complications or diseases such as a cerebrovascular accident (CVA), cardiovascular disease, and renal disease.

All stages of hypertension require treatment, though the specific treatment will vary. If left untreated, hypertension results in damage to organs such as the brain, heart, and kidneys. When noting the stage of a patient’s hypertension, you should also identify any organ disease and additional risk factors. For example, a patient with a blood pressure of 142/94 mm Hg and left ventricular hypertrophy plus diabetes should be classified as having stage 1 hypertension with organ disease (left ventricular hypertrophy) and a major risk factor (diabetes).

If a patient’s systolic and diastolic blood pressures fall into two different categories, he should be classified based on the more severe pressure reading. For example, 160/92 mm Hg should be classified as stage 2 hypertension based on the systolic pressure reading. However, a reading of 205/125 mm Hg should be classified as stage 4 hypertension based on the diastolic reading.

Stages 1 and 2 hypertension

Patients with stage 1 (mild) hypertension have systolic blood pressure readings of 140 to 159 mm Hg and diastolic blood pressure readings of 90 to 99 mm Hg. Stage 2 (moderate) hypertensive patients have systolic blood pressure readings between 160 and 179 mm Hg and diastolic readings between 100 and 109 mm Hg. Of the four stages of hypertension, stage 1 is the most common in adults.

The typical treatment of stages 1 and 2 hypertension involves lifestyle modification and, initially, a single antihypertensive drug, such as a diuretic or a beta-blocker. Some physicians may with­hold drugs from patients with diastolic pressures in the 90 to 94 mm Hg range. However, such patients should be examined in 3 to 6 months to determine if their blood pressure has risen or if they’ve experienced cardiac and vascular changes.

Stages 3 and 4 hypertension

A patient with stage 3 (severe) hypertension has a systolic blood pressure reading between 180 and 209 mm Hg and a diastolic blood pressure reading between 110 and 119 mm Hg. And the patient with stage 4 (very severe) hypertension has a systolic blood pressure reading of 210 mm Hg or more and a diastolic reading of 120 mm Hg or more.

Treatment of stages 3 and 4 hypertension also includes lifestyle modification. However, the patient may also need a second or third antihypertensive drug .

Usually, the early grades of hypertensive retinopathy go undetected. A patient may have no significant signs or symptoms to report nor any apparent reason to seek medical attention.

However, as his diastolic blood pressure remains elevated in grades III and IV, retinal lesions may produce blurred vision and scotomata (blind gaps in his visual field). Papilledema or hemorrhage in the macula can result in blindness.

Diagnostic Tests

A physician uses an ophthalmoscopic examination to diagnose hypertensive retinopathy. This examination is used to detect constricted retinal vessels in grades I and II retinopathy and to detect hemorrhages, yellow exudates, and papilledema in grades III and IV retinopathy.

If the patient has papilledema, the ophthalmo­scopic examination will reveal engorged, tortuous retinal veins, flame-shaped retinal hemorrhages in the superficial nerve fiber layer, and round hemorrhages in the deeper nerve layers.