Hypertension

Core Concepts

What the two numbers mean

The top number, systolic pressure, is the peak pressure during ventricular contraction (when the heart squeezes). The bottom number, diastolic pressure, is the lowest pressure while the heart relaxes and refills. Both matter: systolic pressure rises with age as arteries stiffen, and in older adults it is often the more important predictor of risk. Classification thresholds for "elevated," "stage 1," and "stage 2" hypertension vary between guideline bodies (for example, commonly cited cutoffs of 130/80 versus 140/90 mm Hg), so nurses should learn the classification used by their institution and current national guidelines rather than memorizing a single number.

The body's pressure-control systems

Pressure is not a passive number — it is actively regulated minute by minute. Baroreceptors in the carotid arteries and aorta sense stretch and trigger rapid adjustments in heart rate and vessel tone. The renin-angiotensin-aldosterone system (RAAS) responds over hours to days: when the kidneys sense low pressure or low sodium delivery, renin starts a cascade that produces angiotensin II (a powerful vasoconstrictor) and aldosterone (which makes the kidneys hold onto sodium and water). The kidneys ultimately set long-term pressure by controlling blood volume. In primary hypertension, these systems become set to a higher level, and the body actively defends the higher pressure — which is why lifestyle and medications must work together to reset it.

How hypertension damages organs

Sustained pressure injures the delicate lining of arteries (the endothelium), making them stiff, thickened, and prone to atherosclerosis. In the heart, the left ventricle must pump against higher resistance and hypertrophies; this increases the risk of heart failure and coronary disease. In the brain, damaged vessels raise the risk of both ischemic stroke and hemorrhage. In the kidneys, narrowed glomerular vessels reduce filtration, and kidney damage in turn worsens hypertension — a vicious cycle. In the eyes, hypertensive retinopathy can be seen on fundoscopy as narrowed, "silver-wired" arterioles, hemorrhages, and exudates. These organ changes are why the same blood pressure number can mean very different things to different people.

Measuring blood pressure correctly

The single most important nursing skill in this topic is measurement technique, because errors change care. The person should be seated quietly for several minutes first, feet flat, with the arm supported at heart level. The cuff must be the right size — a cuff that is too small falsely raises readings, a common error in people with larger arms. The nurse should take more than one reading and consider readings from both arms on the first visit. Because "white coat" anxiety can raise pressure in the office and masked hypertension can hide it, home monitoring is often used to see the true pattern. A single high reading is not a diagnosis of hypertension; diagnosis is based on multiple elevated readings over time.

Hypertensive crisis

When blood pressure climbs very high and is accompanied by acute target-organ damage — such as chest pain, shortness of breath, neurologic changes, or visual disturbance — the situation is a hypertensive emergency requiring urgent treatment. The nurse's job in this situation is rapid, systematic assessment, prompt reporting, and careful monitoring, because the specific drugs and targets are determined by the care team and institutional protocols, not by the bedside nurse. Educational point: it is the presence of organ damage, not the number alone, that defines a crisis.

Primary versus secondary: thinking like a detective

When a younger person, or someone who responded well to treatment before, develops high blood pressure suddenly, the nurse should wonder about secondary causes — kidney disease, renal artery stenosis, endocrine disorders, or medications such as corticosteroids, decongestants, and some oral contraceptives. Asking "when did this start and what changed?" is a nursing assessment that can redirect the whole workup.

Common Confusions