Blood Pressure — Overview

What Is Blood Pressure?

Blood pressure (BP) is the force exerted by circulating blood against arterial walls. It is expressed as systolic / diastolic (mmHg) and determined by two physiologic factors: cardiac output (CO) and peripheral vascular resistance (PVR). Mean arterial pressure (MAP) = ⅓ systolic + ⅔ diastolic; a MAP > 60 mmHg is required to perfuse vital organs.

ACC/AHA BP Classification (Adults)

Category	Systolic	Diastolic	Action
Normal	< 120 mmHg	< 80 mmHg	Healthy lifestyle maintenance
Elevated	120–129 mmHg	< 80 mmHg	Lifestyle modification
Stage 1 HTN	130–139 mmHg	80–89 mmHg	Lifestyle ± pharmacotherapy (based on CVD risk)
Stage 2 HTN	≥ 140 mmHg	≥ 90 mmHg	Lifestyle + pharmacotherapy
Hypertensive Crisis	≥ 180 / ≥ 120 mmHg		Urgent/emergent provider evaluation

Pharmacotherapy

First-Line Antihypertensive Classes

Class	Examples	Key Nursing Note
ACE Inhibitors	Lisinopril	Monitor for dry cough, hyperkalemia, angioedema; hold in pregnancy
ARBs	Losartan, Valsartan	Similar to ACEi but no cough; still contraindicated in pregnancy
Calcium Channel Blockers	Amlodipine, Nifedipine	Monitor for peripheral edema, reflex tachycardia (dihydropyridines)
Thiazide Diuretics	Hydrochlorothiazide	Monitor K⁺, Na⁺, uric acid; avoid in gout; morning dosing preferred
Beta-Blockers	Atenolol, Carvedilol	Do not abruptly discontinue; monitor HR and glucose masking in diabetics
Loop Diuretics	Furosemide	Primarily for Heart Failure-related hypertension; monitor electrolytes closely
Other	Hydralazine, Clonidine	Second/third line; clonidine rebound hypertension on abrupt stop

Nursing Safety

Hypertensive Crisis (≥ 180/120 mmHg)

Hypertensive urgency — severely elevated BP without end-organ damage: oral agents, gradual reduction over 24–48 h. Hypertensive emergency — severely elevated BP with end-organ damage (AKI, stroke, MI, aortic dissection, pulmonary edema): IV agents, MAP reduction ≤ 25% in first hour, then gradual. Notify provider immediately; do not lower too fast — precipitous drops cause ischemia.

Orthostatic Hypotension

Drop ≥ 20 mmHg systolic or ≥ 10 mmHg diastolic within 3 minutes of standing. High risk in elderly, patients on multiple antihypertensives, or those with volume depletion. Instruct patients to rise slowly; assess lying, sitting, and standing BPs. Falls risk — especially in Geriatric Syndromes.

Concept Map

Blood Pressure — Concept Overview

mindmap
  root((Blood Pressure))
    Determinants
      Cardiac Output
        Heart Rate
        Stroke Volume
      Peripheral Vascular Resistance
        Arteriole tone
        Blood viscosity
    Classification
      Normal under 120/80
      Elevated 120-129
      Stage 1 HTN 130-139/80-89
      Stage 2 HTN ≥140/90
      Hypertensive Crisis ≥180/120
    Pharmacotherapy
      ACE Inhibitors
        Lisinopril
      ARBs
        Losartan
        Valsartan
      Calcium Channel Blockers
        Amlodipine
        Nifedipine
      Thiazide Diuretics
        Hydrochlorothiazide
      Beta-Blockers
        Atenolol
        Carvedilol
      Other
        Hydralazine
        Clonidine
    Nursing Monitoring
      BP measurement technique
      Orthostatic hypotension checks
      Electrolyte monitoring
      Fall prevention

Reflection

Blood pressure management is deceptively broad — the pharmacology alone spans five major drug classes with very different mechanisms and monitoring priorities. The clinical skill is matching the drug class to the patient's full picture: an ACE inhibitor is ideal for a diabetic with proteinuria; a beta-blocker is the right add-on for a patient with Heart Failure; a thiazide is first-line in uncomplicated hypertension. As a nurse, I need to know not just what the medication does, but what to watch for after giving it — and when to hold it.

Related Concepts

Hypertension Renin-Angiotensin-Aldosterone System Cardiac Output Orthostatic Hypotension Hypertensive Crisis Heart Failure Geriatric Syndromes