Blood Pressure Assessment and Management: A Nursing Fundamentals Guide

Blood pressure (BP) assessment is a core nursing skill tested heavily on fundamentals exams. This note reviews BP definitions, normal and abnormal ranges, proper measurement technique, Korotkoff sounds, orthostatic hypotension, and the major drug classes used to treat hypertension.

Definitions

• Blood pressure (BP) is the force of blood against arterial walls.
• Systolic pressure reflects ventricular contraction.
• Diastolic pressure reflects ventricular relaxation.
• Pulse pressure is the difference between systolic and diastolic pressure. Normal range is 30–50 mmHg.

Blood Pressure Classification (ACC/AHA)

• Hypertensive crisis requires immediate medical attention. Ask the patient about chest pain, shortness of breath, or severe headache.
• Hypotension is clinically significant if the patient has dizziness, confusion, or syncope. Asymptomatic low BP may be normal for some patients.

Proper Measurement Technique

Patient Preparation

• The patient should sit quietly for 5 minutes before measurement.
• Feet flat on the floor, back supported, and arm supported at heart level.
• Do not take BP immediately after exercise, smoking, caffeine, or with a full bladder — these falsely elevate readings.

Cuff Selection

• The cuff bladder should encircle 80% of the arm circumference.
• Cuff too small → falsely high reading
• Cuff too large → falsely low reading
• Correctly sized cuff → accurate measurement

Arm Selection

• Take BP in both arms on the first assessment, then use the arm with the higher reading for subsequent measurements.
• A difference >10 mmHg between arms suggests subclavian artery stenosis or aortic dissection.
• Do not take BP on an arm with an IV infusion, arteriovenous fistula, mastectomy, or injury.

Korotkoff Sounds

• Phase 1 (Systolic): first appearance of repetitive tapping sounds.
• Phase 5 (Diastolic in adults): disappearance of all sounds.
• Auscultatory gap: a silent period between Phase 1 and Phase 2 where sounds disappear then reappear. Can cause falsely low systolic or falsely high diastolic readings.
• To detect an auscultatory gap: palpate the radial pulse while inflating the cuff past the estimated systolic pressure, then deflate slowly while listening.

Common Measurement Errors

• Deflate the cuff at 2–3 mmHg per second. Deflating too quickly causes you to miss the correct reading.

Orthostatic Hypotension

• Orthostatic hypotension: a drop of ≥20 mmHg systolic or ≥10 mmHg diastolic within 3 minutes of standing.
• Causes: dehydration, bleeding, medications (beta-blockers, diuretics), and autonomic dysfunction.
• Measurement sequence: measure BP and pulse after lying down for 5 minutes, then after sitting for 1–2 minutes, then after standing for 1–2 minutes.
• Patients with orthostatic hypotension are at high fall risk — assist with position changes.

Hypertension

• Primary (essential) hypertension has no identifiable cause and accounts for 90–95% of cases. Risk factors: age, obesity, smoking, high sodium intake, sedentary lifestyle.
• Secondary hypertension is caused by an underlying condition such as renal artery stenosis or hyperaldosteronism.
• Complications: heart failure, myocardial infarction, stroke, kidney disease, retinopathy.
• Lifestyle modifications: low-sodium DASH diet, exercise, weight loss, smoking cessation, limited alcohol.

Antihypertensive Medications

Hypotension and Shock

• Common causes of hypotension: dehydration, bleeding, sepsis, heart failure, medication side effects.
• Shock is life-threatening hypotension with inadequate tissue perfusion. Types: hypovolemic, cardiogenic, distributive.
• For a hypotensive patient: assess ABCs first, start IV fluids as ordered, and prepare for vasopressors if needed.
• Raise the patient's legs (Trendelenburg position) to improve venous return while waiting for interventions.

Common Exam Traps

• Do not use a cuff that is too small — it produces a falsely high reading.
• Do not take BP on an arm with an IV or arteriovenous fistula.
• Do not deflate the cuff too quickly — you will miss the correct reading.
• Do not ignore an auscultatory gap — it can cause falsely low systolic or falsely high diastolic readings.
• Do not assume a single high reading is hypertension — confirm with repeat measurements.
• Do not hold antihypertensives for a single low reading without checking the patient's symptoms.
• Do not stop clonidine abruptly — this causes rebound hypertension.
• Do not give the first dose of an alpha-1 blocker in the morning — give at bedtime to prevent falls.

Key takeaways

• Normal BP is <120/80; Stage 1 HTN is 130–139/80–89; hypotension is <90/60.
• Use a correctly sized cuff: too small → falsely high, too large → falsely low.
• Korotkoff Phase 1 = systolic; Phase 5 (disappearance) = diastolic in adults. Watch for the auscultatory gap.
• Orthostatic hypotension = drop of ≥20 mmHg systolic or ≥10 mmHg diastolic on standing; increases fall risk.
• ACE inhibitors → dry cough; hold beta-blockers if HR <60; never stop clonidine abruptly; give alpha-1 blockers at bedtime.