Blood Pressure Assessment: A Comprehensive Guide

What is Blood Pressure?

Blood pressure (BP) is a vital sign that measures the force of blood pushing against artery walls. It's a key indicator of cardiovascular health and is recorded as two numbers (e.g., 120/80 mmHg):

Systolic: Pressure during heartbeats (ventricular contraction)
Diastolic: Pressure between beats (ventricular relaxation)
Measured in mmHg (millimeters of mercury)

Normal blood pressure is essential for adequate tissue perfusion and organ function.

Blood Pressure Physiology

Blood pressure is determined by several physiological factors:

Cardiac output: Heart rate × stroke volume
Peripheral resistance: Arterial diameter and elasticity
Blood volume: Total circulating blood volume
Blood viscosity: Thickness of the blood
Vessel elasticity: Arterial compliance

Blood Pressure Regulation

The body maintains blood pressure through complex mechanisms:

Short-term: Baroreceptor reflex, chemoreceptors, CNS ischemic response
Medium-term: Renin-angiotensin-aldosterone system (RAAS)
Long-term: Renal fluid balance regulation

Blood Pressure Measurement

Accurate measurement is crucial for proper diagnosis and management:

Preparation

Patient should rest for 5+ minutes
Back supported, feet flat on floor
Arm at heart level (midsternum)
No caffeine, smoking, or exercise 30 mins prior
Empty bladder if needed
No talking during measurement

Cuff Placement

Use appropriate cuff size (bladder encircles ≥80% of arm)
Wrap cuff 1 inch above elbow crease
Centered over brachial artery
Snug but not tight (2 fingers should fit under cuff)
For thigh measurements, use larger cuff

Measurement Technique

Manual: Palpate radial pulse, inflate 30 mmHg above disappearance
Place stethoscope over brachial artery
Deflate at 2-3 mmHg per second
First Korotkoff sound = systolic
Disappearance of sounds = diastolic
Automated: Follow device instructions

Common Measurement Errors

Error	Effect on BP	Solution
Wrong cuff size	Too small: False high Too large: False low	Measure arm circumference
Arm position	Below heart: False high Above heart: False low	Support at heart level
Talking/movement	False high	Ensure patient is still and quiet
Rapid deflation	False low systolic, high diastolic	Deflate 2-3 mmHg per second
White coat effect	False high	Take multiple readings, consider ambulatory monitoring

Blood Pressure Categories (Adults)

According to the American Heart Association 2017 guidelines:

Normal

<120/<80 mmHg

Optimal blood pressure with lowest cardiovascular risk

Elevated

120-129/<80 mmHg

Increased risk of developing hypertension

Stage 1 Hypertension

130-139 or 80-89 mmHg

Lifestyle changes and possibly medication

Stage 2 Hypertension

≥140 or ≥90 mmHg

Requires medication and lifestyle changes

Hypertensive Crisis

>180 and/or >120 mmHg

Immediate medical attention required

Hypertensive Emergency Symptoms

Seek immediate medical care if high BP is accompanied by:

Severe headache
Blurred vision
Chest pain
Shortness of breath
Nausea/vomiting
Severe anxiety
Seizures
Unresponsiveness

Factors Affecting Blood Pressure

Blood pressure fluctuates based on various physiological and environmental factors:

Category	Factors	Effect
Physiological	Age, genetics, circadian rhythm	Long-term BP patterns
Behavioral	Diet (salt, alcohol), exercise, stress	Short-medium term changes
Environmental	Temperature, noise, altitude	Temporary fluctuations
Medical	Medications, kidney disease, hormones	Sustained changes
Measurement	Cuff size, position, technique	Artificial readings

Common Medications Affecting BP

Medication Class	Examples	Effect
NSAIDs	Ibuprofen, naproxen	Increase BP
Decongestants	Pseudoephedrine	Increase BP
Antidepressants	SNRIs, MAOIs	Increase BP
Oral contraceptives	Estrogen-containing	May increase BP
Diuretics	Hydrochlorothiazide	Decrease BP

Special Considerations

Several clinical situations require special attention to blood pressure measurement:

Upper vs. Lower Extremity Differences

Finding	Normal Range	Clinical Significance
Arm-leg systolic difference	10-20 mmHg higher in legs	Normal physiological variation
Lower leg BP	ABI 0.9-1.3	ABI <0.9 = PAD ABI >1.4 = Arterial stiffening
Higher arm BP	Arm-leg difference >20 mmHg	Coarctation of aorta

Pulse Pressure Analysis

Pulse pressure = Systolic BP - Diastolic BP

Normal: 40-60 mmHg
Wide (>60 mmHg): Arterial stiffness, aortic regurgitation, hyperthyroidism
Narrow (<40 mmHg): Heart failure, aortic stenosis, hypovolemia

Isolated Hypertension Types

Type	Definition	Clinical Significance
Isolated systolic hypertension	≥140/<90 mmHg	Common in elderly, arterial stiffness
Isolated diastolic hypertension	<140/≥90 mmHg	More common in younger adults
White coat hypertension	High in clinic, normal outside	15-30% of "hypertensive" patients
Masked hypertension	Normal in clinic, high outside	Higher cardiovascular risk

Related Conditions

Conditions often associated with blood pressure abnormalities: