LEC 9.4: Blood Pressure | Vitals

Blood Pressure

Measure of force of blood against the walls of the arteries as the heart pumps it around the body

Important indicator of heart health

Millimeters of mercury (mmHg)

Units for blood pressure

1. Pumping Action of the Heart

2. Peripheral Vascular Resistance

3. Blood Volume

4. Blood Viscosity

What factors determine arterial blood pressure?

Pumping Action of the Heart

(Factor that determines arterial blood pressure)

• When weak, less blood is pumped into arteries —> Lower Cardiac Output —> BP decreases

• When strong, volume of blood pumped into circulation increases —> Higher Cardiac Output —> BP increases

Peripheral Vascular Resistance

(Factor that determines arterial blood pressure)

• Diastolic pressure especially is affected by this

• Some factors of this include:

  • Capacity of arterioles and capillaries

  • Compliance of arteries

  • Blood viscosity

• If elastic and muscular tissues, arteries lose much of ability and become fibrous tissue —> lose ability to constrict and dilate —> Arterioclerosis

Arteriosclerosis

Condition in which arteries lose much of ability and become fibrous tissue —> lose ability to constrict and dilate

Blood Volume

(Factor that determines arterial blood pressure)

• When this decreases (patient is having hemorrhage or dehydrated) —> BP decreases due to decreased volume in arteries

• When this increases (rapid IV infusion or over infused px) —> BP increases due to greater fluid volume within circulatory system

Blood Viscosity

(Factor that determines arterial blood pressure)

• BP is higher when blood is highly thick —> proportion of RBCs to blood plasma is high

1. Age

2. Exercise

3. Stress

4. Race

5. Sex

6. Medications

7. Obesity

8. Diurnal Variations

9. Medical Conditions

10. Temperature

What are the factors that affect BP?

Age

(Factor that affects BP)

• BP increases as one gets older

Exercise

(Factor that affects BP)

• Physical activity increases the cardiac output —> increased BP

• Need to assess BP after 20-30 mins following an __

Stress

(Factor that affects BP)

• Stimulation of the sympathetic nervous system also increases the CO and vasoconstriction of the arterioles

Race

(Factor that affects BP)

• African-Americans older than 35 years tend to have higher BP than other __ of the same age

Sex

(Factor that affects BP)

• After puberty, females usually have lower BP than males

• After menopause, females usually have higher BP than males

Medications

(Factor that affects BP)

• Caffeine may increase or decrease BP

Diurnal Variations

(Factor that affects BP)

• Usually lowest in the early morning

Temperature

(Factor that affects BP)

• Due to increased metabolic rate, fever can increase BP

Hypertension

Blood pressure that is persistently above normal

Usually asymptomatic and often conrtibuting factor to Myocardial Infarction

Elevated blood pressure that is measured twice at different times

How is hypertension diagnosed?

Primary Hypertension

Elevated blood pressure of unknown cause

Secondary Hypertension

Elevated blood pressure of known cause

Hypotension

BP that is below normal, a systolic reading consistently between 85-110 mmHg in an adult whose normal pressure is higher than this

Orthostatic/Postural Hypotension

BP that decreases when client changes form a supine to sitting or standing position

Falls

If a patient has hypotension, what are they at risk of?

Place client in supine position for at least 5 minutes before we let them stand

What intervention should be done for a patient with orthostatic hypotension to prevent risk of falling?

• Meperidine hydrochloride

• Bleeding

• Severe burns and dehydration

What can cause hypotension?

Systolic: <120 AND

Diastolic: <80

Normal BP

Systolic: 120-129 OR

Diastolic: <80

Elevated BP

Systolic: 130-139 OR

Diastolic: 80-89

Hypertension, Stage 1

Systolic: >140 OR

Diastolic: >90

Hypertension, Stage 2

Bladder

Part of BP cuff that is the bag that can be inflated with air

Sphygmomanometer

Indicates the pressure of the air within the bladder

Sphygmomanometer

What do electronic/digital BP monitoring devices eliminate the use of?

BP erroneously elevated

What occurs if a BP cuff is too narrow?

BP erroneously low

What occurs if a BP cuff is too big?

40% circumference or 20% wider than the midpoint of the limb

What should the width of the BP cuff be?

Direct

Invasive measuring of BP - insertion of catheter into brachial, radial, or femoral artery

Arterial pressure is represented as wave-like forms displayed on a monitored

Indirect

Non-invasive measuring of BP - auscultatory and palpatory methods

Korotkoff Sounds

What do we identify using the stethoscope when measuring BP?

True

True or False: There are 5 phases of Korotkoff sounds but all may not be heard.

First tapping sound is heard (Phase 1)

How do we determine the systolic pressure?

Phase 1

(Korotkoff sound)

Pressure level at which the first faint clear tapping or thumping sounds are heard

Phase 2

(Korotkoff sound)

Muffled, swishing or whooshing sound is heard

Phase 3

(Korotkoff sound)

Blood flows freely through an increasingly opened artery and sounds become crisper and more intense, assume thumping quality but softer than tapping in phase 1

Phase 4

(Korotkoff sound)

Softer blowing muffled sound that fades

Phase 5

(Korotkoff sound)

Pressure level when last sound is heard, followed by period of silence

Pressure at which last sound is heard

How do we determine the diastolic pressure?