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Systolic Pressure
Peak pressure exerted against arterial walls as the ventricles contract and eject blood
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Diastolic Pressure
Minimum pressure exerted against arterial walls, between cardiac contractions when the heart is at rest
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mm Hg
Measurement for blood pressure
Millimeters of mercury
Is measured as. Systolic over Diastolic
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Pulse pressure
- Due to difference of systolic and diastolic pressure (120/80 -> 40 mm Hg pulse pressure)
- Indication of the volume output of the left ventricle
- Should be no greater than 1/3 of the systolic pressure
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Normal BP for adults
Follow up action
- Current: <120 systolic and <80 diastolic =normal
- Encourage life style modification if risk factors present
- Recheck in 1-2 years, with risk factors sooner
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Prehypertension
Follow up
- 120-139 systolic and 80-89 systolic
- Encourage life style changes
- Recheck in 1year or sooner,
Antihypertensive are prescribed only with compelling (zwingende) indications, such as renal disease
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Stage 1 Hypertension
Follow up
- 140-159 systolic and 90-99 diastolic
- Encourage lifestyle modification,
- Follow up with primary care provider in 1-2 months
- Most patients will be started on thiazide-type diuretics
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Stage 2 Hypertension
- >= 160 systolic and >= 100 diastolic
- Encourage lifestyle modification
- refer for care within 1 week or immediately if warranted
- Most patients will be given a 2-drug combination therapy, e.g. thiazide-type diuretics and angiotensin converting enzyme (ACE) inhibitors
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Which factors influence blood pressure
1,2,3
Cardiac function
Peripheral vascular resistance
Blood volume
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How does cardiac function influence blood pressure?
- increase in cardiac output causes and increase in blood pressure
- A decrease in cardiac output decreases BP
- A change in either stroke volume or heart rate alters cardiac output
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What are factors that increase cardiac output by increasing stroke volume?
Increased blood volume (e.g. pregnancy)
More forceful contraction of the ventricles (e.g. exercise)
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Factors that decrease cardiac output by decreasing stroke volume
- dehydration
- Active bleeding
- Damage to the heart (e.g. myocardial infarct/ heart attack)
- Very rapid heart rate ( not enough time to refill the ventricles)
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Peripheral resistance
Arterial and capillary resistance to blood flow as a result of friction between blood and the vessel walls
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Which factors influence peripheral resistance?
- Viscosity (thickness) of the blood
- Arterial size
- arterial elasticity/compliance
The walls themselves influence very little, as they are very this and distensible (dehnbar)
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What influences Blood viscosity
- hematocrit =percentage of red blood cells in plasma
- Disorder dehydration -> hematocrit increase-> blood. Viscosity increase-> increase blood pressure
- Conversely, low hematocrit e.g. anemia
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What influences arterial size?
- Constricted arteries prevent the free flow of blood -> increase BP
- Dilated arteries allow free blood flow-> decrease in BP
- The sympathetic nervous system regulates vasoconstriction and vasodilation
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How does Arterial compliance influence BP
- Arteries with good elasticity can extend and recoil easily and adequately
- Age or disease related changes may cause a loss of elasticity-> peripheral resistance-> possibly BP (e.g. Arteriosclerosis (hardening of arteries) often cause an increase of BP in middle aged and older adults)
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What is the normal blood volume?
How can blood volume change and how does this influence the BP?
- Normal blood volume is 5 liters = 5000 mL
- Volume decrease e.g. blood loss (hemorrhage) or. Other fluid losses-> decrease vascular (gefaess) volume-> BP falls
- Volume increase e.g. renal (kidney) disease/failure and fluid retention-> BP increases
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Which normal factors influence BP ?
13
- 1 developmental stage 2 family history
- 3 lifestyle 4 exercise 5 body position 6 stress
- 7 pain 8 race 9 obesity 10 diurnal variations
- 11 medications 12 diseases 13 sex
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Sex influence on BP
- The average BP for men is slightly higher than that for women of comparable age
- After menopause women's BP increases
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Developmental stage influences BP
- Average newborn has an average BP of 80/40 mm Hg
- It increases gradually throughout childhood
- Smaller child/adolescent has lower BP
- Than a larger one
- Systolic and diastolic BP increase with age
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Family history influences BP
A family history of hypertension markedly increases the likelihood of an individual developing hypertension
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Lifestyle influences BP
- Increased sodium consumption
- smoking
- 3 or more alcoholic beverages per day
- -> elevate BP
- Caffeine increases BP for. Short time but no long-term effect
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Exercise influences blood pressure
Physical fitness reduces BP in many individuals
Muscular exertion temporarily increases BP as a result of increased heart rate and cardiac output -> wait about 30 minutes before assessing BP of somebody after exercising
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Body position influences BP
- The BP is higher if somebody is standing, than when sitting down or lying down.
- Readings are higher when arm above heart level
- reading higher when arm unsupported
- Reading higher when feet are dangling
- Reading higher when legs are crossed
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Stress influences BP
- Fear, worry, excitement and other stressing factors cause the BP to rise sharply (sympathetic nervous system response -> fight or flight)
- Here also white coat hypertension -> but this shows also effect of other stress types
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Pain influences blood pressure
Pain often causes an increase in BP
Severe or prolonged pain can also cause a dicrease in
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Race can influence BP
Blacks have a higher rate of hypertension than European Americans and they have a higher incidence of complications and hypertension related deaths
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Obesity can influence BP
It increases BP, related to the additional vascular supply required to perfuse the large body mass -> increase in peripheral resistance
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Diurnal variations can influence BP
BP varies according to the person's daily schedules and routines. Usually it is lowest after waking up in the morning
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Medications can influence BP
- Many medications alter BP
- Effect may be intended (antihypertensive meds) or unintended (e.g. drop of BP after pain meds)
- Many over the counter meds and herbs and illicit (illegal) drugs affect BP (cocaine raises BP significantly)
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Diseases can effect BP
Diseases that affect the circulatory system or any of the major organs of the body (e.g. kidneys) may affect the BP
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How can BP be assessed?
Direct and indirect
Direct: catheter treated into artery attached to electronic monitoring system (constant display)
Indirect/noninvasive method: accurate estimate with stethoscope, blood pressure cuff and sphygmomanometer
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sphygmomanometers
aneroid
mercury
electronic
Android : dials that register BP by pointers attached to a spring (frequent calibration)
Mercury: measure BP using a calibrated upright tube containing mercury (health hazard, but easier to maintain)
Electronic use microphones or sensors that detect pressure waves, can be set to monitor and record BP at timed intervals. Can be less accurate, test baseline BP before using electronic)
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Benefits of self monitoring of BP
- May detect high BP
- Allows for observation of BP pattern
- Distinguishes "white coat hypertension"
- Self-monitoring can increase participation in treatment, may improve compliance with treatment
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Disadvantages of self-monitoring of BP
- Possible incorrect use of device
- Needless anxiety over a single high reading
- patient may make adjustment on medication based on the BP readings without asking their doctor
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Nursing implication regarding self-monitoring of BP
- Teach proper use of device
- Periodically check patient's technique
- Teach meaning of BP, patterns, single reading anxiety,
- Explain need for calibration (once a year)
- Teach about abnormal high and low readings
- Advice regarding written record
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What cuff size should I use?
Width of bladder: should cover approx.
2/3 of the upper arm (or other extremity) for an adult
Entire arm for a child
Or cuff width is 40% of the arm circumference and the length of the bladder encircles 80% of the arm in adults
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Incorrect reading when cuff is
too narrow
too wide
too narrow -> too high
Too wide -> too low
Error can be as much as 30 mm Hg, it is better to use a cuff that is too large than one that is too small ( document cuff size if improper size)
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Which side should I use to measure the BP ?
- Usually the brachial artery, not if
- -intravenous access device
- - renal dialysis fistula
- -skin graft
- -paralyzed
- -diseased
- -extensive trauma
- -cast or dressings
- -not on same side of breast or shoulder surgery
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What sounds do you hear by auscultating the BP ?
- Korotkoff sounds
- First systole, last diastole
- 1st hear a sound that occurs during systole,
- 2nd soft swishing sound (blood turbulence)
- 3rd begins midway through BP, sharp, rhythmic tapping sound
- 4th like 3rd, but softer and fading
- 5th silence, it corresponds with diastole
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Palpating blood pressure
- If BP is difficult to hear (cardiac conditions, shock, other conditions) use pulsation alone.
- When deflating the cuff remember systole rate when pulse can be felt , no record of diastole (e.g. Pleated low Fowler's left arm 86/_ or 86 systolic)
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auscultatory Gap
- If patient has hypertension
- -may hear loss of sound for as much as 30mm Hg, followed by return of sound (isolated first sound do not miss when plating correctly) record range of pressure when gap occurs
- (e.g. BP left arm, sitting, 170/90 with an auscultatory gap from 170-140)
Failure to notice the gap can result in serious misreading of the systolic BP
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Hypotension
- Systolic < 100 mm Hg
- Usually no problem, further evaluation if
Dizziness, fatigue, concentration problem, activity intolerance, shortness of breath
- Or
- The low BP is of sudden onset
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Orthostatic/postural hypotension
Sudden drop in BP when moving from a lying position into a sitting or standing position
- -decrease of 10 mm Hg in standing BP
- -together with dizziness/ fainting
- Cause: vasodilator without increase of cardiac output
- ! risk to fall related to dizziness or fainting
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Hypertension
- Persistently higher than normal BP
- > 140 mm Hg or > 90 mm Hg diastolic on two or more separate occasions
- Caused by thickening of the arterial walls and decreased elasticity of the arteries
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Why is hypertension dangerous ?
- Increases stress on heart and blood vessels
- May lead to
- Heart attack,
- Heart failure
- Peripheral vascular disease
- Kidney damage
- stroke
- The higher the BP the more dangerous the situation
- Often delayed diagnosis, as symptoms are mild or absent
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Possible symptoms of hypertension
- Early morning suboccipital headaches
- fatigue
- Visual changes
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Primary/essential hypertension
- Diagnosed if there is no known cause
- At least. 90% of all cases of hypertension
- Although no single cause is identified it can be race, family history,... could contribute
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Secondary hypertension
- Clearly identified cause for hypertension like
- Renal or endocrine disorders
- Drugs (cocaine, amphetamine,)
- Medications nonsteroidal anti-inflammatory drugs (NSAIDs)
- Chronic overuse of alcohol
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