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NancyPHARM205 > Tut3: Blood Pressure > Flashcards

Tut3: Blood Pressure Flashcards

Only completed up to drugs beta blockers etc

0
Q

What is blood pressure?

A

A measure of pressure of blood against the walls of the arteries

A ration of maximum (systolic) over minimum (diastolic) pressure

Normal blood pressure 120/80

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1
Q

List the functions of the circulatory system

A
  • Obtains O2 from lungs, nutrients from GIT, hormones from endocrine glands and delivers to the tissues that need them
  • moves metabolic waste products CO2, lactic acid, urea from tissues
  • transports antibodies and leukocytes to areas of inflammation
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2
Q

What is mean arterial pressure?

A

Systolic - diastolic gives the pulse pressure,

the heart is in systole 2/3 of the time ?????

MAP= diastolic + 1/3 pulse pressure

MABP = COxTPR

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3
Q

What are the four ways of blood pressure measurement?

A

Invasive- penetrating arterial wall e.g. In ICU

Non-invasive - routine examinations and monitoring

Auscultatory method- using stethoscope and sphygmomanometer

Oscillometric method - using sphygmomanometer cuff with an electronic pressure sensor (transducer), electronics and automatic inflation and deflation of the cuff

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4
Q

What is hypotension?

A

A fall in the blood pressure

May cause insufficient blood flow to brain > dizziness & fainting

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5
Q

What is postural hypotension?

A

Standing from a supine position - may cause falls in elderly as their baroreceptors are not as sensitive as ours

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6
Q

What is Hypertension ?

A

Consistent elevation in blood pressure

> or equal to 140/90mmhg

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7
Q

What can chronic hypertension cause?

A

Changes in Vasculature and in the heart

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8
Q

What are the risks associated with chronic hypertension?

A

Atherosclerosis, aneurysm, stroke, myocardial infarction, heart failure, kidney failure

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9
Q

How do you classify hypertension?

A

Normal S160 or D>100

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10
Q

What is the goal blood pressure for patients with diabetes or chronic kidney disease?

A

<130/80

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11
Q

What are the mechanisms which regulate mean arterial pressure?

A

Autonomic nervous system

Vasoactive substances

Venous return

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12
Q

How does the ANS regulate MAP

A

PNA- innervates heart. Influences HR and CO

SNS- innervates heart, arterioles and veins. Influences CO and TPR

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13
Q

What do baroreceptors do?

A

Monitor Bp in the systemic circulatory system

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14
Q

Where are baroreceptors found.

A

In the arch of aorta

In the carotid sinuses

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15
Q

What are baroreceptors?

A

Stretch receptors which monitor blood pressure at every heart beat

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16
Q

Describe baroreceptors reflex

A

An increase in blood pressure increases the stretch of aorta and carotid Arteries

This stimulates baroreceptors

Baroreceptors increase their firing of impulses per second in afferent nerves to the vasomotor cortex

This causes a change in autonomic nervous system activity to the CV system

SNA is decreased: veins and arterioles will dilate, heart rate decreases, contractility decrease, > decreased VR, decreased CO, decreased TPR > decreased BP to normal

PNA is increased: decreases HR, decreases CO, > decreased BP to normal

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17
Q

What are the two types of vasoactive substances?

A

Vasoconstrictors and vasodilators

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18
Q

Where are some vasoconstrictors?

A 
Adrenaline and noradrenaline
AngiotensinII
Vasopressin (ADH)
Endothelin
Thromboxane A2
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19
Q

What are some vasodilators?

A

Prostacycline
Nitric oxide
Atrial natriuretic peptide

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20
Q

What does angiotensin II do?

A

Causes secretion of aldosterone > enhances Na+ reabsorption, expands plasma volume, increases MAP

It is a vasoconstrictor which increases TPR and MAP

It vasoconstricts in efferent renal arterioles to help maintain perfusion pressure through kidney

Effects beneficial bp or blood volume decrease

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21
Q

What does venous return do.,

A

It helps to regulate CO by way of changes in VR

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23
Q

What is VR influenced by?

A

Blood volume
SNA stimulation of veins
Skeletal muscle activity
Respiratory activity

24
Q

What are antihypertensives?

A

Drugs which reduce blood pressure. They can affect CO, or PR

25
Q

What factors affect the cardiac output?

A

Cardiac: Heart rate, Inotropic state, Neural, Hormonal

Renal fluid volume control:
Renin-Angiogensin, Pressure Natriuresis, Aldosterone, Atrial Natriuetic factor

26
Q

What factors affect Peripheral Resistance?

A

SNA:
Vasoconstrictor (α), Vasodilator (β)

Humoural:
vasodilator, prostaglandins, kinins, vasoconstrictor, angiotensin, catecholamines

27
Q

What drugs act on the Cardiac Output?

A

Beta blokers
Ca2+ channel blockers (non dihydropyridines) - decreases force of contraction of myocardium
Diuretics

28
Q

What are antihypertensives?

A

Drugs which reduce blood pressure. They can affect CO, or PR

29
Q

What factors affect the cardiac output?

A

Cardiac: Heart rate, Inotropic state, Neural, Hormonal

Renal fluid volume control:
Renin-Angiogensin, Pressure Natriuresis, Aldosterone, Atrial Natriuetic factor

30
Q

What factors affect Peripheral Resistance?

A

SNA:
Vasoconstrictor (α), Vasodilator (β)

Humoural:
vasodilator, prostaglandins, kinins, vasoconstrictor, angiotensin, catecholamines

31
Q

What drugs act on the Cardiac Output?

A

Beta blokers
Ca2+ channel blockers
Diuretics

32
Q

What drugs act on the peripheral resistance?

A 
beta blockers
Ca2+ channel blockers (all)
ACEI/AT receptor blockers
Alpha2 blockers
Alpha2 agonists
vasodilators
33
Q

How do beta blockers work?

A

beta blokers = beta-adrenergic receptor antagonists

  • Reduce cardiac contrcaility and CO
  • Inhibit release of renin from the kidney which decreases production of angiotensin II leading to vasodilation and decreased TPR
34
Q

What are some examples of calcium channel blockers and what do they do?

A

Verapamil decreases HR and myocardial contractility which decreases CO, causes some vasodilation

Nifedipine is a potent vasodilator and decreases TPR. It has weaker myocardial effects

Diltiazem has an intermediate moderate effect on heart and smooth muscle

35
Q

What do ACE inhibitors do?

A

Cause vasodilation (Increase TPR) and inhibit aldosterone response to net sodium loss

36
Q

What do Angiogensin Receptor Blockers do?

A

Promote vasodilation
Increase TPR
Increase sodium and water excretion
Which decreases Plasma volume and decreases CO

37
Q

What do alpha blockers do?

A

Alpha blockers = alpha adrenergi receptor antagonits

reduce vascular resistance therefore reducing BP

38
Q

What is hydralazine and what does it do?

A

Hydralazine = vasodilator
Causes direct relaxation of vascular smooth muscle
Causes reflex tachycardia (IncreasedCO)
Sodium retention (Increased plasma volume)

Administer with beta blocker to counteract unwanted compensatory mechanisms of the heart

39
Q

What does methyldopa do?

A

Centrally acting sympatholytic
Exerts its effects at vasomotor centre in brainstem and inhibits sympathetic discharge

Decreases SNA stimulation of the heart, especially vascular smooth muscle results in some decreased CO and marked decrease in TPR

40
Q

What is hypovolaemia?

A

abnormal reduction in fluid
can be due to haemorrhage or dehydration

reduction in circulating blood volume

41
Q

What is Euvolaemia/normovolaemia

A

maldistribution of fluid. Vasoconstriction of certain areas

42
Q

What is hypervolaemia?

A

fluid overload

43
Q

What three situations can cause fluid imbalance?

A

hypovolaemia, euvolaemia, hypervolaemia

44
Q

what is ardiovascular shock?

A

inadequate blood flow throughout the body

results from reduced blood volume (hypovolumic shock)

profound vasodilation (low resistance shock)

acute failure of the heart to pump (Cardiogenic shock)

45
Q

What is haemorrhage?

A

Excessive blood loss.

20% can be lost -no problem

Mean arterial pressure is maintained by baroreceptor reflex

  • Volume is restored within 24 hours
    Arteriolar constriction reduces capillary pressure and fluid moves from tissues -> plasma
    Urine production is suppressed,
    ADH and angiotensin II stimulate thirst
  • > 30-50% requires transfusion within the golden hour otherwise will lead to irreversible shock - multi organ failure
46
Q

What are the first mechanisms to respond following acute change in pressure?

A

Baro receptors and Chemoreceptors followed by CNS isotonic response

Stress relaxation also respond immediately but their actions are slightly slower

47
Q

When do capillaries and fluid shift responses kick in?

A

Within 2 minutes and 8 minutes respectively

48
Q

When does Aldosterone kick in?

A

by 2 hours

49
Q

When does renal blood volume pressure control kick in?

A

by 4 hours

50
Q

List the responses in order of increasing maximum feedback gain at optimal pressure

A 
Capillary
Fluid shift
Stress relaxation
Aldosterone
Chemoreceptors
Baro receptros
CNS Isotonic response
Renal blood volume pressure control
51
Q

What effect does gravity have on the determination of blood pressure?

A

Gravity affects the Hydrostatic pressure

When standing, BP at ankle ~90mmHg higher than that of heart due to weight of column of blood between the two points

Pressure at the head is ~30mmHg less than at the level of heart

For this reason, BP is always measured at the level of the heart

52
Q

what is the primary goal of the circulatory system

A

increase blood flow to the working muscles

53
Q

How does the circulatory system compensate for exercise?

A

By sympathetic stimulation
By increasing MAP and decreasing local vascular resistantce

CO can increase by 4-5fold due to 3-fold increase in HR and 1.5fold increase in SV

54
Q

What is postural hypotension?

A

A decrease in standing blood pressure.

>10mmHg decrease when associated with dizziness/fainting

55
Q

In which patients is postural hypotension more likely to occur?

A 
Patients with 
Systolic HT (elevated BP)
Diabetes
Taking diuretics/venodilators
Taking psychotropic trugs like PKD
56
Q

What can be done to reduce postural hypotension?

A

Caution to avoid volume depletion and excessively rapid dose titration of antihypertensive drugs

Advise to take time and care when rising from lying/sitting position

57
Q

How is the circulatory system affected in regards to the electrical activity of the heart?

A
  • alteration in rate or rhythm of heart will affect how effectively the heart can pump
  • e.g. in atrial fibrillation there is a lack of meaningful atrial contraction which decreases ventricular filling pressures which in turn decreases CO by about 10-20%
  • MABP = CO x TPR
  • Decreased CO will decrease MAP

NancyPHARM205 (15 decks)

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