Treatment of hypotension Flashcards

1
Q

Define blood pressure

A

Blood pressure is the pressure exerted by blood on blood vessels

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2
Q

How can blood pressure be regulated in the short term?

A

Short term regulation:

Baroreceptors
Sympathetic and parasympathetic outflow

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3
Q

How can blood pressure be regulated in the long term?

A

Long term:

Hormonal control of total body sodium:
Control of blood volume, via ECFV
Degree of vasoconstriction

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4
Q

Remind yourself of the BP equation

A

CO = BP/TPR

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5
Q

What are the 3 stages of hypotension?

A

Stage 1 hypertension ≥ 140/90
Stage 2 hypertension ≥ 160/100
Severe hypertension ≥ 180/110

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6
Q

What is hypotension a risk factor for?

A
Hypertension is a risk factor for
Stroke, Ischemic heart disease, 
Left ventricular hypertrophy, Heart failure
Renal failure, 
Retinopathy,
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7
Q

What are the 5 causes of hypotension, both secondary and primary?

A

Secondary (identifiable cause, <10%)
Renal disease
Vascular – e.g., renal artery stenosis
Hormonal – e.g., Conn’s syndrome, Cushing’s syndrome
Monogenic genetic diseases – e.g., Liddle’s
Primary or essential (unknown cause, >90%)
Genetic pre-disposition and environmental factors are proposed to cause essential hypertension through many mechanisms

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8
Q

Why treat hypotension?

What are the goals of antihypertensive treatment?

What are treatment pathways?

A

Risk reduction, e.g., 5 mm Hg drop in diastolic BP for 5 years
Reduce strokes by 42%
Reduce heart attacks by 16%
Reduce vascular mortality by 21%

Goals of anti-hypertensive treatment
Adequate blood pressure control - < 140/90 mmHg, alter relative risk
Prevention of target organ damage
Controlling other cardiovascular risk factors

Treatment pathways
Non-pharmacological: life-style modifications
Pharmacological treatment
Surgical (if known cause, e.g. Conn’s syndrome)

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9
Q

What lifestyles changes can we make to help treat hypotension?

A
Quit smoking
Weight control
Eat less salt
Regular exercise
Reduce alcohol intake
Behavioural therapies, e.g., CBT
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10
Q

What are the major classes of antihypertensive drugs? (5)

A
ACE inhibitors
Angiotensin II receptor blockers
Diuretics
Drugs acting on Sympathetic Nervous System
Vasodilators
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11
Q

How do ACE inhibitors inhibit vasoconstriction and aldosterone secretion?

A

On image

Decrease in vasoconstriction and aldosterone secretion to reduce blood pressure

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12
Q

What are the side effects of ACE inhibitors and ACE in/ Angiotensin 2 receptor blockers

A

Side effects: ACEi:

Cough (common) due to decrease in bradykinin breakdown

Angioedema (rare but serious)

Side effects: both ACEi and ARBs:

Hyperkalaemia

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13
Q

How do diuretics reduce BP?

A

Reduce blood volume → reduces CO → reduce BP (BP ≈ CO x TPR)

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14
Q

How do B1 blockers and alpha-1 treat BP?

A

β1 – increase HR and contractility → increase CO → increase BP
α1 – vasoconstriction → TRP → increase BP

Beta blockers (β1 blockers, e.g. atenolol): reduction in CO and renin release

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15
Q

How do K channel openers cause vasodilation?

A

Arterioles normally have significant smooth muscle tone – scope for relaxation

Increased outward K current
Hyperpolarization
Reduced VGCC activity
Reduced [Ca]i
Less MLCK activity ->  Increased relaxation (vasodilatation)
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16
Q

How does voltage-dependent calcium channel blockers cause vasodilation

A

Arterioles normally have significant smooth muscle tone – scope for relaxation
Block VGCC activity in VSMCs
Reduced [Ca]i
Less MLCK activity -> Increased relaxation (vasodilatation)

17
Q

What are some key issues to consider during drug therapy?

A

Key issues to consider in selecting Drug Therapy:

Essential vs. secondary hypertension
Evidence of efficacy
Side effects of drug
Drug interactions
Individual demographics
Co-existing diseases
Quality of life
Economic considerations
Complicated – so there are guidelines: NICE – National Institute for Health and Clinical Excellence