Treatment of hypotension Flashcards
Define blood pressure
Blood pressure is the pressure exerted by blood on blood vessels
How can blood pressure be regulated in the short term?
Short term regulation:
Baroreceptors
Sympathetic and parasympathetic outflow
How can blood pressure be regulated in the long term?
Long term:
Hormonal control of total body sodium:
Control of blood volume, via ECFV
Degree of vasoconstriction
Remind yourself of the BP equation
CO = BP/TPR
What are the 3 stages of hypotension?
Stage 1 hypertension ≥ 140/90
Stage 2 hypertension ≥ 160/100
Severe hypertension ≥ 180/110
What is hypotension a risk factor for?
Hypertension is a risk factor for Stroke, Ischemic heart disease, Left ventricular hypertrophy, Heart failure Renal failure, Retinopathy,
What are the 5 causes of hypotension, both secondary and primary?
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
Why treat hypotension?
What are the goals of antihypertensive treatment?
What are treatment pathways?
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)
What lifestyles changes can we make to help treat hypotension?
Quit smoking Weight control Eat less salt Regular exercise Reduce alcohol intake Behavioural therapies, e.g., CBT
What are the major classes of antihypertensive drugs? (5)
ACE inhibitors Angiotensin II receptor blockers Diuretics Drugs acting on Sympathetic Nervous System Vasodilators
How do ACE inhibitors inhibit vasoconstriction and aldosterone secretion?
On image
Decrease in vasoconstriction and aldosterone secretion to reduce blood pressure
What are the side effects of ACE inhibitors and ACE in/ Angiotensin 2 receptor blockers
Side effects: ACEi:
Cough (common) due to decrease in bradykinin breakdown
Angioedema (rare but serious)
Side effects: both ACEi and ARBs:
Hyperkalaemia
How do diuretics reduce BP?
Reduce blood volume → reduces CO → reduce BP (BP ≈ CO x TPR)
How do B1 blockers and alpha-1 treat BP?
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
How do K channel openers cause vasodilation?
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)
