Hyper and Hypotension therapies Flashcards
What is the classification of hypertension and how do patients present?
> 140mmHg and/or 90mmHg
Asymptomatic presentation = compliance issues
What is the aim of antihypertensives?
Reduce CO and TPR by targeting the vasculature
What normally controls BP?
Baroreflex, ANS innervation to heart, sympathetic to vessels and RAAS
What determines the choice of antihypertensive?
Age and genetics with gentics influencing most.
What is the antihypertensive drug pathway?
<55yrs —> A —> // >55yrs —> C or D
—> A+C or A+D —> A+C+D —> Diuretics, alpha and beta blockers
What is the mechanism of action of ACEi (A)?
e.g. lisinopril, enalapril
Decrease AngII for reduced vasoconstriction and aldosterone release = Reduce TPR and CO
Decrease degradation of vasodilator kinins = prolong dilation
What are the s.e. of ACEi?
Dry cough as bradykinin enters lungs for bronchodilation and irritates nerve endings.
Sudden hypotension if used with diuretic
How is ACEi used?
First line treatment for mild hypertension in young pts.
What is the mechanism of action of ARBs (A)?
Ang receptor blockers e.g. irbesartans, losartan
Blocks AT1 receptors for vasodilation to reduce TPR and CO
When is ARBs used?
If ACEi cannot be tolerated
What is the mechanism of action of CCB (C)?
e.g. DHP, verapamil
Targets smooth muscle of arterioles to reduce TPR. Has no effect on heart, kidneys or venous vessles.
When are CCB used?
To treat mild hypertension
May affect GIT activity
What is the mechanism of action of diuretics (D)?
e.g. Thiazides = Na/Cl symporter, Furosemide (NKCC loop diuretic).
Work to affect the blood and CO by increasing water and Na excretion to reduce blood volume and CO.
What is the long term effect of diuretics?
Arterial dilation results from the long term low TPR as Na depletion reduces intracellular Ca so smooth muscle cannot contract.
Which are the best diuretics to use?
Thiazides > loop diuretics
What are the side effects of diuretics?
Hypokalaemia due to the reduced Na `
When is a diuretic used?
First line for mild hypertension
How does a beta blocker affect hypertension?
e.g. propanolol, atenolol
Acts on symp NS to reduce HR, contractility, renin and CO.
What are the side effects of beta blockers?
Cause bronchospasm if target beta2 in a pt with asthma
Long term use increases risk of DM
Exercise intolerance as blocking beta1 so no raise in HR
When is a beta blocker used?
Usually avoided unless young female or stable on it
How do alpha blockers affect hypertension?
e.g. prazosin, dozazosin. Works to block constriction in all vasculature to reduce TPR and CO
What are the s.e. of alpha blockers?
Postural hypertension due to inability to constrict lower extremities.
When are alpha blockers used?
Only in severe hypertension that is sudden or unmanagable or for pts with renal/cardiac problems.
How are the antihypertensive drugs grouped?
Target RAAS: A or B
Targer smooth muscle: C or D
Choose one from each group or use all 3 if severe
How is chronic hypertension that continues to get worse treated?
Not with an increase in dose but through combination therapy at low doses to reduce the toxic effects.
What causes hypotension?
Haemorrhage, burns, anaphylatic or hypovolaemic shock.
How is hypotension treated?
Sympathomimetics e.g. Ad to alpha receptors for vasoconstriction or beta receptors for increased HR = increases CO and BP
Can treat by treating the cause e.g. fluids, blood
