hypertensive emergencies Flashcards
presentation of pts with hypertensive emergency
- headache
- visual changes
- altered level of consciousness
- heart failure
what my happen if BP reduction is too rapid
ischemia in brain or retina leading to stroke or blindness
what are examples of different types of hypertension emergencies
- hypertensive encephalopathy
- hypertensive intercranial haemorrhage
- myocardial ischemia with HTN
- preeclampsia and eclampsia
how do alpha2 receptors in the CNS work
- autoinhibitory receptors
- stop sympathetic outflow from CNS presynaptically
- controlling the release of noradrenaline
- affecting heart, blood vessels and kidney - decrease BP
where do beta blockers work
- B1 act on the heart
- non-selective beta blocker
- can act on lungs causing bronchoconstriction
where do alpha1 receptors act on
- in the blood vessels
- cause vasoconstriction
- blocked causes vasodilation
what are 2 examples of b-blocker medication for HTN
- esmolol
- labetalol
how does esmolol work
- B1 blocked
- decreases heart rate
- decreases force of contraction
- altering cardiac output
how does labetalol work
- alpha1-blocker
- decreases vasoconstriction
- reducing peripheral resistance
- B blocker
- decreasing heart rate and force of contraction
what is calcium channel blocker mechanism of action
- affect calcium channels in blood vessels (smooth muscle cells)
1. block Ca influx
2. lack of Ca in cell = no contraction
3. vasodilated > drops PVR > drops BP
what is an example of Ca channel blockers for HTN
nicardipine
what adverse effects do ca-channel blockers have
- oedema
- headaches
- flushing
- reflex tachycardia
why do ca-channel blockers cause headaches
vasodilation in the cranial nerves
why do ca-channel blockers cause reflex tachycardia
baroreceptor reflex on the heart
mechanism of action of loop diuretics in HTN
inhibit Na/K/Cl uptake in thick ascending limb in loop of Henley = more water in urine
what are the adverse effects of loop diuretics
- ototoxicity
- hyperuricemia
- hypokalaemia
- hypomagnesemia
how does Na nitroprusside work
causes direct vasodilation of arteries and veins
what are the adverse affects of Na nitroprusside
- reflex tachycardia
- headache
- cyanide or thiocyanate toxicity
what medication can be used as management for HTN with preeclampsia and eclampsia
- magnesium sulfate
- hydralazine
- labetalol
- Na nitroprusside
how does magnesium sulfate work in HTN with pre-eclampsia and eclampsia
- vasodilates cerebellar and releax muscles
- blockers peripheral neuromuscular transmission
what is the mechanism of action of hydralazine in pre-eclampsia and eclampsia
directly dilates the peripheral arteries
what are the adverse effects of hydalazine
- relfex tachycardia
- headaches
- flushing
- hypotension
- peripheral oedema
what is the mechanism of action of benzodiazepines with HTN in seizures
- enhances GABA effects
- net result of inhibitory post synaptic potential
- chloride influx = hyperpolarisation inhibiting GABA
- brain depresses CNS, RR and consiousness
what are the adverse effects of benzodiazepines
- respiratory depression
- drowsiness
- headache
- nausea
- oversedation
