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55 Cards in this Set
- Front
- Back
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in which patients does hypertensive crisis most commonly occur?
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pts w/ a know history of HTN, most typically stage II (accelerated HTN)
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what is the definition of hypertensive crisis?
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a critical elevation in BP (SBP >160 and DBP > 100)
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what is the difference between hypertensive urgency and emergency?
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urgency: HTN crisis w/o acute target organ damage
emergency: HTN crisis w/ target organ damage emergency is worse than urgency |
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describe the pathophysiology of htn crisis
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role of mechanical stress on the vessel wall
endothelial damage leads to activation of clotting cascade and release of vasoconstrictive substances activation of RAA system and release of catecholamines pre-existing HTN actually lowers probability of emergency through adaptive mechanisms increased release of cytokines due to mechanical stretching of vessel |
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describe the role of autoregulation in cerebral blood flow
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a protective mechanism by which cerebral blood flow maintains a constant cerebral perfusion over a large range of mean arterial blood pressure. Chronically hypertensive pts have a right shift in the autoregulatory curve, so that cerebral blood flow is not maintained at low MAP values compared to non-hypertensives. hypertensive pts may require a higher MAP to maintain adequate cerebral blood flow.
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describe the types of target end-organ damage and sx of each
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hypertensive encephalopathy: HA, altered level of consciousness, advanced retinopathy with arteriolar changes, hemorrhages and exudates, papilledema seen on examination of fundi
acute aortic dissection: dependent not only on elevation of BP but also on velocity of the left ventricular ejection acute pulmonary edema w/ respiratory failure acute MI/UA eclampsia: visual defects, severe HA, szr, CVA, severe RUQ ab pain, CHF, oliguria ARF: hematuria, proteinuria, increased SCr Microangiopathic hemolytic anemia |
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how is Cerebral perfusion pressure (CPP) calculated?
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CPP = MAP - ICP (intracranial pressure)
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what is perioperative HTN and how is it treated?
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SBP >20% pre-op reading for 15 minutes or >50% increase from original value. incidence is almost 50% depending on the surgery.
etiology: vasoconstriction (catecholamines/baroreceptors) combined w/ intravascular hypovolemia antihypertensive tx reduces myocardial/neurological ischemia, neuro deficits, mortality |
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describe postoperative hypertension
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generally lasts for about 2-6 hrs post surgery
requires rapid control of blood pressure: control bleeding at suture sites, neurology checks, myocardial ischemia develops due to increased oxygen needs higher association w/ ICU admissions and mortality |
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describe pre-eclampsia
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pregnancy related HTN
classified as mild or moderate based on BP, protenuria, platelets, LFTs, clotting studies, bilirubin. HELLP syndrome characterized by hemolysis, elevated liver enzymes, low platelet count -reflect pts w/ greatest risk for morbidity and mortality |
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describe the ideal pharmacologic considerations to treating HTN crisis
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easy transition to PO meds
no increase in ICP absence of coronary/cerebral steal phenomenon minimal ADRs low # of dosage adjustments maintenance of BP control rapid onset of action administration/cost |
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what are the goals of therapy when treating HTN crisis?
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tx the pt, not the BP reading
lower MAP or DBP over an acceptable time frame based on severity of the cirsis and individual pt tolerance w/o provoking cerebral/cardiac hypoperfusion, stroke, or MI hypertensive emergency: decrease MAP by 20-30% over 30-60minutes or decrease DBP by 5-10 mmHg q 5-10 minutes to a DBP of 100 hypertensive urgency: reduce DBP greadually over a period of 12-24 hours HTN emergency requires IV tx HTN urgency may be tx w/ IV or PO therapy |
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what are the five categories of treatment options for HTN crisis?
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BBs
CCBs ACE-Is Nitrovasodilators DA agonists |
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what is the moa of sodium nitroprusside?
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arterial and venous vasodilator which decreases both pre and afterload
nitroprusside is metab by blood vessels to nitric oxide leading to cGMP and vasodilation has little effect on renal blood flow and myocardial O2 demand |
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what is the normal dosing of sodium nitroprusside?
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0.5-1 mcg/kg/min to a max of 10mcg/kg/min
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what are some special considerations w/ regards to sodium nitroprusside?
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unstable under alkaline conditions and light
high dose for 48 hrs (or >4mcg/kg/min for >24h) may result in cyanide and thiocyanate toxicity tolerance doesn't usually develop as it does w/ NTG |
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what is the onset of action of sodium nitroprusside?
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30s - 2min
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what ADRs are associated w/ sodium nitroprusside?
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hypotension w/ rapid infusion rates, thiocyanate and cyanide toxicity
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what it the MOA of labetolol?
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selective a and nonselective B adrenergic recpt blocker w/ a:B ratio of 1:7; alpha blocking is responsible for vasodilation of arterial smooth muscle and B blocking effects the smooth muscle as well as sympathetic stimulation
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cyanide toxicity may result in what?
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cardiac arrest, coma, seizure, enephalopathy
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what is the MOA of nitroglycerin (NTG)?
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potent vasodilator that decreases BP by decreasing preload and cardiac output
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what is the normal dose for NTG?
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5-100 mcg/min, prime tubing
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what is the onset and duration of action for NTG
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onset: 2-5 minutes
duration: 5 minutes |
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what ADRs are associated w/ NTG?
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HA, tachycard, hypotension, tolerance w/ prolonged use; compromised renal/cerebral perfusion due to decreased preload and CO
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what is the normal dose of labetalol?
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20 mg bolus then 0.5 to 2 mg /min w/ max of 5 mg/min
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what is the onset and duration of action for labetalol?
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onset: 5-15min
duration: 2-12 h |
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what are the ADRs associated w/ labetalol?
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heart block, orthostatic hypotension
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what is the moa of esmolol?
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cardioselective beta blocker, decreases sympathetic tone
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what is the normal dosing for esmolol?
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500mcg/kg over 1 min than 50 mcg/kg/min w/ max 300 mcg/kg/min (titrate q 5 min)
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what is the onset of action and duration of esmolol?
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onset: seconds
duration: 10-20 minutes very short duration is desired in ICU; if desired effect is not observed by bolus administration, repeat bolus before infusion rate is increased |
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what ADRs are associated w/ esmolol?
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hypotension, nausea
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in which pts is esmolol useful?
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pts w/ acute MI; also, no dose adjustments for renal/hep failure
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what is the MOA for fenoldopam?
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DA1 agonist: dilation of coronary, renal (afferent/efferent)arteries; appears to be 5-10 times more potent than dopamine for a renal vasodilator
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what is the normal dose for fenoldopam?
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1 mcg/kg/min and increase by 0.05-0.02 mcg/kg/min then taper about 12% q 15-30min
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what are the adrs associated w/ fenoldopam?
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tachycardia, nausea, flushing
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what is the onset of action and duration for fenoldopam?
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onset: 5-15 minutes
duration: 30-60 minutes |
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what is the moa of nicardipine?
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2nd generation DHP CCP, particularly selective for cerebral and coronary vessels; cardiac sparing effects, so no contractility supression
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what is the normal dose for nicardapine?
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5 mg/hr titrated q 5 min by 2.5mg to max of 15 mg/hr. bolus dosing not FDA approved
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what is the onset and duration of action for nicardapine?
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onset: 1-5 min
duration: 2-6 hours |
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what ADRs are associated w/ nicardapine?
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tachycardia, HA
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what is the MOA for hydralazine?
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vasodilator that reduces total peripheral resistance by direct action on vascular smooth muscle; agent has unpredictable effects on BP and is difficult to titrate
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what is the normal dose of hydralazine?
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10-20mg IV q 6-8 hrs, initially slower onset 5-15 minutes, then precipitous fall in BP lasting 12 hours
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what are the ADRs associated w/ hydralazine?
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tachycardia, HA, aggravation of angina
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what is the MOA of enalaprilat?
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reduces serum aldosterone, redution in TPR and afterload (this is the only IV ACE-I)
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what is the normal dose used for enalaprilat?
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0.625 - 5 mg IV q 6 H
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what is the onset and duration of action for enalaprilat?
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onset: 15-30 min
duration: 6 H |
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what are the ADRs associated w/ enalaprilat?
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precipitous fall in BP in high renin states, variable responses
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why is nifedipine NOT used to treat HTN crisis?
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Even with administration via sublingual route the absorption through buccal mucosa is poor
- Sudden uncontrolled reductions in BP have been reported - Nifedipine can precipitate cerebral, renal, and myocardial ischemia FATAL OUTCOMES - FDA recommends that nifedipine NOT be used to treat HTN crises |
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which drug is best for pts w/ severe renal and hepatic insufficiency and MI?
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NTG
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which drug is best for treating eclampsia or pre-eclampsia
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hydralazine
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which drug is best for preoperative pts w/ aortic dissection?
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esmolol
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which drug is best for pts w/ renal insufficiency and risk for cyanide toxicity?
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fenoldopam
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which drug is best for coronary, cerebral or PAD, and surgery pts?
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nicardapine
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which drug is best for pts with HF and risk for cerebral hypotension?
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enalaprilat
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which drugs should be used in pts w/ coronary insufficiency (avoid in HF, COPD, and decreased HR)
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labetalol
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