END-ORGAN DAMAGE OF HYPERTENSION Flashcards
Hypertensive Urgencies and Emergencies
Management:
General recommendations:
Gradual BP reduction is generally recommended:
MAP reduction by ~10% to 20% in first hour, then by
An additional 5% to 15% over the next 23 hours, with
Total 24 hour BP reduction < 25%
Hypertensive Urgencies and Emergencies
Exceptions to gradual BP reduction over the first day:
Acute phase of ischemic stroke: BP not lowered unless >185/110 mm Hg in candidates for reperfusion therapy or >220/120 mm Hg for non-candidates.
Acute aortic dissection: SBP should be lowered to target of 100 to 120 mm Hg within 20 minutes and heart rate reduced to <60 beats per minute.
Hypertensive Urgencies and Emergencies
Keep patient euvolemic to reduce further activation of the renin–angiotensin–aldosterone system, with caution not to worsen HTN with excess sodium load.
Head trauma
Treat if cerebral perfusion pressure (mean arterial pressure minus intracranial pressure [ICP]) is >120 mm Hg and ICP is >20 mm Hg.
Acute heart failure
Consider use of intravenous vasodilator such as sodium nitroprusside, nitroglycerin to reduce afterload.
Avoid hydralazine (can increase cardiac work) or β-blockers, for example, labetalol (can decrease cardiac contractility).
Acute coronary syndrome
Consider use of IV nitroglycerin, clevidipine, nicardipine, or esmolol to reduce myocardial oxygen consumption/ischemia.
Acute hypertensive nephrosclerosis, renal emergencies
Clinical manifestations: new-onset microscopic hematuria, elevated creatinine
Acute hypertensive nephrosclerosis, renal emergencies
Renal histopathology: Fibrinoid necrosis of small arterioles (pink, amorphous fibrinoid materials within vessel wall due to necrosis) and “onion skinning” of small renal arteries.
Acute hypertensive nephrosclerosis, renal emergencies
“Onion skinning” is used to describe hyperplastic arteriosclerosis with thickened concentric smooth muscle cell layer with thickened, duplicated basement membrane and narrowed lumen. In malignant HTN, these hyperplastic changes may be accompanied by fibrinoid necrosis of the arterial intima and media.
Acute hypertensive nephrosclerosis, renal emergencies
Renal ischemia activates the renin–angiotensin -aldosterone system (RAAS), thus excerbates the underlying HTN.
Acute hypertensive nephrosclerosis, renal emergencies
BP lowering may lead to worsening kidney function, particularly CCB due to the potential vasodilating effect on afferent arterioles leading to transmission of systemic HTN into glomeruli.
Acute hypertensive nephrosclerosis, renal emergencies
Fenoldopam is associated with a temporary improvement in renal function and may be useful in renal hypertensive emergencies.
Ingestion of sympathomimetic agents (e.g., ingestion of tyramine-containing foods in patients on chronic monoamine oxidase inhibitors, cocaine, amphetamine) or severe autonomic dysfunction (e.g., Guillain–Barré, Shy–Drager syndromes), acute spinal cord injury.
Treat with IV phentolamine or nitroprusside.
Use of β-blockers is contraindicated due to unopposed α-adrenergic vasoconstriction. NOTE: nonselective β-blockers such as labetalol and carvedilol still have predominant β-blocking activity with β-to-α blocking ratio of 7:1 or greater.
Antihypertensive Medications Used in Hypertensive Emergencies
Nitrates: nitroglycerin, nitroprusside:
NO induces arteriolar and venous vasodilatation by activation of calcium sensitive potassium channels (via cGMP) in cell membranes.
Antihypertensive Medications Used in Hypertensive Emergencies
Nitroglycerin
Nitroglycerin:
Low antihypertensive effect
Consider in patients with symptomatic coronary disease or following coronary bypass.
Limitations: methemoglobinemia possible with prolonged use (i.e., >24 hours); no cyanide accumulation
Antihypertensive Medications Used in Hypertensive Emergencies
Sodium Nitroprusside
Sodium nitroprusside:
Onset of action: <1 minute; activity loss within 10 minutes of discontinuation
Limitations: cyanide/thiocyanate toxicity: altered mental status, lactic acidosis that may occur within 4 hours
Antihypertensive Medications Used in Hypertensive Emergencies
Sodium Nitroprusside
Risks: high dose, prolonged use >24 hours, poor kidney function
For high doses (i.e., 10 mcg/kg/min):
Do not use >10 minutes.
Add sodium thiosulfate as sulfur donor to detoxify cyanide into thiocyanate.
Excessive hypotension may reduce coronary, renal, and cerebral perfusion.
NOTE
Sodium nitroprusside and nitroglycerin can potentially increase ICP and reduce cerebral perfusion.
Antihypertensive Medications Used in Hypertensive Emergencies
Calcium channel blockers (CCB)
Clevidipine: ultra-short-acting dihydropyridine CCB (half-life 1 minute)
Metabolizes in blood and intravascular tissues by esterases, safe for both kidney and liver failure patients.
Contraindicated in patients with aortic stenosis (potential severe hypotension), dyslipidemia (mixed in lipid-laden emulsion), and known allergies to soy or eggs
Nicardipine: longer onset of action and longer elimination half-life (3 to 6 hours)
Antihypertensive Medications Used in Hypertensive Emergencies
Selective dopamine-1 agonist: fenoldopam
Antihypertensive that can maintain or increase renal perfusion
Avoid in patients with glaucoma and sulfite sensitivity
Antihypertensive Medications Used in Hypertensive Emergencies
β-blockers
Labetalol:
Combined β- and α-adrenergic blocker: good for patients with acute coronary syndrome. Nonetheless, prior administration of α-blockers (e.g., phentolamine) should be done prior to using labetalol in patients with increased adrenergic states (e.g., PHEO, methamphetamine overdose, tyramine ingestion in patients on monoamine oxidase inhibitor).
Avoid in patients with asthma, COPD, acute heart failure, 2° or 3° heart blocks and bradycardia
Antihypertensive Medications Used in Hypertensive Emergencies
β-blockers
Esmolol: cardioselective β-blocker with short half-life and duration of action (9 and 30 minutes respectively)
Antihypertensive Medications Used in Hypertensive Emergencies
Hydralazine:
Intravenous form (arteriolar vasodilator, with possible reflex sympathetic stimulation, i.e., tachycardia)
Avoid in patients with coronary artery disease or aortic dissection.
Antihypertensive Medications Used in Hypertensive Emergencies
Enalaprilat (intravenous form of enalapril, angiotensin converting enzyme inhibitor): may cause excessive hypotension in hypovolemic patients
Suggested Medical Therapy for Specific Clinical Conditions
Acute aortic dissection: intravenous labetalol or esmolol, followed by nicardipine or nitroprusside as needed. Goals: SBP < 100 to 120 mm Hg, heart rate < 60
Suggested Medical Therapy for Specific Clinical Conditions
Acute pulmonary edema: nitroglycerin, enalaprilat, or nitroprusside drip. Intravenous furosemide as needed for hypervolemia. Goal BP reduction: 20% to 30%
Suggested Medical Therapy for Specific Clinical Conditions
Acute coronary syndrome: nitroglycerin drip, β-blockers such as metoprolol or labetalol bolus therapy. Goal: limit BP reduction to 20% to 30% for SBP > 160 mm Hg
Suggested Medical Therapy for Specific Clinical Conditions
Acute sympathetic crisis (cocaine, amphetamines): intravenous benzodiazepine and nitroglycerin or phentolamine drip, or intravenous verapamil bolus. Goal: symptomatic relief.
Suggested Medical Therapy for Specific Clinical Conditions
Acute kidney injury (AKI): labetalol bolus or nicardipine or fenoldopam drip. Goal: BP reduction ≤ 20%
Suggested Medical Therapy for Specific Clinical Conditions
Severe preeclampsia, eclampsia, HELLP syndrome: labetalol bolus, oral nifedipine or nicardipine. Goal: BP < 160/110 mm Hg, or <150/100 if platelet count < 100,000/mm3.
Suggested Medical Therapy for Specific Clinical Conditions
Hypertensive encephalopathy: nicardipine, labetalol, or fenoldopam drip. Goal: decrease MAP by 15% to 20%
Suggested Medical Therapy for Specific Clinical Conditions
Subarachnoid hemorrhage: labetalol, nicardipine, or esmolol drip. Goal: SBP < 160 mm Hg or MAP < 130 mm Hg
Suggested Medical Therapy for Specific Clinical Conditions
Intracranial hemorrhage: labetalol, nicardipine, or esmolol drip. Goal: MAP 130 mm Hg if increased ICP to maintain cerebral perfusion pressure, otherwise MAP 110 mm Hg
Suggested Medical Therapy for Specific Clinical Conditions
Acute ischemic stroke: labetalol or nicardipine drip. Goal: <185/110 mm Hg if fibrinolytic therapy planned
Suggested Medical Therapy for Specific Clinical Conditions
Acute postoperative HTN: Manage pain, anxiety; evaluate acute bleed at surgical site. Nicardipine, labetalol, or esmolol drip. Goal: preoperative BP
