Hypertensive crisis Flashcards
- What is a hypertensive crisis?
A hypertensive crisis is clinical symptoms characterized by severe elevations in BP leading to vascular injury and organ damage. These crises can be divided in to 2 general categories: hypertensive emergencies and hypertensive urgencies.
- What is a hypertensive emergency?
A severe hypertensive emergency is one with signs of damage to target organs (brain, CVS, kidneys). Immediate BP reduction is required with IV drugs.
DBP → greater than 150 mmHg in a healthy person or greater than 120 mmHg in individuals with pre-existing complications (ex. cerebral hemorrhage, aortic stenosis)
- What are causes of hypertensive emergencies?
- essential HTN
- renal parenchymal disease
- renovascular disease
- pregnancy (eclampsia)
- endocrine – ex. pheochromocytoma, Cushing’s, renin-producing tumors
- drugs – ex. cocaine, crack, sympathomimetics, amphetamines, MAO-inhibtors, tyramine
- drug withdrawal – ex. Clonidine, nifedipine, etc
- CNS disorders – ex. injury, stroke, tumor
- Autonomic hyperreactivity
- What is a hypertensive urgency?
Very high BP without target-organ damage. This is an acute complication and it is unlikely that immediate BP reduction is required. Rather pts should be started on 2-drug oral combination therapy and close evaluation should be continued on an outpatient basis.
- How are hypertensive emergencies managed?
- ICU admission with IV administration of drugs
- Arterial line to measure BP
- BP should progressively reduce using short-acting titratable IV drugs
- Avoid abrupt decrease in BP as they can lead to MI, stroke, or visual changes
- (1) lower BP no more than 25% within min to hour (2) if stable, follow up with further reduction towards goal of 160/100 mmHg within the next 2-6 hrs and make it to normal over next 8-24 hrs
- What are the 3 most important drugs that treat hypertensive emergencies?
- sodium nitroprusside
- labetalol
- fenoldopam
- What is Sodium Nitroprusside?
This is the drug of choice for hypertensive emergencies. It is always given via IV and has a 1-2 minute half life, therefore requiring continuous infusion. It leads to prompt vasodilation (arterial and venous SM) and reflex tachycardia.
- What are adverse effects of Sodium Nitroprusside?
- hypotension, goose bumps, abdominal cramping, nausea, vomiting, headache
- cyanide toxicity → nitroprusside metabolism produces cyanide ions – this can be treated with sodium thiosulfate infusion
- What is Labetalol?
This is a combined a- and B-blocker given via IV bolus or infusion for hypertensive emergencies. It has a half-life of 3-6 hours. A positive is that it does not cause reflex tachycardia. It is contraindicated for pts with asthma, COPD, pts with 2nd or 3rd degree AV blocks or bradycardia.
- What is Fenoldopam?
Peripheral dopamine-1 (D1) receptor agonist that evokes arteriolar dilation. It is given via IV infusion for hypertensive emergencies. It has a half-life of about 30 minutes and maintains or increases renal perfusion as the BP lower thereby promoting naturesis. It is safe to use in all hypertensive emergencies – esp those with renal insufficiencies. This drug is contraindicated for glaucoma.
- What is Nicardipine?
Calcium channel blocker that is given via IV infusion for hypertensive emergency. It has a half life of 30 minutes and evokes reflex tachycardia as normal vasodilators would do.
- What is Nitroglycerin?
Vasodilator that effects veins more than arteries. It is the drug of choice for hypertensive emergencies in pts with cardiac ischemia or angina, or after cardiac bypass surgery. It has a half life of about 2-5 minutes and hypotension is the most serous side effect.
- What is Diazoside?
Arteriolar dilator that prevents vascular smooth muscle contraction by opening K+ channels and stabilizing membrane potential. It has a half life of about 24 hrs. Its adverse side effects include hypotension, reflex tachycardia, sodium and water retention. It inhibits insulin release and therefore can be used to treat hypoglycemia secondary to insulinoma.
- What is phentolamine and Esmolol?
Phentolamine → drug of choice for pts with catecholamine-related emergencies
Esmolol → used for aortic dissection or postoperative hypertension
