11 Hypertensive Emergencies, part 2 Flashcards
Presentation of acute renal failure
patients may have
- peripheral edema
- oliguria
- loss of appetite
- nausea and vomiting
- orthostatic changes
- confusion
Elevated serum creatinine confirms the diagnosis
therapeutic goal for acute renal faiulre
reduce BP by no more than 20% acutely
Antihypertensive agents that are all suitable for acute hypertension-induced isolated renal failure
Fenoldopam (improves natriuresis and creatinine clearance)
Nicardipine
Clevidipine
These reduce systemic vascular resistance while preserving renal blood flow
Drugs to avoid in acute renal failure
Nitroprusside, as it results in cyanide and thiocyanate toxicity.
ACE inhibitors (in acute failure)
therapeutic goal for preeclampsia
Aim for SBP <140 mm Hg in the first hour
preferred agents for preeclampsia
hydralazine
labetalol
nifedipine
How to administer hydralazine
10 mg SIVP (max initial dose is 20 mg)
repeat every 4 -6 h as needed
AVOID in patients with myocardial ischemia, pulmonary edema, and aortic dissection. Reflex tachy increases myocardial demand
How to administer labetalol?
bolus: 10-20 mg IV over 2 mins;
may administer 40-80 mg at 10-min intervals,
up to 300 mg total dose
infusion: initially, 2 mg/min; titrate to response up to 300 mg total dose, if needed
may cause fetal bradycardia
risk in patients with asthma, COPD, and heart failure
remarks on labetalol
combined selective a1- adrenergic and non-selective B-adrenergic receptor blocker
a- to B-blocking ratio of 1:7
safe in pregnancy
4 settings in which an excess of catecholamines can result in a hypertensive emergency
a.k.a. “Acute Sympathetic Crisis”
- abrupt discontinuation of oral or transdermal clonidine
this withdrawal syndrome is potentiated by concomitant B-blocker therapy due to unopposed a-mediated vasoconstriction - pheochromocytoma
- Sympathomimetic drugs (e.g., cocaine, amphetamines, MAOI toxicity)
- autonomic dysfunction (d/t spinal cord or severe head injury or abn such as spina bifida)
Therapy goals for acute sympathetic crisis
Reduce excessive sympathetic drive
Symptomatic relief
Aim for SBP <140 mm Hg int he first hour
How to manage acute sympathetic crisis
In general, IV benzodiazepine (BZD) is first-line to decrease adrenergic stimulation
If BZD is ineffective, add nitroglycerine or phentolamine
calcium channel blocker is 3rd-line
For patients with pheochromocytoma in hypertensive emergency, IV phentolamine is first-line
first-line agent for cocaine-induced hypertension
benzodiazepines
drugs given in pheochromocytoma
IV phentolamine is first-line for patients with pheochromocytoma in hypertensive emergency
Phenoxybenzamine is a long-acting oral adrenergic a-receptor blocker, used only in the preoperative setting in patients who are hypertensive but not in crisis
For patients who have undergone fibrinolysis/thrombolysis for acute ischemic stroke, the BP goal for the first 24 hours is _______
≤180/105
(In contrast to the goal prior starting thrombolysis which is ≤185/110)
How to administer nicardipine?
start at a rate of 5 mg/hour.
If target BP not achieved in 5-15 mins, increase dose by 2.5 mg/hour every 5-15 mins
until target pressure or the max dose of 15 mg/hour is reached
nicardipine is a second-generation dihydropyridine calcium channel blocker with vascular selectivity for the cerebral and coronary arteries
precautions for nicardipine
avoid in patients with advanced aortic stenosis.
caution in decompensated heart failure.
avoid in patients receiving IV B-blockers (?)
nitroglycerin is a first-line agent only in the treatment of
acute heart failure and acute coronary syndrome
Nitroglycerin is a potent venodialtor, showing arterial dilatation only at very high doses.
the only available IV ACE inhibitor
Enalaprilat
has special application with heart failure or acute coronary syndrome
(monitor carefully because of first-dose hypotension)
Remarks on clonidine
a central a2-agonist
generally does NOT have a role in the treatment of patients with hypertensive emergencies except for those who have recently stopped taking the drug (for fear of clonidine withdrawal)
when used, 0.2-0.3 mg PO clonidine is a common start
Remarks on treatment of asymptomatic severe hypertension
There are reasons to initiate outpatient blood pressure reduction regimens prior ED discharge, such as:
- uncorrected hypertension is associated with an eventual increased risk of cardiovascular events and renal dysfunction
- if severe HTN is not addressed in the ED, patient may not seek further OPD BP management
*Ideal first choice medication in most patients with hypertensive urgency [as it is used once daily and is inexpensive]
Hydrocholorothiazide 25 mg PO
(but onset of action is delayed - 2 h)
*Outdated recommendation
recommended first-line oral antihypertensive for patients with:
heart failure
diuretic with ACE inhibitor
recommended first-line oral antihypertensive for patients with:
post-myocardial infarction
B-blocker, ACEi or ARB
