Hypertension Deck 1 Flashcards
Nitroprusside (Nipride)
Mechanism of Action
♦ A powerful vasodilator relaxes the vascular smooth muscle and produce consequent dilatation of peripheral arteries and veins.
♦ Sodium nitroprusside is more active on veins than on arteries.
Hydralazine
(mechanism of action)
♦ Causes direct dilation of arterial wall smooth muscle
♦ Hydralazine decreases B/P and reduces cardiac afterload
(result = decreased arterial blood pressure (diastolic more than systolic) and peripheral vascular resistance
Hydralazine
(onset and duration)
Hypotensive effects occur 5—30 minutes after an IV dose.
The antihypertensive effects of an IV dose last 2—6 hours on average
Hydralazine
(side effects)
♦ Hypotension
♦ Tachycardia
* The hydralazine-induced reflex autonomic response increases heart rate, stroke volume, cardiac output, and left ventricular ejection fraction
Hydralazine
(indications)
♦ Severe Hypertension
Hydralazine
(contraindications)
(Precautions), None Listed in Protocol
Hydralazine is excreted mainly in the form of metabolites in the urine. (hydralazine should be used with caution in patients with advanced renal damage)
When hydralazine is used in the presence of increased intracranial pressure, lowering of the blood pressure may result in increased cerebral ischemia.
Hydralazine
(adult dose)
♦ 5mg IV/IO over 2 minutes
may repeat
♦ to Max of 20mg
Hydralazine
(pediatric dose)
Not indicated in current protocols
Hydralazine
(pregnancy safe)
Pregnancy Class C
no adequate human studies have examined the effects of this drug on the fetus, the potential risks to the fetus must be weighed against the potential benefits to the mother.
The American Academy of Pediatrics considers hydralazine to be generally compatible with breast-feeding
Labetolol
(mechanism of action)
Beta Blocker
♦ Competively blocks beta receptors in the heart and blood vessels
♦ minimizes reduction in cardiac output while decreasing B/P
♦ has very little effect on cerebral circulation.
♦ Class II Antiarrhythmic
(**avoid using with cocaine toxicity**)
Labetolol
(onset and duration)
Onset: 2-5 min <> Duration: 16-18 hrs
The maximum effect of each intravenous labetalol dose occurs within 5 minutes.
An initial 0.25 mg/kg injection decreases blood pressure by an average of 11/7 mmHg.
Labetolol
(side effects)
Dizziness,
lightheaded,
headache,
nausea/vomiting,
chest pain,
shortness of breath,
fatigue
Labetolol
(indications)
> Hypertension <
Labetolol
(contraindications)
♦ Bronchial asthma - β2-adrenoceptors promote bronchodilation- (“beta blocker”) - increased risk for status asthmaticus
♦ overt cardiac failure - has negative inotropic effects; can cause acute left ventricular failure given in large doses to pt’s who have impaired function of the left ventricle
♦ cardiogenic shock - due to acute negative inotropic effects
♦ bradycardia - Labetolol slows heart rate
♦ hypotension - slows HR and decreases B/P
Labetolol
(adult dose)
♦ 20 mg IO/IV over 2 minutes
→ give additional 20→ 40→ 80 mg q 10 min PRN (in that progression)
Maximum dose of 300 mg
Labetolol
(pediatric dose)
Not indicated in current protocols