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20 Cards in this Set
- Front
- Back
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Equations for Blood Pressure
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BP = CO x SVR
BP = [LVEDV-LVESV] x HR x SVR |
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A patient's blood pressure depends upon:
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How full the heart gets at the end of diastole
How empty the heart gets after systole - How strong the heart can contract - How difficult it is to eject the blood from the LV The appropriate heart rate The degree of vascular resistance to blood flow |
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How can receptors change in terms of inactivation?
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Uncoupling
Invagination / Reduction of number Chemical changes / inactivation |
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Alpha 1 Receptors
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Peripheral and splanchnic vasculature
- Few in heart muscle Smooth muscle contraction Vascular constriction (Pressor effect) |
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Alpha 2 Receptors
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Peripheral and splanchnic vasculature
- Different density from α1 receptors - Smooth muscle contraction - Vascular constriction (Pressor effect) Pre-synaptic receptors - Negative feedback Central Nervous System - Roles in pain and sedation |
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Beta 1 Receptors
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Cardiac tissue (stimulation causes…)
- Inotropic effect (cAMP) - Chronotropic effect – all tissues - Lusitropic (relaxation) effect Peripheral vasculature - Smooth muscle relaxation / vasodilation (cGMP modulated) Pre-synaptic receptors - Positive feedback |
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Beta 2 Receptors
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Cardiac tissue
- Normally β1: β2 is 4-6:1 - CHF ratio is 1-1.5:1 (Perhaps targeting β2 is better for CHF) - Same effects in heart as β1 Peripheral vasculature - Smooth muscle relaxation / vasodilation Bronchial smooth muscle - Relaxation / Bronchodilation |
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Dopamine Receptors
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Cardiac tissue (2 types)
- Inotropic, chronotropic Peripheral vasculature Splanchnic vasculature - vasodilation Renal (? 5 types) - Multiple effects, esp diuretic, natriuretic Central Nervous System (? 6-7 types) - Clearly involved in many pathways |
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Vasopressin Receptors
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Peripheral vasculature
- Marked vasoconstriction Splanchnic vasculature - Marked vasoconstriction (May be more pronounced than α1) |
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The primary function of Alpha-receptors?
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vasoconstriction (and afterload)
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The primary function of Beta-receptors?
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inotropy, chronotropy, vasodilation
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The primary function of DA-receptors?
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- splanchnic vasodilation, renal, CNS
- other effects |
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The primary function of V-receptors?
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vasoconstriction
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EPINEPHRINE
(Adrenaline) |
“God’s inotrope”
- β-effects predominate up to 0.1 μg/kg/min (5-7 μg/min) - α-effects at ~0.1 μg/kg/min - Inotropic & Chronotropic (Myocardial O2 demand is real problem) Sepsis, Cardiogenic Shock, post-CABG |
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DOBUTAMINE
(Dobutrex) |
- Inotrope with Vasodilating effects
- β-mediated effects - Increases contractility & heart rate - Vasodilates and reduces afterload - Inotropic & Chronotropic (Myocardial O2 demand may be less of problem) Acute MI, mild cardiogenic shock |
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NOREPINEPHRINE
(Levophed) |
“God’s pressor”
- α-effects predominate - β-effects are present (Maintain contractility against more afterload) - Vasoconstriction & increased SVR Sepsis, Distributive shock with good CO |
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PHENYLEPHRINE
(Neosynephrine) |
“Pure” α-agonist
- Essentially no β-effects - Vasoconstriction & increased SVR (Without the support of cardiac function) Mild Sepsis, Hypotension with good CO |
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DOPAMINE
(Intropin) |
- Dose-Dependent Pharmacology
- DA stimulation 0.5-3 μg/kg/min - β-effects 2-10 μg/kg/min - α-effects 7-20 μg/kg/min - “Dial-a-Drug” Not used with much frequency |
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VASOPRESSIN
(Pitressin) |
- Intense vasoconstriction through V-receptors
- No α- or β- stimulation (Non-adrenergic vasoconstrictor; No direct cardiac effects) - May have predilection for splanchnic vessels (Beware gut ischemia) ACLS, Severe shock, CABG (on ACEi) |
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PHOSPHODIESTERASE INHIBITORS
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Milrinone & Amrinone
- Vasodilators & Inotropes - Augments β-adrenergic stimulation - Smooth muscle relaxation (Hypotension (SVR)) CABG, Vasoconstricted with low CO |
