Hemodynamic Drips
Hemodynamic Drugs
-Drips are expressed differently at different institutions
-Often little data to show one pressor/inotrope better than the other
-Remember your receptors:
α – peripheral vasoconstriction
β1 – increased intotropy and chronotropy
β2 – systemic vasodilation
DA – renal/splanchnic/coronary/cerebral vasodilation
Vasopressors Increase perfusion to end organs as long as CO maintained
Phenylephrine (Neo-Synephrine) – α agonist;
-useful in low SVR states (sepsis/distributive shock)
-avoid in cardiogenic shock!
-great agent to use in sepsis when want avoid β agonism (arrhythmias)
Norepinephrine (Levophed) – α, β1 agonist;
-useful in both cardiogenic and septic shock + mixed pictures
-raises pulmonary arterial pressure (be careful with PHTN)
-arrhythmogenic
Vasopressin – Vasopressin receptors (non-adrenergic)
-careful with hyponatremia and gut ischemia!
Inotropes
-Necessary in low cardiac output states
-mechanism ultimately leads to Ca++ release -> inotropy/chronotropy -> incr CO
[pic]
β-agonists:
-most powerful way to increase contractility
-all arrhythmogenic
-desensitization develops when used continuously
Dobutamine β1, β2 agonist
-Advantage over dopa in heart failure – mild vasodilation (especially at lower doses)
-may actually drop BP initially (before CO rises)
-relatively weak and desensitization develops easily
Dopamine < 2μg/kg/min DA; 2-5 β, 5-20 α, β; > 20 α
-at low dose, theoretical selective vasodilation of renal arterial beds
-arrhythmias more pronounced
-at higher doses, peripheral vasoconstriction is more prominent
-in advanced HF, should only use lower doses for enhanced renal perfusion
Phosphodiesterase Inhibitor:
Milrinone – Phosphodiesterase inhibitor (see figure) in myocytes and vascular sm muscle
-more potent vasodilation than β-agonists (useful if very high SVR), careful if PCW low
-inotropic effect is inconsistent
-potent pulmonary artery vasodilator
-thrombocytopenia 0.4% (vs. 2-3% with amrinone)
-1/2 life is 2.3 hours (much longer than dobutamine)
-reduce dose in renal failure
Hemodynamic Effects of Inotropes
|Medication |Preload Reduct |Afterload Red |Contractility |Vasoconstrict. |
|Dopa(med)5-10 |- |- |++ |- |
|Dopa(high) >20 |- |- |++ |++ |
|Dobutamine |+ |++ |+++ |- |
|Milrinone |++ |++ |+++ |- |
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