Upload
garey-green
View
222
Download
2
Tags:
Embed Size (px)
Citation preview
Activation of alpha-1 ◦ Postsynaptic adrenoreceptors located in smooth
muscle throughout the body◦ Increases intracellular calcium concentrations
Blood vessels: Vasoconstriction Pancreas: Inhibits the release of insulin Intestine/Bladder: Relaxation, but constriction of sphincters
Activation of alpha-2◦ Presynaptic receptors decreases NE release thru
negative feedback Brain receptors lowers the blood pressure (decreases SNS
activity) and causes sedation
Beta-1◦ Located primarily on post synaptic membranes of the heart
Positive chronotrope, dromotrope, and inotrope◦ Fat Cells: Lipolysis
Beta – 2◦ Located primarily on post synaptic smooth muscle and
gland cells Blood Vessels: Vasodilation Bronchioles: Bronchodilaton Uterus: Relaxation of uterus Kidneys: Renin Secretion Liver: Gluconeogenesis, glycogenolysis Pancreas: Insulin secretion
Dopamine-1◦ Blood Vessels: Dilates renal, coronary, and
splanchnic vessels
Dopamine-2◦ Presynaptic endings: inhibits NE release◦ CNS: Psychic disturbances
Phenylephrine◦ Primarily direct alpha-1 agonist with minimal beta affects
Arteriolar vasoconstriction Dose 50-200mcg bolus Duration 5 minutes PROS:
increases CPP without increasing myocardial contractility (useful in CAD, hypertrophic subaortic stenosis, or aortic stenosis
CONS: Decreased SV due to increased afterload, may increase PVR, may
decrease perfusion to kidneys, gut and extremities
Ephedrine◦ Mild direct alpha, beta -1 and beta-2 agonist◦ Primarily causes indirect release of NE◦ Dose 5-10mg IV bolus◦ Duration 3-10min◦ PROS:
Easy to titrate and rarely produces unexpected exaggerated response, does not reduce perfusion to placenta, ideal solution to correct sympathectomy induced hypovolemia and decr SVR
◦ CONS: Efficacy is reduced when NE stores are depleted Risk of malignant hypertension if used with MAOi Tachyphylaxis with repeat doses
Norepinephrine◦ Primary postganglionic sympathetic neurotransmitter◦ Direct alpha 1&2 and beta-1◦ Starting Dose .05-.5 mcg/kg/min IV infusion via
central access only◦ PROS:
Direct agonist, redistributes blood flow to the brain and heart because all other vascular beds are constricted
◦ CONS: Reduced organ perfusion: risk of ischemia to kidneys,
gut, liver, skin and extremities, causes pulmonary vasoconstriction, arrhythmias, and possible skin necrosis with extravasation
Epinephrine◦ Catecholamine produced by the adrenal medulla◦ Direct alpha 1&2, and beta 1&2◦ Peripheral vasoconstriction increases diastolic
pressure◦ PROS:
Direct acting, potent alpha and beta activity gives max effects and give equivalent increases in SV, less tachycardia after heart SX than other ionotropes, effective bronchodilator
◦ CONS: Tachycardia and arrhythmias, potential organ ischemia
including MI, increases PVR
Dose(mcg/kg/min) Receptors Activated
SVR
0.01-0.03 Beta May decrease
0.03-0.15 Beta >alpha Variable
0.15-0.5 Alpha 1 + Beta Increased
Dopamine◦ Direct alpha 1 and beta 1&2… and dopaminergic agonist◦ Indirect action : releases stored NE◦ Pros:
increases renal perfusion and urine output at low doses, BP response is easy to titrate due to its mixed vasopressor/inotropic effects
◦ Cons: response can diminish when NE stores depleted,
sinus/atrial/ventricular tachycardia or arrhythmias may occur, max inotropic effect less than epi, skin necrosis may occur w/ extravasation, MVO2 increases, and MI may occur if coronary blood flow doesn’t increase simultaneously, incr BP at higher doses may be detrimental to failing heart
DopamineDose (mcg/kg/min) Receptors Activated Effect
1-3 Dopaminergic (DA1) Increased renal & mesenteric blood flow
3-10 Beta 1 & 2 (plus DA1) Incr HR, CO, contractility, and PVR decreased SVR
>10 Alpha (plus beta&DA1) Increased SVR, PVR,HR, arrhythmiasDecreased renal blood flow and poss CO
Vasopressin◦ Endogenous antidiuretic hormone that produces
direct peripheral vasoconstriction thru V1 receptors◦ Pros:
effective in increasing SVR in severe acidosis, sepsis, and after CPB, cerebral vasodilator, may restore CPP after cardiac arrest without producing tachycardia
◦ Cons: Unpleasant symptoms in awake patients( abd cramping,
uterine contractions, nausea, bronchoconstriction, skin pallor, incr liver enzymes and perfusion to gut with prolonged use, decr plts, lactic acidosis
Utilized to suppress ventricular ectopy Lidocaine
◦ Depresses automaticity by reducing slope of phase 4 depolarization
Amiodarone◦ Na, K, Ca, alpha, and beta blocking properties◦ Stabilizes atrial and ventricular membranes◦ Utilized in ACLS for refractory VF and dysrhthmias◦ May causes hypotension and bradycardia
Atropine◦ Vagolytic effect enhances sinus node automaticity and AV
conduction Sodium Bicarbonate
◦ No longer routinely utilized in ACLS Use restricted to arrest associated with hyperkalemia, pre-
existing metabolic acidosis, tricyclic/phenobarbital ◦ Cons: metabolic alkalosis, hypernatremia, hyperosmolarity
Calcium◦ Increases contractility and increases ventricular
automaticity◦ CaCl produces higher and more consistent levels of
ionized calcium than other salts