Vasopressors M5/TL Flashcards
alpha 1 adrenergic stimulation causes constriction of …, …., …. and contraction of …, which all consistent with fight/flight response and therefore, its effect on metabolism is ….
BV, bronchus, sphincter,and ciliary muscle (mydraisis).
Urtine contraction.
suppressed insulin and lipolysis.
Why CO is slightly decreased with the large increase of afterload (vasoconstriction) with with alpha 1 agoinist meds?
Mild intopy resulted from cardiac alpha receptors stimulation.
Will Neo causes coronary vasoconstriction and feared to be administered in CAD?
Coronary arteries to left ventricle is only pressure during diastole (when aorta diastole pressure > LVEDP) and when Decreasing HR.
Neo accomplishments both
- yes it can constrict coronary but the metabolic vasodilator (NO) easily override the weak vasoconstriction
Pressor of choice to preserve kidney function in sepsis
NorEpi
Not dopamine
The reason of NorEpi gtt became first of choice in sever hypotension compared to dopamine is
Associated with lower rates of arrhythmias
Catecholamines metabolites?
VMA
It’s breaker down by COMT and MAO.
Patients on MAOI should theoretically need lower doses
Dobutamine works on both beta receptors and only one alpha receptor?
Beta agonist and alpha-1 agonist
Press that will increase CO with minimal HR change ….
And … increases HR the most.
Dobutamine.
Isoproterenol
Dromotropic Vs chronotrophy effect?
Conduction speed of electrical impulses within the heart.
Chronotrophy refers to HR.
Lusitropy vs inotropy
Lusitropy is the process of myocardial relaxation during diastole
Intoropy; contractility
Tachyphlaxis of ephedrine caused by …
Depletion of presynaptic NorEpi
Beta receptor stimulation leads too …. which converts ATP to …
Gs protein -> Andenylate cyclase -> Converts ATP to cAMP -> increase Ca
Milrinone MoA?
It inhibits the enzyme thatmetabolize cAMP and therefore keeping Ca levels high intercellular.
The enzymes phosphodiesterases
Causing vasodilation, decrease preload and afterload. Increases intropy, lusitropy and chronotrophy
Inhaled vasodilator to lower pulmonary artery pressure is
Nitric oxide (not nitrous; it increases plum artery pressure).
Nitric has minimal effect on systemic pressure because it metabolized quickly
Nitric oxide MoA ?
(+) guantlate cyclase -> increasing cGMP -> relaxes smooth muscle and vasodilation
(cGMP broken down by 5th isoform phosphodiesterase, which is sildenafil inhibits it)
Milrinone MoA
Causes SM vasodilation and decreases PVR by increasing intercellular cAMP
Selective PDE III inhibitor which impairs breakdown of cAMP and therefore increases intracellular cAMP -> leads to increased influx of intracellular Ca -> cardiac ionotropy
When Gulcagon considered therapy for low CO states
- following cardiopulmonary bypass.
- following MI
- chronic CHF
- low CO from excessive BB
- anaphylaxis shock with refractory hypotension
The pressor that should not be given IM, only through central line?
NorEpi
It causes local ischemia necrosis given its alpha receptors stimulation»_space; beta leading to potent vasoconstriction
Phentolamine solution of 5-10 mg in 10-15 NS decreases the degree of necrosis if happened.
Why Ephedrine can be given IM when compared to NorEpi and what’s the dose/action time?
Because it’s not a direct vasoactive and will not cause loca ischemi.
0.5-0.6 mg/kg increases BP and HR within 10-15 min from time of injection
Can phenylephrine given IM?
Yes because it’s less potent than NorEpi and causes venoconstriction»_space; arterial constriction.
Dose: 2-5 mg raises BP and lowers HR within 10-15 min from injection.
Vasodilator that can increase RBF?
Fenoldopam is a selective dopamine-1 agonist that increases renal blood flow.
At lower dose of dopamine (0.5 to 3 mcg/kg/min) primarily acts on … and produce …
D-1 dopamine receptors to produce vasodilation of the renal, mesenteric, and coronary vasculature. The main result is an increase in the glomerular filtration rate and renal blood flow. Furthermore, low dose dopamine will result in sodium excretion which will increase urine output.
Moderate doses of dopamine ( 3 to 10 mcg/kg/min) will stimulate the … and produce …
beta-1 receptors to increase release of norepinephrine from sympathetic nerve terminals. The end result is an increase in heart rate, systolic blood pressure, and pulse pressure. Diastolic blood pressure is minimally affected however pulmonary vascular resistance may increase.
Highest doses of dopamine ( >10 mcg/kg/min) will stimulate the … and produce …
alpha-1 receptors which results in peripheral vasoconstriction.
Side effects of dopamine depend on the dose and the patient’s comorbid conditions. Dopamine can cause …
tachyarrhythmias and myocardial ischemia.
At higher doses a decrease in splanchnic blood flow may occur with resultant gut ischemia.
Dopamine infusions may alter endocrine and immune functions including decreased secretion of thyroid stimulating hormone, prolactin, and growth hormone.
Dopamine decreases the ventilatory response to hypoxemia and hypercarbia secondary to exertion of a depressive effect on the carotid bodies.
Furthermore, dopamine may impair regional ventilation/perfusion matching in the lung, potentially causing or worsening hypoxemia.
If dopamine is extravasated, it can result in skin necrosis and sloughing thus administration into a central line is recommended. If extravasation does occur, prompt infiltration of the area with phentolamine and/or application of topical nitroglycerin should be considered to counter the vasoconstriction.
Glucagon MoA?
Glucagon activates adenyl cyclase to increase cyclic AMP levels. Glucagon increases cardiac index, mean arterial pressure, and ventricular contractility.
Intraoperative hypotension refractory to first line measures such as fluids, ephedrine, phenylephrine, and glycopyrrolate, think of? whats the most effective treatment?
Patients who continue ACEi/ARB on day of surgery.
Reversed with either norepinephrine or vasopressin, but only norepinephrine will do so while maintaining cardiac output and gastric perfusion.
Milrinone Effects:
- Intropy through …
- vasodilation through …
1) Cyclic AMP Effect: Inotropy
- Increases contractility (inotropy), heart rate (chronotropy) and conduction velocity (dromotropy).
- Increased cardiac output.
2) Cyclic AMP Effect: Vasodilation
- Smooth muscle relaxation.
- Decreased left ventricular end-diastolic pressure.
- Improves pulmonary blood flow and left ventricular filling.
The cardiovascular effects of milrinone can be summarized as:
increased inotropy
increased lusitropy
increased CO, SV, and EF
decreased afterload
decreased preload
pulmonary vasodilation, and systemic vasodilation.
