Sinai Empearl 4/4/13

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    Sinai Empearl 4/4/13

    Vasopressors and Inotropes in the Critically Ill Patient

     RECEPTORS:

     Alpha-1 adrenergic receptors are located in vascular walls, induces significant vasoconstriction

     Beta-1 adrenergic receptors are most common in the heart and mediate ionotropy and chronotropy  

     Beta-2 adrenergic receptors in blood vessels induces vasodilatation

     Dopamine receptors are present in the renal, splanchnic, coronary, and cerebral vascular beds- stimulation of which leads to vasodilatation.  A second subtype of dopamine receptors causes vasoconstriction by inducing norepinephrine release 

    1. Norepinephrine aka LEVOPHED

    FIRST LINE AGENT FOR SEPTIC SHOCK

    Action– acts on alpha -=1 and beta-1 adrenergic receptors thus producing vasoconstriction as well as modest increase in cardiac output

    Pros– Rapid BP control

    Cons–  Need a central line

                Pt’s limbs can turn purple with prolonged usage

    1. Vasopressin

    NOT TO BE USED AS A SINGLE PRESSOR. CONSIDER IN REFRACTORY SEPTIC SHOCK ONCE LEVOPHED REQUIREMENTS ARE MAXED.

    Action – Increases vascular tone via stimulating V1 receptor including potentiation of catecholamine pressor agents.

    Pros:   Well tolerated

                Can decrease dose of other pressors

    Cons:  Contraindicated theoretically in patients with CAD or mesenteric ischemia.

     

    1. Epinephrine 

    FIRST LINE IN ANAPHYLAXIS. CONSIDER IN EXTREME HEMODYNAMIC COLLAPSE

    Action– Potent beta-1 adrenergic, moderate beta 2 and alpha-1 receptor effects. This results in an increased CO, with decreased SV and variable effect on the MAP. However at higher doses the alpha-adrenergic receptor effect predominates, producing increased SVR leading o increased CO.

    Push dose courtesy of EMCrit: Take a 10 ml syringe with 9 ml of normal saline. Into this syringe, draw up 1 ml of epinephrine from the cardiac amp (amp contains Epinephrine 100 mcg/ml)Now you have 10 mls of Epinephrine 10 mcg/ml.

    Dose: 0.5-2 ml every 2-5 minutes (5-20 mcg)

    Onset: 1 minute

    Duration: 5-10 minutes

    Pros: should be push dose pressure of choice

    Cons: Dysrhythmias, splanchnic vasoconstriction

     

    1. Phenylephrine

    MOST FREQUENTLY UTILIZED IN ANESTHESIA INDUCED HYPOTENSION  

    Action-            Potent purely alpha adrenergic agonist resulting in vasoconstriction

    Push dose courtesy of EMCrit: Take a 3 ml syringe and draw up 1 ml of phenylephrine from the vial (vial contains phenylephrine 10 mg/ml). Inject this into a 100 ml bag of NS. Now you have 100 mls of phenylephrine 100 mcg/ml. Draw up some into a syringe; each ml in the syringe is 100 mcg

    Dose: 0.5-2 ml every 2-5 minutes (50-200 mcg)

    Onset: 1 minute

    Duration: 20 minutes

    Pros: can be used as push dose pressure

    Cons: may decrease SV, so is reserved for patients in whom

                          norephinephrine is contraindicated due to arrhythmia 

    1. Dopamine

    WITH ALL OF THE DRUGS WITHIN OUR ARMAMENTERIUM, THERE IS NO GOOD REASON TO NEED TO RESORT TO DOPAMINE

    Action– It is the immediate precursor of norepinephrine and epinephrine. 

    Different receptors for different doses

    0-5ug           dopaminergic receptors leading to vasodilatation of renal and mesenteric vascular beds. This “renal dose” is ineffective as a pressure agent

    5-10ug         B-adrenergic receptors lead to positive inotropic and chronotropic effects- you achieve increase in MAP through increase in SV and CO

    10-20ug/kg/min           alpha-adrenergic receptors lead to systemic vasoconstriction- this is your pressor effect

     

    Pros:               Can be given via peripheral line

                            It can be an effective pressor at higher doses.

                            Good if someone is bradycardic and hypotensive

    Cons:              Tachycardia (in 15% of patients who receive it)

                            May impair splanchnic blood flow at higher doses

                            Ineffective in acidosis

                            You’ll never need to use it

     

    INOTROPES

    1.  Dobutamine

    Action- Beta 1 activity (major), Beta 2 and alpha (minor). This results with

    increased CO with decreased SVR (+/- small reduction in blood pressure)

     Pros: used frequently in heart failure and cardiogenic shock

    Cons: not routinely used in sepsis because of risk of hypotension

     

                2. Milrinone    

    Action– A phosphodiasterase 3- inhibitor in cardiac and vascular muscle.  This inhibitory action is consistent with cAMP mediated increases in intracellular ionized calcium and contractile force in cardiac muscle, as well as with cAMP dependent contractile protein phosphorylation and relaxation in vascular muscle. Thus having inotropic and vasodiliatary properties.

    Pros: lower incidence of dysrhythmias

    Cons: Not to be used in the hypotensive patient

     

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