Flashcards in Meds Deck (18)
What are the functions of Ca++?
1) Cardiac action potential
2) Increase FOC, smooth muscle contraction
3) Blood clotting factor in coag cascade
4) Bone density
What is calcium gluconate indicated for, and how is it given?
For electrolyte replacement.
1-2g IV in 100cc D5W over 1 hr
What is the corrected calcium calculation and why is it used?
50% of calcium is ionized but 45% bound to albumin and 5% to other elements
Corrected Ca++ = Ca(m) + [0.02 x (40-alb) ]
What is calcium chloride used for, and how is it given?
For severe hypocalcemia, hyperkalemia, Ca++ channel blocker OD, cardiac arrest, CRRT protocol
1g in 100cc D5W CVC over 1 hr or push
Must administer centrally, pre loaded syringe available
How is calcium gluconate and calcium chloride different?
Calcium chloride has 3x the elemental / ionized calcium, used for emergencies, centrally administered, can be pushed via pre-filled syringe
What class of drug is dopamine?
Sympathomimetic, inotrope, vasopressor
What are the doses of dopamine and effects?
1) Low / Dopaminergic / Renal ( < 3 mcg/kg/min) mild renal vasodilation, increase U/O
2) Moderate / Intermediate / Beta (3 - 10 mcg/kg/min) Beta-1 selective, cardiac inotrope cronotrope dromotrope
3) High / alpha / pressor (10 - 20 mcg/kg/min)
Alpha selective, vasoconstriction
When is dopamine indicated and how is it given?
Acute severe hypotension, sepsis (4th line), symptomatic bradycardia (but dobutamine and milrinone are better)
400mg in 250cc --> 5mg/kg/min titrate (start at beta dose)
What must be considered when given inotropes?
Inotropes increase FOC. Hypovolemia must be resolved first so that the heart has something to pump
What is dobutamine's drug class?
Sympathomimetic inotrope, beta 1 selective mild beta 2
What is the effect of dobutamine?
Inotropic, mild vasodilation
Increase FOC, CO, decrease afterload and preload
Does dobutamine affect renal vessels?
No. Any increase in U/O is related to increase GFR and CO
When is dobutamine indicated and how is it given?
Reversible heart failure / post op, shock, CHF, pharmacologic stress testing
5 - 15mcg/kg/min given centrally
What are nursing considerations for dobutamine and milrinone?
Little change to HR so good med for cardiac patients, but high doses will cause tachycardia and arrhythmias from enhanced AV conduction. Fix hypovolemia
What is milrinone's drug class? What is its mechanism of action?
Cardiac inotrope, vasodilator
Inhibits phosphodiesterase type III which is an enzyme that destroys cAMP (regulates Ca++ passage to heart). Inhibition therefore overall raises the level of Ca++ in the cardiac cells and increases FOC as well as allows mild vasodilation in vasculature resulting in increased SV
When is milrinone indicated and how is it given?
Reversible heart failure / post op, shock, CHF, weaning off cardiopulmonary bypass
Loading: 50mcg / kg over 10-15 mins
Continuous: 0.25 - 0.75 mcg/kg/min
Mix 20mg in 80mls D5W/NS to give 100 mls
What are the similarities and differences between dobutamine and milrinone?
Increase FOC, CO, SV
Decrease afterload, preload
Use central line
Good for cardiac patients (not chronotropic) but can cause tachycardia at high doses
Sympathomimetic vs Cardiac inotrope
Beta 1 selective vs enzymic inhibition
Milrinone has loading dose and LONG half life (2-4hrs)