Positive Inotropes

Question 1

Shock

Answer 1

• peripheral circulatory failure resulting in underperfusion of tissues
• decreased oxygen delivery to tissues
• increased anaerobic metab (more acidic ph, increased lactate)

Question 2

Septic Shock

Answer 2

Increased CI
Decreased PCWP
Decreased SVR

Question 3

Hypovolemic Shock

Answer 3

Decreased CI
Decreased PCWP
Increased SVR

Question 4

Cardiogenic Shock

Answer 4

Decreased CI
Increased PCWP
Increased SVR

Question 5

CHF

Answer 5

end result of many conditions
(ischemic heart disease, HTN)
-decreased intracellular cAMP, downreg of beta receptors - impaired coupling of beta recept and AC

Question 6

CHF responds to….

Answer 6

preload reduction, afterload reduction, improved contraction

Question 7

LCOS: Risk Factors

Answer 7

Low cardiac output syndrome

risk factors: DM, increasing age, female, preop decreased LVEF, increased duration of CPB

Question 8

Pts coming off CPB…

Answer 8

inadequate o2 delivery to tissue, hemodilution, mild hypocalcemia, hypomagnesemia, kaliuresis, tissue thermal gradients, variable levels of SVR

Question 9

LCOS Patho

Answer 9

• stunned myocardium (hypocontractile myocardium in response to ischemia and reperfusion)
• Beta receptor down-regulation has been reported

Question 10

LCOS Tx

Answer 10

• positive inotropes to increase contractility of normal and stunned myocardium
• HoTN, unlike CHF, responds poorly to vasodilators alone

Question 11

LCOS Goal

Answer 11

in critically ill.. increase O2 delivery (keep SVO2 > 70%), increase O2 consumption (arterial blood lactate = 2 mmol/L)

Question 12

Positive Inotropes: cAMP Dependent

Answer 12

Beta Agonists
Dopaminergic Agonists
Phosphodiesterase Inhibitors

Question 13

Positive Inotropes: cAMP Independent

Answer 13

Cardiac Glycosides

Calcium

Question 14

Positive Inotropes: Hemodynamic Effects

Answer 14

increased contractility with increased SV and often decreased LVEDP and V

Question 15

Positive Inotropes: “Pure” Beta 1 Agonists

Answer 15

dobutamine, isoproterenol, inodilators

• increased HR, AV conduction -decreased SVR and PVR (B2)
• variable effect on MVO2

Question 16

Positive Inotropes: Mixed Alpha and Beta Agonists

Answer 16

NE, Epi, dopamine - inoconstrictors

• increased vascular resistance
• increased MVO2
• increased HR

Question 17

Positive Inotropes: Arrhythmogenic potential

Answer 17

Isoproterenol > Epi > DA > Dobutamine

Question 18

Phosphodiesterase III Inhibitors

Answer 18

• slow metabolism of cAMP to 5’AMP –> increaseing intracellular cAMP concentration
• increase Ca sensitivity of contractile proteins
• Increase Ca influx
• peripherally, arterial and venous vasodilation
• increased CO

Question 19

Epinephrine - Low Dose

Answer 19

B2
B2 in skeletal muscle/peripheral –> decreased SVR, no change in MAP

Alpha 1 at skin, mucosa and hepatorenal

Question 20

Epi - Mid Dose

Answer 20

B1 increased HR, contractility, CO, automaticity

Question 21

Epi - High Dose

Answer 21

Alpha 1 tx dose, vasoconstrict all over but no significant effect on cerbral arterioles

*maintains myocardial and cerebral perfusion

Question 22

Digoxin toxicity

Answer 22

associated with decreased intracellular K
early s/s: NV, anorexia,

PVCs, mobitz 2 block

V-fib - most frequent cause of death

Question 23

Predisposing causes of dig tox

Answer 23

hypokalemia
hypomag
hypoxemia
hypercalcemia
hypothyroid

Question 24

Most common arrhythmia with dog tox…

Answer 24

paroxysmal atrial tachy with block

Question 25

1st step to treat dig tox

Answer 25

correct cause - give K, mag supplement, correct hypoxemia

Question 26

Drugs for dig tox

Answer 26

lidocaine/phenytoin for arrhythmia
atropine to increase HR
beta blocker- effect may be limited by pos inotropic effect
may need to pace

Question 27

Digibind

Answer 27

bind and decrease plasma concentrations of drug
eliminated by kidneys
do not check levels!