Postive Inotropes Flashcards
(104 cards)
1
Q
What is the defintion of shock?
A
Peripheral circulatory failure resulting in underperfusion of tissues
2
Q
Shock results from decreased ____ delivery to tissues and an increase in ____ metabolism
A
- O2
- Anaerobic
3
Q
3 types of shock
A
- Septic
- Cardiogenic
- Hypovolemic
4
Q
Septic shock is the the result of ____ CI, ____ PCWP, and _____ SVR
A
- Increased
- Decreased
- Decreased
5
Q
Hypovolemic shock is the the result of ____ CI, ____ PCWP, and _____ SVR
A
- decreased
- decreased
- increased
6
Q
Cardiogenic shock is the the result of ____ CI, ____ PCWP, and _____ SVR
A
- decreaed
- increased
- increased
7
Q
CHF is the result of decreased _____
A
intracellural cAMP
8
Q
What two processes are responsible for the the decreased intracellular cAMP in CHF?
A
- Downregulation of Beta receptors
2. Impaired coupling between beta receptors and adenyl cyclase
9
Q
CHF responds to what 3 treatments?
A
preload reduction, afterload reduction, and improved contraction
10
Q
The risk Low Cardiac Output Syndrome (LCOS) increases if a patient is on CPB longer than ___-
A
6 hours
11
Q
Risk factors for developing LCOS
A
- DM
- Increased age
- Female
- Pre-op decreased LVEF
- Increased duration of CPB
12
Q
LCOS is a combination of what 7 factors?
A
- Inadequate oxygen delivery to tissues
- Hemodilution
- Mild hypocalcemia
- Hypomagnesemia
- Kaliuresis
- Tissue thermal gradients
- Variable levels of systemic vascular resistance
13
Q
What is the pathophysiogy of LCOS?
A
Stunned myocardium (hypocontractile myocardium in response to ischemia and reperfusion)
Beta receptor down-regulation has been reported
14
Q
What is the treatment of LCOS?
A
Positive inotropes to increase the contractility of normal and stunned myocardium
Hypotension, unlike CHF, responds poorly to vasodilators alone.
15
Q
What are the 2 goals of LCOS?
A
Increase levels of O2 delivery (keep SvO2 >70%)
Increase O2 consumption (arterial blood lactate level < 2 mmol/L).
16
Q
T/F
LCOS is similar to cardiogenic shock
A
True
17
Q
What are the two major classes of positive inotropes?
A
cAMP Dependent and cAMP independent
18
Q
What drug classes are contained in cAMP dependent positive inotropes?
A
- Beta Agonists
- Dopaminergic Agonists
- Phosphodiesterase Inhibitors
19
Q
What drug classes are contained in cAMP independent positive inotropes?
A
- Cardiac Glycosides
2. Calcium
20
Q
What are the hemodynamic effects of positive inotropes that are “pure” beta 1 agonists?
A
- Increased HR
- Increased A-V conduction
- Decreased SVR and PVR (Beta 2 effects)
- Variable effect on MRO2 (dependent on HR effect)
21
Q
Which drug has the most arrhythmogenic potential?
A
Isoproterenol>Epinephrine>Dopamine>Dobutamine
22
Q
What enzyme stops contraction and breaks down cAMP into AMP?
A
Phosphodiesterase
23
Q
MOA of cAMP dependent Positive inotropes?
A
Catecholamine binds to beta receptor and activates membrane bound guanine nucleotide. This activates AC which generates cAMP. cAMP increases CA++ and therefore increases the force of contraction and velocity of relaxation
24
Q
Which receptors are stimulated at low-dose epi?
Intermediate-dose epi?
High-dose epi?
A
Low dose= Beta 2
Intermediate dose=Beta 1
High dose= Alpha 1
25
What epi dose would ideally be used to a patient with low cardiac output?
Intermediate dose epinephrine.
26
What receptors are activated by norepinephrine?
Alpha-1>Beta 1>Beta 2
27
T/F: Cardiac output may decrease at low doses, but at high doses may increased because of increased afterload and baroreceptor mediated reflex bradycardia with norepinphrine infusion?
False; CO increases with low dose, and can decrease with high dose
28
Which medication can be given along with norepinephrine to produce predominantly Beta 1 agonism from the NE only?
Phentolamine
29
Why might NE be used following cardio-pulmonary bypass?
to be used as a vasoconstrictor to counter the vasoplegic syndrome that can follow CPB
30
What are complications of catecholamine administration
1. Local tissue ischemia from SQ infiltration
2. Increased MRO2
3. Enhanced lipolysis and gluconeogenesis
4. Alter electrolytes
5. Activate coagulation
6. Override microvascular control mechanisms
7. Alter distribution of CO
8. Increase myocardial work
9. Increase the risk of cardiac arrythmias
31
Which receptors does isoproterenol stimulate?
Beta-1 and Beta-2
32
What is the net effect of isoproterenol on CO and MAP?
```
CO Increases
MAP Decreases (d/t drop in SVR)
```
33
Does the diastolic or systolic BP change with isoproterenol infusions?
Systolics may stay the same (or mildly elevate), but diastolics will decrease
34
What is the reason for diastolic/MAP decrease with isoproterenol infusions?
It is due to Beta-2 agonism
35
What are the 3 main uses of isoproterenol?
1. Chemical pacemaker after heart transplant or in complete heart block
2. Bronchospasm management during anesthesia
3. Decrease PVR in patients with pulmonary hypertension and RV failure
36
Name a synthetic catecholamine with structural characteristics of dopamine and isoproterenol?
Dobutamine
37
Dobutamine works on which receptors?
Beta 1>>>beta 2=alpha 1
| Almost primarily Beta 1
38
What is dobutamine's effect on coronary vasculature?
Dilates coronaries
39
Is dobutamine effective in patients with septic shock?
No; not effective d/t the need for increased SVR to increase BP
40
Dobutamine should only be mixed in what IV solution?
D5W
41
D1-like or D2-like:
| Stimulates adenylate cyclase?
D1-like
42
D1-like or D2-like:
| Causes naturesis and diuresis?
D1-like
43
D1-like or D2-like:
| vasodilation?
Both
44
D1-like or D2-like: Inhibits cAMP?
D2-like
45
What other dopamine receptors are "like" D1?
D5
46
What other dopamine receptors are "like" D2?
D3, D4
47
What other positive inotrope does dopamine mimic in it's incremental receptor effects?
Epinephrine
48
What is the infusion rate for "renal dose" dopamine?
0.5 to 3mcg/kg/min
49
What is "renal dose" dopamine's effect on the kidneys?
Increase RBF, GFR, Na+ excretion, and UO, but is not renal protective
50
What are the effects typically seen from dopamine infusion at 2-10mcg/kg/min?
Beta receptor effects
51
Are there indirect or direct effects from beta receptor agonism with dopamine?
Both. Indirect effects increase release of NE stores
52
At doses greater than 20mcg/kg/min, dopamine has primarily what effect?
Alpha receptor effects
53
In what three clinical situations is dopamine typically used?
1. Decreased CO
2. Decreased systemic BP
3. Increased LVEDP
54
What is dopamine's effect on breathing?
Dopamine inferferes with the ventilatory response to hypoxemia
55
What is dopexamine's use?
Treat CHF when SVR is high
56
What are the effects seen with dopexamine infusions?
1. Beta 2 activity
2. D1 activity
3. Inhibits presynaptic reuptake of NE
57
What are fenoldopam's effects?
1. Selective D1 agonist
2. Alpha 2 agonism
3. Decrease SVR
4. Dose related increase in RBF
58
T/F: Fenoldopam is 10-100 times more potent than Dopamine?
True
59
Is fenoldopam a renal protective?
No, preserves RBF and UO
60
What is unique about the administration of IV fenolodopam compared to other positive inotropes?
1. A-line not required
| 2. Can use peripheral IV
61
What are 4 cautions with fenoldopam infusions?
1. Dose related tachy with infusions >0.1mcg/kg/min
2. Hypokalemia
3. Costly
4. Slight increase IOP
62
Are phosphodiesterase inhibitors cAMP dependent or independent?
dependent
63
What are the cellular effects of PDE3 inhibitors?
1. Slow the metabolism of cAMP to 5-AMP with increases intracellaulr cAMP
2. Increase Ca++ sensitivity of contractile proteins
3. Increase Ca++ influx
64
What are the overall hemodynamic affects of PDE3 Inhibitors?
1. Peripheral, arterial, venous vasodilation
| 2. Increased CO
65
Inamrinone is effective at treating poor LV function; however, what other drug can be administered at the same time to improve outcome?
Epinephrine
66
What are adverse side effects with Inamrinone?
1. *Thrombocytopenia*
2. Elevated LFTs
3. Arrythmias
67
Inamrinone is absolutely contraindicated with which diagnosis?
Aortic stenosis
68
Which drug has inotropic and vasodilator properties and is similar to inamrinone?
Milrinone
69
Which side effect is NOT related to Milrinone, but is a side effect of inamrinone?
No risk of thrombocytopenia with Milrinone
70
What are the SEs of milrinone?
1. H/A, HoTN, syncope
2. Ventricular arrhythmias
3. Increased ventricular response rate in Afib/flutter
71
Which drug act at a receptor other than the beta to increase cAMP?
Glucagon
72
MOA of Glucagon?
Activates Glucagon receptor and through G-protein 2nd messengers, it accelrates AC and increase cAMP.
73
Where is Glucagon secreted from in the body?
Alpha Pancreatic cells
74
What arrhythmia is glucagon specifically helpful in treating?
Brady-arrhythmias and beta-blocker induced heart failure
75
What are the hemodynamic effects of glucagon?
Increase CI, HR, BP
| Decreases SVR and LVEDP
76
Why is glucagon's use limited?
Side effects: N/V, increased blood sugar, increased coronary and pulmonary vascular resistance
77
What medication class does digoxin belong to?
Cardiac Glycoside?
78
What are Digoxin's three major effects on CV system
1. Positive inotrope
2. Negative dromotrope
3. Negative chronotrope
79
What are the only two approved uses for digoxin?
1. Heart failure
| 2. Atrial fibrillation
80
Does digoxin primarily work on the SA or AV node?
AV node
81
MOA of Digoxin?
Digoxin stops the Na+ from leaving the cardiac cell so that less Na+ needs to come back in. Less Na+ movement means less Ca++ will leave the cell over all.
In a sentence, digoxin blocks the sodium which stops the calcium from leaving the cell
82
What is the therapeutic range for Digoxin?
0.8-2ng/ml
83
What EKG change can be seen with digoxin?
Swooping ST segment (expected and non-pathological)
84
At what level is digoxin considered toxic?
Plasma levels >3ng/ml
85
For what treatment is digoxin plasma level often above toxic levels?
When treating A fib. Treat to results (desired ventricular rate)
86
What are 5 predisposing factors for digoxin toxicity?
1. Hypokalemia
2. Hypomagnesemia
3. Hypoxemia
4. Hypercalcemia
5. Hypothyroid
87
What is the most frequent cause of death with digoxin toxicity?
V Fib
88
What is the most common dysrrythmia with digoxin toxicity?
Paroxysmal atrial tachycardia with Mobitz Type II block
89
Treatment for CV issues causes from digoxin toxicity?
1. Phenytoin/lidocaine to suppress ventricular dysrrythmias
2. Atropine to increase HR
3. Beta blocker
4. Temporary pacing for complete heart block
5. Digibind
90
How does digibind work?
Fragmented antibodies (FAB) bind to the drug and decrease the plasma concentrations of cardiac glycosides
91
How is FAB=digitalis complex eliminated from the body?
kidneys
92
What drugs enhance digoxin absorption?
1. Macrolides
2. PPIs
3. Conazoles
4. Ranolazine
93
What drugs decrease digoxin absorption?
1. Resin binders
2. Acorboes/miglitol
3. Kaolin-pectins
4. Reglan
5. Sulfasalazine
6. Sucralfate
94
3 conclusions from ALARM-HF trial?
1. Lower in house mortality fro patients receiving vasodilator+diuretic vs diuretic alone
2. Great in house mortality for IV inotropes vs no inotropes
3. 1.5 fold increase for patients receiving dopamine or dobutamine, 2.5 fold increase for patients receiving NE or EPI
95
What are the step to treating low CO?
1. Appropraite heart rate (pacing)
2. Optimize ventricular filling (preload)
3. Reduce afterload if BP is appropriate
4. Improve contractility (inotrope)
5. Recheck adequacy of ventricular filling
6. Combination therapy (inotropes and vasodilators)
7. IABP
8. LVAD
96
What is the MOA of Levosimendan?
Increases the sensitivity of the myocardium to Ca+
Not approved in USA, but used to treat hypotension and arrhythmias from LCOS
97
Are pure beta-1 agonists (Isoproterenol, dobutamine) inodilators or inoconstrictors?
Inodilators
98
Are mixed alpha and beta agonists (NE, Epi, Dopamine) inodilators or inoconstrictors?
Inoconstrictors
99
What substance breaks down cAMP into AMP?
PDE3
100
What is the prototypical catecholamine?
Epinephrine
101
According to the Frank Starling curve, stroke volume improves with ______
Blood volume
102
T/F
Dopexamine is a inoconstrictor
False
It is a inodilator
103
T/F
When starting Fenoldopam, you need to start with a bolus dose
False
DO NOT BOLUS
104
T/F
MAP will stay the same with low dose epinephrine
True
