Inotropes are the agents that effect force of contraction of heart.They increase mean arterial pressure by increasing the cardiac output.

1. INOTROPES AND
VASOPRESSORS

2. INOTROPES Definition:
 Agents that effect force of contraction of heart
 Types:
 Positive inotrope: Increase heart contractility thus increase heart rate.
 Negative inotropes: Decrease heart contractility thus decrease heart rate.
 Most commonly used are those with positive inotropic effect..

3. INOTROPES CONTINUE..
 Inotropes increase mean arterial pressure by increasing
cardiac output.
 MAP= CO × SVR
 CO= HR × SV
 HR is dependent on stroke volume.
 Stroke volume is dependent on preload and afterload.

4. Vasopressors Definition:
 Agents that increase mean arterian pressure by causing
vasoconstriction.
 Vasoconstriction results in increase in systemic vascular
resistance(SVR)
 MAP= CO × SVR
 SVR= 80× (Mean arterial pressure-mean venous
pressure/cvp)

5. Physiology
 Ionotropes stimate sympathetic nervous system.
 Receptors include:
Receptors Location Effect
a1 • Vascular walls
• Heart
• Vasoconstriction
• Inc. Duration of
contraction
B1 • Heart • Inc. contractility
B2 • Blood • Vasodilation
Dopamine • Renal splanchnic
• Coronary vessels
• Cerebral vessels
• Vasodilation

6. Drugs commonly used:
Drugs Receptor Actions
1. EPINEPHRINE (Adrenaline) 1. B1 at low dose (.05-.1
ug/kglmin)
2. a1 at high dose (>.1ug/kglmin)
1. Increase cardiac contractility
2. vasocontriction
2. Nor-epinephrine 1. a1 (Predominant)
2. B1 (weak)
1. Vasoconstriction
2. Increase myocardial
contractility
3. Dopamine 1. Dopamine (low dose 2-
5ug/kg/min
2. B1 (medium dose 5-
15ug/kg/min)
3. a1 (high dose >20ug/kg/min)
1. Increase renal blood flow
2. Increase cardia contractility
3. Vasoconstriction

7. Continue..
Drugs Receptor Actions
4. Dobutamine 1. B1 (Predominant) 1. Increase cardiac contraction
thus increase heart rate
5. Milrinone PDE inhibitor -> increased
Camp activity
1. Increase heart contractility
2. Vasodilation (decrease
SVR and preload)

8. Complications
 1. Hypoperfusion
 2. Dysrhythmias
 3. Myocardial ischemia
 4 hyperglycemia (more commonly with epinephrine and
norepinephrine)