When the heart is unable to meet the needs of the body, then the heart has failed. Whether the cause is due to myocardial infarction, valvular disease or arrhythmia. Heart failure is inadequate maintenance of blood pressure and or blood flow. Potential Energy (PE) is blood pressure and Kinetic Energy (KE) is blood flow. SMII is a measure of the heart’s energy or power.

1. The Measure of Lifewww.uscom.com.au
Inotropes, Inotropy, SMII
and Heart Failure
High Output Cardiac Failure

2. The Measure of Lifewww.uscom.com.au
Smith Madigan Inotropy Index
(SMII)
• When the heart is unable to meet the needs of the
body, then the heart has failed
• Whether the cause is due to myocardial infarction,
valvular disease or arrhythmia
• Heart failure is inadequate MAINTENANCE of blood
pressure and or blood flow - CI < 2.4 l/min/m2
• Potential Energy (PE) is blood pressure and Kinetic
Energy (KE) is blood flow.
• PE + KE = SMI ; SMI / BSA = SMII
• SMII is a measure of the heart’s energy or power

3. The Measure of Lifewww.uscom.com.au
Septic Shock
Presentation to ED
84 year old
BP 74/38 mmHg
MAP 50 mmHg
Treatment decision
• Should the patient be started on fluids?
• Is this patient a fluid responder?
• How will this patient respond to a vasopressor?

4. The Measure of Lifewww.uscom.com.au
Septic Shock
USCOM Exam Results
• SVI 86 ml/m2
• HR 113
• CI 9.1 l/min/m2
• SVR 181 d.s.cm-5
• DO2 2609 ml/min

5. The Measure of Lifewww.uscom.com.au
Cardiac Reserve
• To treat low BP with a vasopressor (e.g.
phenylephrine) it is important to know the SMII
and if there is myocardial inotropic reserve to
cope with the increase in afterload, otherwise
the ventricle will fail.

6. The Measure of Lifewww.uscom.com.au
Septic Shock
USCOM Exam Results
• SVI 86 ml/m2
• HR 113
• CI 9.1 l/min/m2
• SMII 0.77 W/m2
• SVR 181 d.s.cm-5
• DO2 2609 ml/min

7. The Measure of Lifewww.uscom.com.au
Underlying Heart Failure
• High SVI, Low SMII, Low SVR
• SMII 0.77 = Left ventricular failure
• SVR 181 = Decompensated vascular collapse
• High output heart failure - septic shock
• This shows severe myocardial depression, but
with such a low afterload the underlying heart
failure was not obvious!

8. The Measure of Lifewww.uscom.com.au
Heart Failure
• SMII of 0.77 W/m2 is typical for LVF patients
• It means that the heart is on a flat Starling curve
and is essentially unresponsive to volume
expansion alone
• Management must increase the inotropy of the
heart simultaneously with volume expansion if
fluid is required

9. The Measure of Lifewww.uscom.com.au
High Output Heart Failure
• To raise BP we must use a vasoconstrictor with
positive inotropic properties
Treatment
• Start Noradrenaline at
• 200 ng/kg/min

10. The Measure of Lifewww.uscom.com.au
Low Output Heart Failure
USCOM
• BP 114/62 mmHg
• MAP 79 mmHg
• SVI 23 ml/m2
• SMII 1.1 W/m2
• DO2 652 ml/min
SVI low, SMII low, SVR high
Add dobutamine at 8 mcg/kg/min

11. The Measure of Lifewww.uscom.com.au
Normalizing Hemodynamics
USCOM
• BP 122/66 mmHg
• MAP 85 mmHg
• SVI 34 ml/m2
• SMII 1.48 W/m2
• DO2 1018 ml/min
↑Dobutamine 10mcg/kg/min
↓NA to 150ng/Kg/min

12. The Measure of Lifewww.uscom.com.au
Hemodynamic stability
USCOM
• BP 124/62 mmHg
• MAP 83 mmHg
• CO 6.1 l/min
• SMII 1.56 W/m2
• SVR 744 d.s.cm-5
• DO2 1162 ml/min

13. The Measure of Lifewww.uscom.com.au
Summary
• Optimizing hemodynamics in septic shock
saves lives
• Use of inotropes is a difficult clinical skill
• Accurate and advanced hemoydnamics
improves guidance of inotropes and
supporting therapy

14. The Measure of Lifewww.uscom.com.au
Conclusion
USCOM
• Measures the total energy or load on the heart
• Identifies patients who need inotropes for SVI
and CI optimization
• Determines which inotrope to use
• SVI, SMII and SVRI values guide appropriate,
effective and rapid treatment