Decreased Contractility

Characteristics

• Decreased CO/CI

• Decreased SV/SI

• Increased SVR

• Variable BP

• Decreased SvO2

• Ventricular Dysfunction

• myocardial ischemia/infarction

• cardiomyopathy

• myocardial depression (sepsis)

Treatment

• Improve ventricular performance

• Expected Response

• increased CO/CI

• increased SV/SI

• decreased CVP/PAWP

• decreased SVR

• improved tissue perfusion

• Inotropic Agents

• dopamine

• dobutamine

• aminrone

• milrinone

• digoxin

Contractility Enhancers

• Stimulate beta receptors to increase inotropic state of the heart

Dobutamine

• Beta receptor stimulant

• Dose 1 to 20 mcg/kg/min

• Titrate to effect (increase CO/CI, SV/SI, SvO2)

• May lower BP & SVR

• Side effects

• tachycardia

• increased myocardial workload

• hypotension

Dopamine

• Stimulates both alpha & beta receptors

• Hemodynamic effect dose dependent

• Low-dose 1mcg to 5mcg/kg/min: improves renal & mesenteric blood flow

• Mid-dose 5mcg to 10mcg/kg/min: improves contractility

• High-dose: 10mcg to 20mcg/kg/min: increases SVR and BP

Phosphodiesterase Inhibitors

• Act by increasing intra-cellular calcium

• Inhibiting degradation of cyclic AMP

• May be useful if sympathetic stimulation (alpha & beta) is not effective

• Milrinone (Primocor)

• loading dose 0.05 mg/kg over 10 minutes

• continuous infusion 0.0375 to 0.75mcg/kg/min

• Titrate to improve SV/SI, CO/CI, & SvO2

• May lower SVR & BP

• Side effects: hypotension, thrombocytopenia

 

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