graphical display of the hemodynamic effects of different cardiac inotropes
Inotropes are medications that augment cardiac output (CO)
- Chronotropic effect - affects the rate of cardiac contraction (heart rate; HR)
- Inotropic effect - affects the force of cardiac contraction (stroke volume; SV)
Additionally, many inotropes also affect systemic arteriolar vascular tone or afterload. We can describe inotropes in terms of their effects on systemic vascular resistance (SVR) as either:
- Inodilators - inotropes that decrease SVR
- Inoconstrictors - inotropes that increase SVR
In order to understand how these effects interact, recall two important physiology concepts:
The combination of increased CO and decreased SVR can either increase or decrease mean arterial pressure (MAP); for this reason. even though inotropes increase cardiac output, the effects of inodilators on blood pressure can be complex.
In order to help understand the physiolgical effects of inotropes I made the following visualizations using RStats plotly and htmlwidgets libraries:
I also made a Shiny app version which you can play with here.
- for more see the Critical Care Time podcast I recorded about this!