The use of vasopressors and inotropes to treat hypotension is common in the emergency department. It is now standard to start off with norepinephrine as your 1st line agent to treat shock in the ED. But is norepi always that best choice? What if you need a second agent?
Treatment of hypotension should be based on the etiology of shock. The following are simple recommendations for which inotropes and pressors are best to use based on different types of shock. The following assumes blood and fluids have been given where appropriate.
Septic Shock: Everyone knows norepinephrine is the 1st line agent. Dopamine may have a small indication for use over norepi in a highly select population but this is more advanced and not necessary for the average EM physician. This article is an excellent demonstration of multiple previous studies which have shown a higher mortality and higher incidence of arrhythmic events when dopamine is used. Most clinicians will reach for either epinephrine or vasopressin as the preferred second line agent. I think it is ideal to perform a bedside echo prior to starting your second agent to assess cardiac function. If evidence of dysfunction, epinephrine may be preferable for the additional inotropic support. If cardiac function seems appropriate, vasopressin at a fixed dose may be appropriate to achieve the desired MAP and decrease norepinephrine concentrations. This is the algorithmic approach from emcrit.
Cardiogenic Shock: The hypotensive patient in cardiogenic shock can be terrifying. These patients have high mortality. Although many will benefit from pci or mechanical support, we need to medically support them in the emergency department until such interventions are available. The primary problem is cardiac output failure, therefore inotropy is crucial for these patient. Your best options for inotropy are either epinephrine or dobutamine. Dobutamine generally will cause some hypotension and typically will be paired with norepinephrine (a weak inotrope). It is tempting to use a single agent, epi, in these patients but you shouldn’t. Studies (study 1, study 2) seem to show worse outcomes with epinephrine alone compared to norepi and dobutamine.
Anaphylactic Shock: Epi, Epi and Epi are first line.
Hemorrhagic Shock: NO PRESSORS – blood as quickly as you can in a 1:1:1 fashion