Cardiogenic shock help please!

[theTruth_97]

so I came across a question in one of the Qbanks about what's the next best step in a patient who has Right Ventricular MI and cardiogenic shock. The answer was to give them fluids

I'm somewhat confused by that choice because wouldn't fluids worsen the situation for the patient- with cardiogenic shock the patient has High Right Atrial pressure and high PCWP and low cardiac index so wouldn't giving them fluids just cause there to be more fluid that the heart can't pump?

I'm obviously messing up some concept so if someone can help me I'd really appreciate it. Thank you!

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[Nabin]

The basic strategy is to do a fluid challenge (provided no features of RHF or pulmonary congestion) and if the patient's RV filling pressures don't improve and shock persists, you'd have to consider ionotropic (Dopamine). The situation here is that RV filling pressures have increased due to the ischemic, stiff RV. Also, there is some degree of systolic dysfunction of RV. This can decrease cardiac output overall as LV preload is also decreasing simultaneously. Also, elevate RV filling pressures can cause the interventricular septum to shift and compromise the systolic function of LV. Normally filling pressures, preload and afterload improve after administering isotonic saline in most cases.

 

[cbrons]

so I came across a question in one of the Qbanks about what's the next best step in a patient who has Right Ventricular MI and cardiogenic shock. The answer was to give them fluids

I'm somewhat confused by that choice because wouldn't fluids worsen the situation for the patient- with cardiogenic shock the patient has High Right Atrial pressure and high PCWP and low cardiac index so wouldn't giving them fluids just cause there to be more fluid that the heart can't pump?

I'm obviously messing up some concept so if someone can help me I'd really appreciate it. Thank you!

The basic strategy is to do a fluid challenge (provided no features of RHF or pulmonary congestion) and if the patient's RV filling pressures don't improve and shock persists, you'd have to consider ionotropic (Dopamine). The situation here is that RV filling pressures have increased due to the ischemic, stiff RV. Also, there is some degree of systolic dysfunction of RV. This can decrease cardiac output overall as LV preload is also decreasing simultaneously. Also, elevate RV filling pressures can cause the interventricular septum to shift and compromise the systolic function of LV. Normally filling pressures, preload and afterload improve after administering isotonic saline in most cases.

"Give them fluids" would be such a stupid answer if the etiology of cardiogenic shock was undetermined, and of course USMLE would test something like RV failure-induced cardiogenic shock because its probably 1% of cases of MI-induced CS. But at any rate in this specific instance you give fluids to "optimize" their right atrial pressure. That would be the textbook answer.

Of course it would seem to me that there is a fine line between "optimizing" RAP and causing left-sided heart failure through mechanisms previously mentioned (IV septum LV shift, etc.)

If shock persists, you give Levophed (norepinephrine). Dopamine shouldn't be given to anyone for anything.

 

[theTruth_97]

The basic strategy is to do a fluid challenge (provided no features of RHF or pulmonary congestion) and if the patient's RV filling pressures don't improve and shock persists, you'd have to consider ionotropic (Dopamine). The situation here is that RV filling pressures have increased due to the ischemic, stiff RV. Also, there is some degree of systolic dysfunction of RV. This can decrease cardiac output overall as LV preload is also decreasing simultaneously. Also, elevate RV filling pressures can cause the interventricular septum to shift and compromise the systolic function of LV. Normally filling pressures, preload and afterload improve after administering isotonic saline in most cases.

thank you for taking the time to answer my question!

 

[theTruth_97]

"Give them fluids" would be such a stupid answer if the etiology of cardiogenic shock was undetermined, and of course USMLE would test something like RV failure-induced cardiogenic shock because its probably 1% of cases of MI-induced CS. But at any rate in this specific instance you give fluids to "optimize" their right atrial pressure. That would be the textbook answer.

Of course it would seem to me that there is a fine line between "optimizing" RAP and causing left-sided heart failure through mechanisms previously mentioned (IV septum LV shift, etc.)

If shock persists, you give Levophed (norepinephrine). Dopamine shouldn't be given to anyone for anything.

thanks for the help!

but why wouldn't dopamine ever be given?

 

[Nabin]

There are some findings suggesting Dopamine use may be associated with incidence of arrythmias compared to NE as @cbrons tried to point out in the reference article. But none of the studies show any concrete advantage of using one vasopressor over the other. Dopamine is considered second line to NE in patients with relative bradycardia and a low risk of tachyarrythmias. The alpha-receptor effect of Dopamine is weaker than that of NE and in practice, you need to carefully increase Dopamine doses in concordance with hemodynamic monitoring, so if one is not careful about the dosing effects of dopamine and its varied effect on different receptors, arrythmias may result from that. Hope @cbrons can further enlighten us on this.

 

[cbrons]

thanks for the help!

but why wouldn't dopamine ever be given?

It's proarrythmic, difficult to titrate, and also expensive.
The old idea was that dopamine was better bc it didn't require central venous access. Of course we now know that norepi doesnt require a central line up to a certain dose. But try suggesting giving Levophed peripherally to your attending, they might think you're an idiot when the truth is they haven't stayed up to date on the research.

http://www.ncbi.nlm.nih.gov/pubmed/26014852

http://www.scancrit.com/2015/06/10/peripheral-noradrenaline/

 

[Instatewaiter]

so I came across a question in one of the Qbanks about what's the next best step in a patient who has Right Ventricular MI and cardiogenic shock. The answer was to give them fluids

I'm somewhat confused by that choice because wouldn't fluids worsen the situation for the patient- with cardiogenic shock the patient has High Right Atrial pressure and high PCWP and low cardiac index so wouldn't giving them fluids just cause there to be more fluid that the heart can't pump?

I'm obviously messing up some concept so if someone can help me I'd really appreciate it. Thank you!

The issue is that with RV failure from an RV infarct, your RV cardiac output is low enought that you underfill the LV. You are in cardiogenic shock because your LV is underfilled so the PCWP is LOW in RV failure. This is different than left sided failure causing shock (high PCWP). So, you need to "overfill" the RV to fill the LV. Their PCWP is NOT high. It is low. Therefore, giving fluids is the right answer.

In terms other treatment besides just fluid, first, revascularize. In terms of support, dobutamine and milrinone tend to be our first lines because they give you more RV support.