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NBME 24 Answers

nbme24/Block 1/Question#30

A 55-year-old man is brought to the emergency ...

Pulmonary capillary wedge pressure: increased;
Cardiac output: decreased;
Systemic vascular resistance: increased

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Patient has cardiogenic shock, specifically the LV since it’s an anterior wall MI isn’t pumping. Honestly you don’t need to know what happens to PVR to answer correct since the only choice that has increased SVR and decreased PCWP is the one w/decreased PVR. I’m not absolutely sure if you could figure it out given the values in cardiogenic shock. The equation linking the values is:

PVR = (pulmonary arterial pressure - wedge) ÷ CO

Why is it that the pulmonary capillary wedge preesssuree is increased? on pg. 307 of FA 2019 it says it can be increased or decreased :/

giggidy  Depends on where the infarct is I guess? Crackles in lung base means increased left sided pressure and therefore PCWP. At least that's how I thought of it. +1  
titanesxvi  Because think the circulation as a closed circuit, in this case the heart isn't pumping well and the pressure is going to backup. that is why the PCWP is increased +1  

davidw  If the Infarct was on the right side they you would have a decrease in PCWP +  
usmile1  yes exactly. Cardiogenic shock always has decreased CO and increased SVR. PCWP is the tricky part. If its right sided, there isn't enough blood making it to the LA (which is what PCWP measures) thus PCWP would decrease. If it is left sided, as indicated in this question by the crackles in the lungs, the blood is backing up in the left side of the heart so the PCWP would go up. +3  

Patient is in cardiogenic shock. Characteristic features of cardiogenic shock: increased cardiac pressures and decreased cardiac output due to impeded forward flow, as well as increased systemic vascular resistance