Q. why CO decreases in CNS injury? - USMLE Forums
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Old 08-01-2016
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Default Q. why CO decreases in CNS injury?

Q. In CNS injury ( distributive shock), Preload, Cardiac output, and afterload all decreases ( From FA 2016,p 292).
Preload & afterload must have decreased due to vasodilation but I didn't understand why Cardiac output also decreases. Is there any explanation for decrease in cardiac output.thanks.
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fa 2015 considers CNS injury shock just like septic shock.But 2016 makes more sense as: if you have a CNS injury your body wont be able to increase the CO .
The basic principle we consider is to mantain the MAP: (MAP=CO*TRP) in case of septic shock body will sense the decrease in MAP and cause a compensatory increase CO due to decrease in TPR. But it wont be able to do the same in CNS injury as your control center for MAP is present in medula.
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