Question about Pulse pressure!

[EthanHunter]

PP=Systolic-Diastolic (according to Goljan's notes). To me anything that increase systolic or decrease diastolic (increase HR or Contractility) would narrow the widen PP. But he used the scenerio of decrease TPR as in widen PP. For example; Thiamine def, endotoxin, warm shock. All these would vasodilate and decrease TPR, which decrease systolic and lead to Narrow pp. So why is this widen PP? Furthermore, explain that he used in the notes for narrow PP is increase TPR Via HTN, and late stage of shock? If someone can explain this to me, i appeciate very much. Thanks

[bigkap87]

Those are examples of high output cardiac failure, so you would have an increase in CO (initially for endotoxic shock and chronically for the rest) which would increase systolic BP and as you explained before decrease BP and widen the PP.

[EthanHunter]

oh ok so it's the compessation states of decrease preload. But is it vasoconstriction is the first reflex via Baroceptors to increase TPR? So why is it still decrease TPR?

[bigkap87]

I don't want to tell you the wrong answer but I do know in anemia, vasodilation occurs as the body tries to compensate for decreased oxygen delivery by increasing flow. In endotoxic shock, at first CO increases (not sure why) and then decreases it could be due to reflex tachycardia, but the main thing is all vessels lose their ability to constrict due to IL-1 TNF-a. Hope this helps.