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- Aug 22, 2013
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Okay so I just did that UW question regarding changes with phenylephrine. Got it right but only because it was the answer that made the most sense - I still didn't think it was correct but everything else was less correct.
Anyway, so UW says phenylephrine should increase SVR, increase SBP, decrease pulse pressure, and decrease HR. I understand this even though it goes completely against what first aid says and what sketchy pharm says (first aid says it should increase SBP more than DBP and thus increase pulse pressure, and I believe sketchy pharm says no change in pulse pressure).
What I don't understand is UW's explanation as to WHY we get a decreased pulse pressure. It says the increased BP --> baroreceptor mediated increase in vagal tone causes a decrease in both HR and in stroke volume. Thus, "the pulse pressure is decreased by phenylephrine because of the reflex decrease in stroke volume and the increased afterload".
I thought the baroreceptor reflex just affected heart rate?
Can someone explain this to me?
Anyway, so UW says phenylephrine should increase SVR, increase SBP, decrease pulse pressure, and decrease HR. I understand this even though it goes completely against what first aid says and what sketchy pharm says (first aid says it should increase SBP more than DBP and thus increase pulse pressure, and I believe sketchy pharm says no change in pulse pressure).
What I don't understand is UW's explanation as to WHY we get a decreased pulse pressure. It says the increased BP --> baroreceptor mediated increase in vagal tone causes a decrease in both HR and in stroke volume. Thus, "the pulse pressure is decreased by phenylephrine because of the reflex decrease in stroke volume and the increased afterload".
I thought the baroreceptor reflex just affected heart rate?
Can someone explain this to me?
