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^ Above is partially right:
Propranolol is non-selective Beta blocker:
Beta1 stimulation causes inc HR, therefore blocking it will dec HR and dec Cardiac output
Beta 2 stimulation causes vasodilation, therefore blocking it will CAUSE UNOPPOSED alpha1 activation --> therefore increasing total peripheral resistance.
so why tf do we give beta blockers for hypertension -.-
I would also add that the patient was previously on an a2 inhibitor (clonidine), which he ran out of. So he is rebounding on that with upregulated a1 receptor activity. Adding labetalol would cause a greater degree of unopposed alpha, increasing tpr
@amarousis They are used for hypertension because the hypotensive effect of the reduced CO is greater than that of the effect of the increase of TPR. Cheers.
Would pheo have a normal resting BP though?
I was trying to justify these tricky questions but very true medschul.. It shouldn't have normal resting BP. Sometimes it seems these NBME always have a trick up their sleeve. Im getting paranoid lol
The reason why the patient probably has normal HTN is because Pheochromocytoma has symptoms that occurs in "spells" - they come and go. Apparently in that moment, when the physician is examining her, she doesn't have the HTN, but like @meningitis explained, so many adrenergic hormones around leads to double the vasoconstriction when the patient stands up.
Thank you @nala_ula for your contribution! Really filled in the gap Iwas missing.
No problem! Thank you for all your contributions throughout this page!
I thought the pheochromocytoma was getting squeezed during sitting and releasing the epinephrine then. kinda like how it can happen during manipulation during surgery. Got it right for sorta wrong reasons then oh well.
When she sits in the examination table there would be a normal activation of the sympathetic system from the stress of getting examined which is amplified by the pheo. Cheers.