 Welcome back to our med smarter question of the week and as always we start with the last sentence of the vignette which lets us know what this question is looking for. So what would have been observed following administration of epinephrine? A 29 year old female with pheochromocytoma is being treated with phenoxybenzamine prior to surgical excision of the tumor. After successful surgical removal of the pheochromocytoma the patient has an episode of hypotension requiring 30 seconds of cardiopulmonary resuscitation and subsequent treatment in the intensive care unit. The attending physician asks his medical students what physiologic responses he would expect to see if the patient had been given epinephrine during resuscitation. What would have been observed following administration of epinephrine? Take a minute, read the question, choose your answer, and write your answer in the comment box below. Alright so let's look through this and find out what are some of the information we need to know. Well we're talking about a patient that has a pheochromocytoma. They're being treated with phenoxybenzamine and the surgeon removes the pheochromocytoma shortly thereafter the patient went into hypotension and had to have CPR performed. So we're wanting to know if we gave epinephrine during this time where the patient was hypotensive which is a classic medication to push during CPR. What would have happened to this patient? Well so what we're going to be doing is trying to find out what is the relation of epinephrine to phenoxybenzamine specifically in relation to patients that have a pheochromocytoma that has been removed. Alright so with A the answer choice A decrease in blood pressure. So if you remember back to phenoxybenzamine what does phenoxybenzamine do? Phenoxybenzamine is a non-selective alpha antagonist and that works specifically on the alpha 1 and alpha 2 receptors. This does not have any effect on our beta receptors. Now epinephrine however is an agonist for both alpha and for beta receptors. So what we would have here is a unopposed beta agonization. So we would have agonistic effects for beta only with no alpha effects associated. So what would beta receptor effects only cause? Well we would see an increase in heart rate and an increase in contractility. We'll also see some vasodilation and bronchodilation. So our increase in heart rate and our vasodilation are going to be our two main things we're looking at based off of these answer choices. So will it decrease our blood pressure? Will that vasodilation will most certainly possibly decrease our blood pressure? So I think A might be an option. Does it decrease our heart rate? No. We're increasing heart rate because of increasing our heart contractility with our beta 1 agonist. So B is not a correct answer. Does it increase blood pressure? No because we're vasodilating. Does it increase our respiratory rate? No. We're actually bronchodilating. We're able to get more air in with our beta 2 effects. So D is not the correct answer. And then no changes in vital signs. We definitely know it's not the correct answer because we are having those unopposed beta 1 options. So in that case we're left with A as our only option and a decrease in blood pressure would be the final answer. And A is the correct answer here. As we mentioned phenoxybenzamine is a non-selective alpha antagonist. It's blocking alpha 1 and alpha 2. Epinephrine is an agonist for alpha 1, alpha 2, beta 1, beta 2. So if we're getting alpha 1, alpha 2 blocked we'll have the unopposed action of beta 1 which is our increase in heart rate and increase in contractility. And then we have our beta 2 which is causing vasodilation and bronchodilation. So our net effects here in this regard are increase in heart rate and decrease in blood pressure from the vasodilation.