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  #1  
Old 08-01-2012
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EKG Treatment of Resistant SVT!

A 59-year-old man with chronic obstructive pulmonary disease (COPD) and an irregular heartbeat is taken to the emergency room and found to have paroxysmal supraventricular tachycardia (PSVT). Intravenous treatments with adenosine and verapamil failed to re-establish sinus rhythm. Which agent would be appropriate to administer intravenously to abolish the PSVT in this patient?

a) Epinephrine
b) Esmolol
c) Norepinephrine
d) Phenylephrine
e) Terbutaline
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Old 08-02-2012
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confused between B and D.......tough one
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Old 08-02-2012
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iv esmolol - preferred but this pt has copd, so i"m confused
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Old 08-02-2012
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Give esmolol. Why would you want to give phenylephrine?
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Old 08-02-2012
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Quote:
Originally Posted by curiousmind View Post
iv esmolol - preferred but this pt has copd, so i"m confused
@ curiousmind
That's more reason you should give esmolol;it has no inhibitory effect on b2
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Old 08-02-2012
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Originally Posted by smanthrav View Post
Give esmolol. Why would you want to give phenylephrine?
phenylephrine---alpha1 agonist--increased TPR--->reflex parasympathetic tone increase--->increased AV node refractory period

i was thinking this way too, so got confused
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Old 08-03-2012
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Correct Answer correct answer :)

yeah, this one is a bit tough...

The answer is d) Phenylephrine - the explanation given by anomali is good
Phenylephrine is a vasopressor that is administered parenterally. It increases blood pressure by increasing peripheral resistance via stimulation of α1-adrenergic receptors. Phenylephrine is given by intravenous injection to cause a robust pressor response resulting in a profound reflex vagal effect for the treatment of PSVT.

As for esmolol - Esmolol, a very-short-acting β1-selective antagonist, is administered via continuous intravenous infusion for the acute control of PSVT. However, it is contraindicated in patients with pulmonary diseases, such as bronchial asthma, acute bronchospasm, or COPD because of potential β-adrenergic inhibition of bronchodilation with high doses.


When we learn about beta-blockers they recommend not to prescribe it to patients with asthma, COPD whether it's cardioselective or not. If we have to give beta-blockers, we give cardioselective. But it's only when we MUST give a beta-blocker. In this question they gave us the alternative, so I think that's why the answer is phenylephrine.
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Old 08-03-2012
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Quote:
Originally Posted by Casandra View Post
yeah, this one is a bit tough...

The answer is d) Phenylephrine - the explanation given by anomali is good
Phenylephrine is a vasopressor that is administered parenterally. It increases blood pressure by increasing peripheral resistance via stimulation of α1-adrenergic receptors. Phenylephrine is given by intravenous injection to cause a robust pressor response resulting in a profound reflex vagal effect for the treatment of PSVT.

As for esmolol - Esmolol, a very-short-acting β1-selective antagonist, is administered via continuous intravenous infusion for the acute control of PSVT. However, it is contraindicated in patients with pulmonary diseases, such as bronchial asthma, acute bronchospasm, or COPD because of potential β-adrenergic inhibition of bronchodilation with high doses.


When we learn about beta-blockers they recommend not to prescribe it to patients with asthma, COPD whether it's cardioselective or not. If we have to give beta-blockers, we give cardioselective. But it's only when we MUST give a beta-blocker. In this question they gave us the alternative, so I think that's why the answer is phenylephrine
.
well explained......u have brought a drastic change in my approach towards analyzing and answering questions.....so indebted to you
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well explained......u have brought a drastic change in my approach towards analyzing and answering questions.....so indebted to you
I'm glad it helps I know for sure that I'm learning a lot from those questions!
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Old 08-03-2012
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wow anomali's right!! looks like you're ready for the test, mate.

I thought it'd be okay to use sotalol since the question stem says he got adenosine...and thats contraindicated in asthma too!
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Old 08-03-2012
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Quote:
Originally Posted by smanthrav View Post
wow anomali's right!! looks like you're ready for the test, mate.

I thought it'd be okay to use sotalol since the question stem says he got adenosine...and thats contraindicated in asthma too!
Important point: this patient has COPD not asthma (a bit different mechanism of narrowing the bronchies ). COPD is not a CI for adenosine therapy. As for asthma:

Asthma traditionally an absolute CI this is being contended and it is now considered relative (however, selective adenosine antagonists are being investigated for use in treatment of asthma

(source: Wikipedia: http://en.wikipedia.org/wiki/Adenosi...traindications)

The article providing more details: http://www.ncbi.nlm.nih.gov/pmc/arti...tool=pmcentrez


you give it in hospital settings only but of course caution is recommended when administering adenosine. if a pt has a history of SVTs and had profound dyspnea after adenosine then verapamil is an alternative.

before you administer adenosine you warn the patient that dyspnea may occur/worsen. but what is more important is to tell the patient that they will feel as if they heart stopped - bc it does in a way, even up to 10-12 sec.

if a pt is taking theophyline adenosine may increase it's toxicity (risk of VTach) - that's the common/overlap point here for asthma and COPD.
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