# Cardiac scenario



## rhan101277 (Feb 26, 2010)

This is a test question I got wrong tonight.  I want to see why the answer I chose was incorrect..



You are treating a patient with an acute MI and she begins developing increasing SOB.  Upon reassessment you notice the patient has developed an S3 heart sound and now has basilar rales.  VS BP 186/112, P118, R 24, O2 sat 96%.  Which of the following would be a good choice to administer next?

Selected Answer: Incorrect   Lasix 40mg IV

Correct Answer: 	Correct   Dobutamine 10mcg/kg/min 


I didn't consider doing a dobutamine infusion since blood pressure was already high, why make the heart work harder by using a powerful Beta 1 agonist?  I mean yeah it creates more squeeze without increased heart rate but there should be plenty of pressure to clear that fluid from the lungs with a dose of Lasix.

Thoughts?


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## 8jimi8 (Feb 26, 2010)

My best guess is because of decreased ventricular compliance, so they are implying that the dobutamine will strengthen the force of contraction and :. increase cardiac output.  I don't think that lasix is a bad answer, either in this case, but i'm still learning.  I'm also interested in other people's opinions.


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## rhan101277 (Feb 26, 2010)

8jimi8 said:


> My best guess is because of decreased ventricular compliance, so they are implying that the dobutamine will strengthen the force of contraction and :. increase cardiac output.  I don't think that lasix is a bad answer, either in this case, but i'm still learning.  I'm also interested in other people's opinions.



I don't think cardiac output needs to be increased due to the high blood pressure.  I think dobutamine would increase afterload, causing even higher pressure, causing the heart increased oxygen demand. Which makes no since ot me in an acute MI situation.  Perfusion seems good and O2 sats are ok, 96% isn't the best it can be but I'm not going to be chewing my nails off about it.


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## 8jimi8 (Feb 26, 2010)

hey, the answer could have been miskeyed.

Based on the scenario, that is my best guess.  But you also have to look at WHY is the blood pressure so high?  If there is ischemia due to blockage, the heart is trying to increase perfusion i.e. increased blood pressure.  Increasing force of contraction could help a failing heart to increase the ejection fraction ... thereby increasing cardiac output.  increased cardiac output leads to increased perfusion.

see where i'm going with this?  Like I said, i cannot explain your instructor's rationale, but that is the best I can come up with.  lasix would pull fluid off, which would decrease your preload.  if the heart is failing to perfuse, a reduction of preload doesn't logically seem to increase perfusion.

what is your rationale behind the lasix?  Like i said in my first post, lasix upon first reflection, seems to be a good answer.


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## 8jimi8 (Feb 26, 2010)

btw increasing force of contraction doesn't decrease afterload.  It is a solution for too much afterload.  Afterload is the resistance the heart must pump against to move blood out of the ventricle.  See my logic behind increasing FOC to increase perfusion?


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## Melclin (Feb 26, 2010)

The increased hydrostatic pressure is caused by left ventricular insufficiency so it makes perfect sense to increase the action of the left ventricle so dobutamine makes perfect sense. 

Regarding the hypertension, dobutamine is mild peripheral vasodilator so it actually decreases after load. Its also a given that this would be used in combination with nitrates so the high BP would hopefully not be an issue.


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## 8jimi8 (Feb 26, 2010)

and the learning continues!  thanks Meclin!  edited to add... if it is a pvd, why is one of the side effects HTN^ ?


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## Melclin (Feb 26, 2010)

> and the learning continues! thanks Meclin! edited to add... if it is a pvd, why is one of the side effects HTN^ ?



Couldn't tell you I'm afraid. I could speculate but its better to look it up. I don't know that much about it to be honest, we don't use it in the pre-hospital setting here. 

Here's a run down of what I was on about, maybe the answer is in there somewhere:

http://emedicine.medscape.com/article/157452-treatment 

Also, lasix takes quite a while to work  so its not going to fix the problem in the short term (or perhaps at all - its future as a treatment in APO is questionable) which is perhaps what the question was getting at when considering it to be a wrong answer. If I was asking that question, my answer would have been nitrates. What were the other options?


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## 8jimi8 (Feb 26, 2010)

Thanks for the link,

my drug cards didn't mention the peripheral vasodilation.  Although the link seems to link the presentation with PEdema and hypotension, I understand your perspective.


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## Veneficus (Feb 26, 2010)

*This is a classic cardiogenic shock scenario.*



rhan101277 said:


> This is a test question I got wrong tonight.  I want to see why the answer I chose was incorrect..
> 
> 
> 
> ...




Meclin also summed it up expertly.


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## MrBrown (Feb 26, 2010)

Quite interesting I must say


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## MrBrown (Feb 26, 2010)

double post wtf


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## 8jimi8 (Feb 26, 2010)

Veneficus said:


> Originally Posted by rhan101277
> This is a test question I got wrong tonight. I want to see why the answer I chose was incorrect..
> 
> 
> ...




Vene can you go into a little more about your reasoning in emphasizing the wide pulse pressure.  I see blood pressures ALL DAY.  It is not uncommon to have a pulse pressure of 80-90mmHg.  I would go as far as to say that is the norm that I see, rather than the "normal range of 40" that is academically proposed.  While it may be significant, in your eyes, i posit that it is not so much the singlular pulse pressure that matters, but the trend.  (This is of course excluding a very NARROW pulse pressure, which suggests some of our more serious pathological conditions.)  Interested in the continued discussion!


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## rhan101277 (Feb 26, 2010)

Even though this has nothing to do with the scenario I posted.  Isn't it possible to have rales for left or right sided MI?  Especially if the inferior wall of the RV is affected or the anterior wall of the LV is affected.  Both to me would seem like fluid would back up in the lungs.


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## rhan101277 (Feb 26, 2010)

Here is another test question I got right.

A 12-lead ECG that reveals slight ST segment elevation; Q waves in leads II, III, and aVF; and ST elevation in V1 and V2 most indicate which of the following?

A. Acute inferior MI with septal involvement.
B. Old inferior MI with acute MI septally.
C.The patient has had a myocardial infarction in her inferior wall and is experiencing ischemia extending into the right ventricle.
D.The patient has had a myocardial infarction in her inferior wall and is experiencing ischemia extending into the posterior wall of LV.


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## MrBrown (Feb 26, 2010)

I am glad to see your Paramedic course includes 12 lead ECG and that someoody didn't choose the ten-week route although you may miss the company of those Houston Firefighters 

II, III and AVF would indicate inferior while V1 and V2 would be septal







A. Acute inferior MI with septal involvement.
*Possible*

B. Old inferior MI with acute MI septally.
*Doesn't old MI show up as ST depression?*

C.The patient has had a myocardial infarction in her inferior wall and is experiencing ischemia extending into the right ventricle.
*It's possible but without any sign of RV disfunction or V1-6R you can't be sure*

D.The patient has had a myocardial infarction in her inferior wall and is experiencing ischemia extending into the posterior wall of LV. 
*This would be my answer ... but w/o V7-9 we can't tell*


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## 8jimi8 (Feb 26, 2010)

rhan101277 said:


> Even though this has nothing to do with the scenario I posted.  Isn't it possible to have rales for left or right sided MI?  Especially if the inferior wall of the RV is affected or the anterior wall of the LV is affected.  Both to me would seem like fluid would back up in the lungs.



While the pt may have rales as a secondary pathophysiology, i must refer you to the flow of blood to through the heart.

the Left ventricle backs up to the lungs. 

the right ventricle backs up to the inferior and superior vena cavae.  You wouldnt hear rales from an inferior MI.


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## 8jimi8 (Feb 26, 2010)

MrBrown said:


> I am glad to see your Paramedic course includes 12 lead ECG and that someoody didn't choose the ten-week route although you may miss the company of those Houston Firefighters
> 
> II, III and AVF would indicate inferior while V1 and V2 would be septal
> 
> ...



An old MI shows up as a pathologic Q wave... possibly a reciprocal change reflecting ST elevation in another area of the heart.   There are several other pathologies, but i'm pretty sure not an old mi.


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## rhan101277 (Feb 26, 2010)

C was the correct answer on the previous question i posted.

V1 and V2 indicates septal involvement which gets its blood from the right coronary artery.  The RCA supplies blood to the back side of the septum.


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## Veneficus (Feb 26, 2010)

8jimi8 said:


> Vene can you go into a little more about your reasoning in emphasizing the wide pulse pressure.  I see blood pressures ALL DAY.  It is not uncommon to have a pulse pressure of 80-90mmHg.  I would go as far as to say that is the norm that I see, rather than the "normal range of 40" that is academically proposed.  While it may be significant, in your eyes, i posit that it is not so much the singlular pulse pressure that matters, but the trend.  (This is of course excluding a very NARROW pulse pressure, which suggests some of our more serious pathological conditions.)  Interested in the continued discussion!



It continues part of the pattern of an increased attempt at output that is still compensating in the scenario. (otherwise the pulse pressure would be narrow indicating late shock) That might lead you more towards the furosimide distractor.  

I pointed it out more for test taking than for medical significance. I have never seen a paramedic or RN listen for a new S3 heart sound either. (or any other one for that matter)

Here is another example of building a pattern from unrealistic findings:

A 3-year-old girl is brought to the emergency department 30
minutes after she tripped and fell. Physical examination shows
*blue sclera* and edema and tenderness over the right proximal
lower extremity. X-rays show a *fracture of the right femur*, as
well as *several fractures of varying ages *of the left clavicle,
right humerus, and right fibula. Which of the following is the
most likely diagnosis?
(A) Achondroplasia
(B) Ehlers-Danlos syndrome
(C) Hurler syndrome
(D) Marfan syndrome
*(E) Osteogenesis imperfecta*

While I am quite familiar with the "baby gram" x-ray study, who starts x-raying upper extremities in a 3 year old with edema and tenderness in the lower right proximal extremity? It simply reinforces the pattern.


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## rhan101277 (Feb 26, 2010)

Veneficus said:


> It continues part of the pattern of an increased attempt at output that is still compensating in the scenario. (otherwise the pulse pressure would be narrow indicating late shock) That might lead you more towards the furosimide distractor.
> 
> I pointed it out more for test taking than for medical significance. I have never seen a paramedic or RN listen for a new S3 heart sound either. (or any other one for that matter)
> 
> ...



Yeah I tried to answer some of the questions in the USMLE step 1, as a paramedic student, only a few of them i was getting correct.  I just know a drop in the bucket.


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