usmle123
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I'm a little bit confused about the diagnosis steps for pulmonary embolism-do arterial blood gas first or V/Q lung scan?
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| frank100
Forum Guru
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depends on the patient´s presentation:
inpatient: if the patient´s hystory sugests you a high risk if pulmnay embolism such as, DVT, prior PE, major ortopedic surgery...and presents to you with tachicardia, sudden onset of dyspnea, sudden pleuritic chest pain, etc...send a V/Q scan. if the v/q scan is undetermined, do an angiogram.
out patient: comes with signs and symptoms os PE, same: perform a v/q scan first.
the point is: clinical suspicion = v/q scan
non conclusive v/q scan= angiogram
gases: never diagnostic. they should give you a clear clinical history sugesting a PE before, and you use the arterial gases to determine where is the problem. not a diagnostic tool, just part of it
* arterial gases: you only do AG whe there is an emergency (part of the emergency COMBO), or when you suspect that something wrong is going on with the O2 exchange, and you need to know if it is because of the lung or the kidney: intoxications, trauma, etc...
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| usmle123
Forum Senior
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frank100, it helps and thanks a lot. another question, do you know the difference between "CT angiogram" and "pulmonary angiography"?
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| Morphine
Forum Newbie
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But usmle world has a question which says in the explanation that do a chest xray and blood gases first and then go for v/q scan.
Im pretty confused
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| frank100
Forum Guru
Topics: 48
Posts: 586
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and you´re right morphine. but what I´m trying to say is that even when thr blood gases are normal and the CxR is normal, and you suspect PE. those are the best next steps.
It is difficult to create some kind of rule to that, because it depends on the presentation.
the best next step depends on what happened before..e.g: you have a patient postpartum day # 8, with a (+) homans sign who presents with recent onset of pleuritic chest pain. then you perfom labs and AG are ok, AND CxR is ok, your best next step is the same as if ABG´s and CxR where altered. you do CxR and ABG´s to elaborate a differential diagnosis.
depend on time too, because ABG´S tend to be ready STAT (if you wich), but fo CxR you need time.
so: THE BEST NEXT STEP is not always the same, depends of which part of the situation they ask you that. I f they say that the patien got into the hospital and with pleuritic chest pain and the whole presentation point towards PE, yes: next step is ABG, CxR, ETC...then...
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| AAAAA
Forum Fanatic
Topics: 156
Posts: 1,991
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frank100 wrote:
and you´re right morphine. but what I´m trying to say is that even when thr blood gases are normal and the CxR is normal, and you suspect PE. those are the best next steps.
It is difficult to create some kind of rule to that, because it depends on the presentation.
the best next step depends on what happened before..e.g: you have a patient postpartum day # 8, with a (+) homans sign who presents with recent onset of pleuritic chest pain. then you perfom labs and AG are ok, AND CxR is ok, your best next step is the same as if ABG´s and CxR where altered. you do CxR and ABG´s to elaborate a differential diagnosis.
depend on time too, because ABG´S tend to be ready STAT (if you wich), but fo CxR you need time.
so: THE BEST NEXT STEP is not always the same, depends of which part of the situation they ask you that. I f they say that the patien got into the hospital and with pleuritic chest pain and the whole presentation point towards PE, yes: next step is ABG, CxR, ETC...then...
It is absolutely not confusing.
Think, think,
A V/Q scan requires what?
A V/Q scan requires a whole more than ABG, 1,000 times more effort to do, need a technician, a nuclear medicine specialist, a $250,000.00 machine, 1 hour, and more..................
So the answer is do the simple things first.
ABG.
ABG is just a baseline test to compare longitudinally down the road if the patient improves. And by no means to prove or make the diagnosis of PE !
Common sense goes a long way !
But you only have 45 seconds to think in exam.
Used common sense. V/Q scan costs over $600.00.
ABG $30.00 !
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| AAAAA
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Morphine wrote:
But usmle world has a question which says in the explanation that do a chest xray and blood gases first and then go for v/q scan.
Im pretty confused
Never go for V/Q, do all the basic, CBC, lytes, ABG, D-dimer, CXR and then based on PE , and do V/Q only if highly suspicious !
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| mazinger
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interesting approach
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| AAAAA
Forum Fanatic
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mazinger wrote:
interesting approach
If the pre-test probability is very high, then do the V/Q after all the baseline tests.
What interesting approach ! I did ER for 30 years , 30 years, you can not do V/Q until all the baseline work-up is done !
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| mazinger
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AAAAA wrote:
What interesting approach ! I did ER for 30 years!
Dear AAAA there's no place for your selfcentered, obnoxious comments here..
This is just an open discussion for people who want to help, you dont have to be rude...
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| chiruSMLE
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i have been watching this fellow. HE gives long and Numerous explantions in many questions. And always uses words like think think as if he is the only person in the world who is thinking. and he is a kind of highly self centeed person. Seems like he has a narcistic personality disorder.
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| hussain_lashari
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very true chiru
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| AAAAA
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chiruSMLE wrote:
i have been watching this fellow. HE gives long and Numerous explantions in many questions. And always uses words like think think as if he is the only person in the world who is thinking. and he is a kind of highly self centeed person. Seems like he has a narcistic personality disorder.
First of all, I like to share with you what happened in the ER.
The guy came in and ordered an ultrasound on a 78 years old patient with nausea and vomiting. (Gallbladder ultrasound on Friday night).
He then left the ER and another ER doc came in and she reviewed the chart and cancelled the ultrasound and wrote a prescription of PPI and discharged the patient.
There are many different approach and the most important thing is to get a good history and physical before you ordered any expensive test.
It is not about me but a general concept of USMLE how to answer the question in real world.
The USMLE prepares you into the real world. Can you order a V/Q scan on Friday night? Well, it takes more than sitting behind the computer and argue about this but with 30 years experience, you understand what govern medicine is mroe than Harrison's principals, but money !
In order to have a V/Q scan, the Hospital Administrator has to make a call schedule 365 days a year for the nuclear medicine technician to be on call. Who is going to pay for the on-call, is the rate going to go up when she comes in. Since we have teleradiology imaging and also Mayo and many other institutions accept 24 hours consultation over the internet, it still takes sometimes 5 hours to interpret the V/Q scan.
It does not take 30 years, but need real clinical experience, residency in major and small rural hospitals to understand the logistics of medicine.
You are studying behind the computer but 'NO ONE, NO ONE WILL TELL YOU THE LOGISTICS OF DELIVERING MEDICINE.
So experience is very important on top of book work !
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| AAAAA
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hussain_lashari wrote:
very true chiru
Anyone who has no post is a ghost in this Forum ! (can make up a name and very true, hussain !)
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| hussain_lashari
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u mean if someone is silent watcher they even can not protest ???AAAAA i kno u have good knowledge but ur way is not good here and im watching u from long time i was thinking its just me who thinks that u r rude and as chiru said narcistic kind but every one noticed here so plz change ur behavior
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