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    (Original post by malaz_197)
    i did not come to medical school to learn about statistics and probability! if i see the words sensitivity and specificity again, i will do something irrational!
    I used to think that, but during A&E I recognised that understanding the limits of the investigations that guide your management is vital. If you are going to use a test result to make a decision to treat (say, DDimer in ?DVT) you have to understand the risk and implications of misleading results.
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    (Original post by Renal)
    I used to think that, but during A&E I recognised that understanding the limits of the investigations that guide your management is vital. If you are going to use a test result to make a decision to treat (say, DDimer in ?DVT) you have to understand the risk and implications of misleading results.
    hmm... i can see them being used in a GP setting. but surely, in terms of practicality, you wouldnt go and read up papers before treating someone with a ?DVT, right? unless you knew the values on top of your head of course.
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    (Original post by malaz_197)
    hmm... i can see them being used in a GP setting. but surely, in terms of practicality, you wouldnt go and read up papers before treating someone with a ?DVT, right? unless you knew the values on top of your head of course.
    It's not necessarily about reading papers - you have to know about the sensitivity and specificity of a test in order to correctly interpret the results.
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    (Original post by malaz_197)
    hmm... i can see them being used in a GP setting. but surely, in terms of practicality, you wouldnt go and read up papers before treating someone with a ?DVT, right? unless you knew the values on top of your head of course.
    This is what medical school's for though, right? Learning the basics of which tests are good to use and which aren't, and why.
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    (Original post by malaz_197)
    hmm... i can see them being used in a GP setting. but surely, in terms of practicality, you wouldnt go and read up papers before treating someone with a ?DVT, right? unless you knew the values on top of your head of course.
    There's certainly an expectation that you know which investigations are accurate and which aren't even if you don't know the numbers.

    For example;
    Rugby player hit in chest, c/o L rib pain, chest clear, RR & SpO2 good. Do you XRay for ?#ribs?
    Unwell elderly patient has an blood gas which shows a K+ of 5.8. Do you treat? What if it's 6.2? Do you wait for the U&Es result?
    Unrestrained driver, multiple trauma, c/o abdo pain. FAST scan is negative. What does that mean?
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    (Original post by Renal)
    There's certainly an expectation that you know which investigations are accurate and which aren't even if you don't know the numbers.

    For example;
    Rugby player hit in chest, c/o L rib pain, chest clear, RR & SpO2 good. Do you XRay for ?#ribs? No. Won't treat #ribs unless there's multiple ones, and if RR and sp02 are fine then likely no damage.
    Unwell elderly patient has an blood gas which shows a K+ of 5.8. Do you treat? What if it's 6.2? Do you wait for the U&Es result? Would want to know symptoms. How likely is it that the sample haemolysed on the way to the ABG machine? If it were >6, would treat if symptoms appeared to match suspicions. Else would wait for U&E.
    Unrestrained driver, multiple trauma, c/o abdo pain. FAST scan is negative. What does that mean? FAST neg = apparently no blood or fluid 'loose' in the abdomen, so likely no serious trauma like splenic rupture. However doesn't rule out organ laceration and bleeding cos ultrasound isn't that sensitive.
    I'm probably talking out my arse.
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    (Original post by Renal)
    There's certainly an expectation that you know which investigations are accurate and which aren't even if you don't know the numbers.

    For example;
    Rugby player hit in chest, c/o L rib pain, chest clear, RR & SpO2 good. Do you XRay for ?#ribs?
    Unwell elderly patient has an blood gas which shows a K+ of 5.8. Do you treat? What if it's 6.2? Do you wait for the U&Es result?
    Unrestrained driver, multiple trauma, c/o abdo pain. FAST scan is negative. What does that mean?
    Guessing
    1 - if no flail chest, and just tenderness on palpation, sats and resps holding up, pain control and send home. Even if there is a break, theres not much that can be done.
    2- consider drugs, is pt on drugs where k+ matters - digoxin. is pt cardio compromised? ?AF? Maybe stablise heart with Calcium gluconate to buy time. K+ effects kick in at around 6.5/7ish, so not panic, but monitored bed and prepare dextrose+fast insulin.
    3 - FAST is ultrasound for signs of trauma. Nil FAST dosn't necesssarily mean ok, because fluid capacitance of the abdomen means 1.5/2 ls needed before reliable detection, also ultrasound won't necessarily pick up tissue damage. errect CXR if possible to hunt for bowl perforations, also serum amylase. Otherwise CT chest abdo pelvis. ?Consider pericardiocentisis, surg reg r/w incase of theatre.
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    (Original post by Becca-Sarah)
    I'm probably talking out my arse.
    (Original post by Wangers)
    Guessing
    1 - if no flail chest, and just tenderness on palpation, sats and resps holding up, pain control and send home. Even if there is a break, theres not much that can be done.
    2- consider drugs, is pt on drugs where k+ matters - digoxin. is pt cardio compromised? ?AF? Maybe stablise heart with Calcium gluconate to buy time. K+ effects kick in at around 6.5/7ish, so not panic, but monitored bed and prepare dextrose+fast insulin.
    3 - FAST is ultrasound for signs of trauma. Nil FAST dosn't necesssarily mean ok, because fluid capacitance of the abdomen means 1.5/2 ls needed before reliable detection, also ultrasound won't necessarily pick up tissue damage. errect CXR if possible to hunt for bowl perforations, also serum amylase. Otherwise CT chest abdo pelvis. ?Consider pericardiocentisis, surg reg r/w incase of theatre.
    Guys, the point I'm trying to make is not about management per se but limitations of various investigations.

    1. Chest XRs do not reveal broken ribs unless there's real significant displacement, regardless of whether we'll treat or not.
    2. Blood gas measurement of electrolytes is notoriously inaccurate and can be up to +/-0.5 from the 'real' value.
    3. Simply, FAST is strictly rule in only. Therefore a negative FAST means nothing.
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    (Original post by Renal)
    Guys, the point I'm trying to make is not about management per se but limitations of various investigations.

    1. Chest XRs do not reveal broken ribs unless there's real significant displacement, regardless of whether we'll treat or not.
    2. Blood gas measurement of electrolytes is notoriously inaccurate and can be up to +/-0.5 from the 'real' value.
    3. Simply, FAST is strictly rule in only. Therefore a negative FAST means nothing.
    Point taken, out of curiosity, what about the management though . Ultimatly tests inform management...
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    I knew the CXR one...
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    (Original post by Renal)
    Guys, the point I'm trying to make is not about management per se but limitations of various investigations.

    1. Chest XRs do not reveal broken ribs unless there's real significant displacement, regardless of whether we'll treat or not.
    2. Blood gas measurement of electrolytes is notoriously inaccurate and can be up to +/-0.5 from the 'real' value.
    3. Simply, FAST is strictly rule in only. Therefore a negative FAST means nothing.
    Fair enough, I was using it as a mini quiz for revision purposes :tongue:

    Surely CXR is the same as any other x-ray for looking at fractures - if there's a break in the cortex you can see it, unless we're talking right round the back, in which case get a side-on view? I thought with PACS and the ability to adjust contrast etc on screen rib fractures would be visible...
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    Oh so like the D-Dimer test.

    See even I know some shiz
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    (Original post by Becca-Sarah)
    Fair enough, I was using it as a mini quiz for revision purposes :tongue:

    Surely CXR is the same as any other x-ray for looking at fractures - if there's a break in the cortex you can see it, unless we're talking right round the back, in which case get a side-on view? I thought with PACS and the ability to adjust contrast etc on screen rib fractures would be visible...

    There are some fractures that are notoriously hard to find even with all the tricks, hairline fractures - scaphoid for example is a classic clinical diagnosis. Yes, you can look for padding, and smoothness and stuff, but meh.
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    (Original post by Wangers)
    There are some fractures that are notoriously hard to find even with all the tricks, hairline fractures - scaphoid for example is a classic clinical diagnosis. Yes, you can look for padding, and smoothness and stuff, but meh.
    Scaphoid is a fairly obvious clinical diagnosis though. Pain on ASB compression/thumb telescoping = have a splint, come back in 2/52. I'm confused about why we x-ray twice tho (I get the whole delayed # presentation on x-ray bit) - 1st x-ray: displaced # -> deal with it. Undisplaced # -> splint. ?# -> splint. If you get a second x-ray in two weeks, for the ?#, what are you really going to change about your management? They've been in a splint for 2/52 already, why not just assume all clinical # is a real # and keep them all in splint for 6/52? What can you actually do if the end necroses anyway? I'm just confused because I've had a true # on one side and a ? on the other which turned out to be fine, and had exactly the same for both of them - x-ray, x-ray, MRI at 2 week intervals. That pretty much takes you to 6 weeks by which it's largely healing anyway... :confused:
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    (Original post by Wangers)
    Point taken, out of curiosity, what about the management though . Ultimatly tests inform management...
    (Original post by Becca-Sarah)
    Surely CXR is the same as any other x-ray for looking at fractures - if there's a break in the cortex you can see it, unless we're talking right round the back, in which case get a side-on view? I thought with PACS and the ability to adjust contrast etc on screen rib fractures would be visible...
    1. You don't XR for ?rib # unless there is suspicion of a complication e.g. pneumothorax, flail segment etc. The advent of PACS has certainly made it easier to see them in funny places, but they are still tricky, especially low down anteriorly and laterally as there's so much soft tissue in the way. And lots of departments for some bizarre reason will not do lateral chest films. An uncomplicated rib fracture gets exactly the same treatment as soft tissue injury so there is no point in imaging just for that.
    2. Depends on just how unwell the patient is, anything else you know about them and if they have any ECG changes. Ordinarily it would not be wise to treat a K+ of 5.8 based on a gas result alone, so you need a bigger picture. Calcium gluconate is not a simple thing to give - you need cardiac monitoring and in many places it needs to be given by a doctor so it's not just a matter of a quick fix to buy time.
    3. If they still have abdominal signs, then if they are well enough it's time for a trip to the Doughnut of Death.
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    im convinced they are important to have a general idea of as a clinician. sometimes it seems as though there is no answer and the implication on management depends on the clinician's judgement. for example the x-ray dude, if we think its inconclusive, someone could send home and someone else could ask for a CT (or whatever the next approriate test is). anyway, i just have a case analysis project which asks you to quote specific numbers, inc. reference ranges, that relate to the patient's case and im having trouble finding them so i wanted to rant
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    (Original post by Helenia)
    Thanks for explaining those - really useful! Doughnut of Death... LOL :rolleyes:
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    (Original post by Becca-Sarah)
    Scaphoid is a fairly obvious clinical diagnosis though. Pain on ASB compression/thumb telescoping = have a splint, come back in 2/52. I'm confused about why we x-ray twice tho (I get the whole delayed # presentation on x-ray bit) - 1st x-ray: displaced # -> deal with it. Undisplaced # -> splint. ?# -> splint. If you get a second x-ray in two weeks, for the ?#, what are you really going to change about your management? They've been in a splint for 2/52 already, why not just assume all clinical # is a real # and keep them all in splint for 6/52? What can you actually do if the end necroses anyway? I'm just confused because I've had a true # on one side and a ? on the other which turned out to be fine, and had exactly the same for both of them - x-ray, x-ray, MRI at 2 week intervals. That pretty much takes you to 6 weeks by which it's largely healing anyway... :confused:
    I'm not sure, because I'm not quite as keen on orthopaedics as you (:p: ) but my guess would be that management after two weeks would depend on both the x-ray and the clinical picture. If someone had completely recovered, had no pain/tenderness and a good range of movement at two weeks, alongside a normal 2nd x-ray, then my feeling is it wouldn't be unreasonable to take the splint off and see how it goes, thus saving the patient 4 weeks in a splint and the NHS several hundred £ for an MRI. If they still have any symptoms/signs at that stage then I agree I'm not sure what the 2nd x-ray would change and that MRI is what's really needed.
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    (Original post by malaz_197)
    im convinced they are important to have a general idea of as a clinician. sometimes it seems as though there is no answer and the implication on management depends on the clinician's judgement. for example the x-ray dude, if we think its inconclusive, someone could send home and someone else could ask for a CT (or whatever the next approriate test is). anyway, i just have a case analysis project which asks you to quote specific numbers, inc. reference ranges, that relate to the patient's case and im having trouble finding them so i wanted to rant
    Good luck - it'll vary by laboratory.
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    (Original post by malaz_197)
    im convinced they are important to have a general idea of as a clinician. sometimes it seems as though there is no answer and the implication on management depends on the clinician's judgement. for example the x-ray dude, if we think its inconclusive, someone could send home and someone else could ask for a CT (or whatever the next approriate test is). anyway, i just have a case analysis project which asks you to quote specific numbers, inc. reference ranges, that relate to the patient's case and im having trouble finding them so i wanted to rant
    Does this help at all? :dontknow:
 
 
 
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