D Assessment & DDx (Differential) of Consequence

00:01 Now, I mentioned before, this isn't just an ABC assessment, it’s an ABCD assessment.

00:07 And what does that D stand for? Two things: disability and dextrose.

00:12 So by disability, I mean, your neurologic exam or the patient’s underlying neurologic status.

00:18 And there's three things that we wanna check when we think about the patient’s neuro exam.

00:22 One is their pupil size and reactivity.

00:24 That’s gonna give us clues again about the potential underlying cause of their problem.

00:29 Two, is symmetry of extremity movement.

00:32 So basically, we want a quick assessment of whether the patient has neurologic focality.

00:37 If the patient's moving everything equally, well, that's a good sign that whatever is going on with them is not a focal CNS process, it's something more diffuse.

00:45 Whereas if they're unable to move just one extremity or from the waist down, we wanna think about the possibility of neurologic injury causing that situation.

00:55 And three, we wanna quantify their level of consciousness and we do that by measuring their Glasgow Coma Scale which we're gonna talk about in more detail in the future lecture.

01:05 Lastly, don’t forget your dextrose.

01:08 So you wanna check the glucose level on every single patient who has even a hint of altered mental status.

01:14 Remember, hypoglycemia is 100% reversible, it’s one of the few things in medicine we can always cure so we wanna make sure we check it and we don’t miss it in situations where it could be contributing to the patients pathology.

01:29 So we wanna ask the right questions at the right time, the first thing we ask, like we already said is, is this patient sick or are they not sick? The things that will tell us that they're sick, again, are unstable vital signs.

01:43 Any sign of airway compromise or significant respiratory distress.

01:48 Any sign of hypoperfusion including altered mental status, cyanosis, shock, etc., any non-sinus cardiac rhythm, altered mental status, or depressed sensorium, and anytime the patient just looks bad, right? If they're in extreme pain and any kind of subjective distress, take that seriously as a potential sign of illness.

02:11 Now, if they're not sick, we can feel a little bit more relaxed and maybe proceed with their evaluation in a more leisurely fashion, but if they are, we need to move ourselves on to asking the next critical question which is, what is this patient’s differential of consequence? Now, what do I mean by that concept? Very simply, the differential of consequence are the diseases in the overall differential diagnosis that represent an imminent threat to that patient’s life or health.

02:41 So these are the most dangerous diagnoses, not the most likely ones.

02:46 These are the things that we can’t afford to miss for any patient.

02:52 So in Emergency Medicine, we don’t necessarily care so much about identifying what the actual diagnosis is.

03:00 It’s a nice bonus when we can do that but what we really care about more is not missing something serious.

03:06 The thing we need to remember in Emergency Medicine is that every patient who comes to see us has left the comfort and safety of their home and come to the Emergency Department because they believe that they are acutely ill.

03:18 It's our job to prove that they're not.

03:23 Worst first, we’ve got to consider the bad things in the differential before we start worrying about the benign things in the differential.

03:32 So how do we develop our differential diagnosis? Well, just like all of medicine, it starts with the focused history.

03:38 But in the ED the question we wanna ask is, why are they here right now? We don’t wanna know about the big picture of their overall health, we wanna know what brought them in today and why today is different than yesterday, or the day before, or any other day they could have come in for this problem.

03:55 We wanna consider the patient’s past history but only the elements of that past history that help us understand the current presentation today.

04:04 We wanna know what potential organ systems could be implicated and we wanna do the right physical exam maneuvers for those organ systems and based on all of that, we wanna identify the pathophysiologic processes that might explain what we're finding, what's going on with the patient right now.

04:22 So our goal when we take a history and perform a physical exam is to test hypotheses.

04:30 We wanna formulate a set of hypotheses about what the underlying diagnosis is and every question that we ask, every exam manuever we perform, we should always be asking ourselves, does this support or refute my hypothesis? So every single thing we do is helping us either expand or narrow the differential diagnosis for our patient and ultimately make a clinical decision about what's going on with them.

04:58 So in order to explore the differential of consequence adequately, we wanna make sure that we learn basic approaches for working up common problems.

05:06 There are things you'll see in the ED over and over again.

05:08 Chest pain, abdominal pain, shortness of breath, headache.

05:11 We wanna think about what are the right questions to ask for those patients and what are the right exam maneuvers to do? What are the tests we wanna think about getting? And that's gonna be a lot of what we cover in future lectures in this course.

05:25 We wanna consider our overall history and physical findings and our ancillary test results in terms of what they might mean.

05:34 What the differential they're suggesting to us is.

05:38 And we wanna rule out any diagnoses that are incompatible with our findings.

05:42 So if I get a history that sounds absolutely nothing like cardiac chest pain, and I have a physical exam that’s totally normal, I can potentially take a cardiac etiology of my patient’s chest pain off the table, based on my history and physical.

05:57 But if I am still concerned about the possibility of a serious diagnosis based on my history and physical, I'm gonna get tests that are gonna help me rule in or rule out different diseases, and I wanna — before I interpret those tests I wanna know what the pretest probability for those diagnoses is.

06:17 And that’s very important coz that's gonna inform how I think about my test results.

06:22 So ancillary test should always be considered in light of pretest probability.

06:28 And the reason for this is that no test is perfect, right? So tests have false positives and false negatives and we need to be prepared to think about our tests results in terms of what they really mean.

06:41 For patients who have a very low probability of a given diagnoses, I might not need any test.

06:47 For a patient who has moderate probability, tests are great, right? If I'm really not sure, is this an MI? Is it not an MI? Well, then a test is gonna help me make that diagnosis.

06:58 And for very high probability of disease processes, tests again become a little bit less useful because if I really think I know what's going on clinical grounds, you know, I don’t necessarily need a test to advance my clinical reasoning in that setting.

07:13 But when I think about my test results, a negative result has a very different meaning for a high probability versus a low probability patient.

07:22 In a low probability patient, it probably really means that the disease is not present, whereas in a higher probability patient, I have to consider the possibility that it could be a false negative result.

07:33 And that I still need to perform further workup.

07:36 This is a really, really important concept in Emergency Medicine, because as doctors, so few things are black and white.

07:43 There are so few things that are a 100% in medicine.

07:46 We get really hang up on the idea that tests are the answer and that tests really tell us what is or isn’t going on.

07:53 But just like anything else in medicine, it's just a piece of data and it has to be interpreted in the broader context of the patient’s presentation.

08:02 So we wanna make sure that we're always thinking about our test results in terms of the pretest probability of a given result.