Hey Brandon, great discussion for sure!
I'm sorry but I fail to see the point in your post. You keep coming back to this idea of if it doesn't change your treatment it must be useless.
I don't know how else to explain to you what I consider the value of the knowledge in the pathophysiology. I don't believe that just because something isn't going to change my treatment it's useless. That's not how real differential diagnosis works.
You act like it's a simple matter to even be 100% sure in the field that you are dealing with COPD. Sure, 8 out of 10 times it is. 8 out of 10 patients are simple no matter what. But a small part of the time they aren't. I'm not arguing that differentiating between the two will necessarily change my treatment. These patients may be minor and I'm not going to treat them at all, but that doesn't mean it's not by job to diagnose them to the best of my ability.
Have you ever heard the term aim small miss small? Well, if I'm busy trying to figure out if my patient has Chronic Bronchitis or Emphysema, I'm not trying to figure out if they have COPD or CHF, asthma, pulmonary emboli, or something else. I feel like we are on the same page that the diseases are drastically different and your saying, sure but the presentation and clinical care are hopelessly intertwined so working with them together is simpler, and more effective. From a student point of view, or studying for the boards I get that. However I disagree that they can't be differentiated, or that it's not clinically valuable.
These are unarguably different diseases, caused by and sharing some factors. But the pathophysiology that in-between the cause and presentation, and the altered mechanics, and physics of gas exchange in the new environment are entirely different. The long term effects of the diseases are different on the body, and reactions to treatments are effected by the different changes in those dynamics in each disease. Here is one example about oxygen utilization but there are many studies. In a sample size of only 20 drastic physiologic differences were found: http://www.ncbi.nlm.nih.gov/pubmed/8520795
Thus, in emphysematous patients, the oxygen available for tissues other than respiratory muscles was significantly reduced (emphysema: 124 +/- 51 ml/min/m2; chronic bronchitis: 207 +/- 78 ml/min/m2; p < 0.02). This could explain nutritional differences observed between patients with emphysema and those with chronic bronchitis.
This is the kind of information that makes you a better clinician. You have to practice science based medicine rather than evidence based medicine. The above study shows me that in emphysema patients it's likely that we are dealing with an entirely different physiologic oxygen delivery situation than chronic bronchitis patients. This affects every decision I make from O2 management, to how quickly I will consider bicarb in a prolonged resuscitation. Information like that makes me think more about affecting the offload affinity of oxygen in an emphysema patient and the on-load affinity of oxygen in a bronchitis patient. Does it make a difference? I don't know it would be impossible to gather data on such a specific subset of patients in a meaningful way, for me at least, but I do know that calling all those patients COPD and treating them the same means that those few that would benefit from tailored care don't get it. We are taught that evidence is the most important thing, it's not. Evidenced based medicine is giving way to science based medicine, where we understand that because data collection isn't perfect and ubiquitous we should use evidence to inform scientific theory and base practice on that. I'm not changing treatment protocols, I'm changing how I utilize them based on the specific patient.
This doesn't even touch on the idea of concurrent pathology that muddies the waters. These patients often have confounding and unrelated physiologic process going on. A more complete understanding of the different pathophysiologies under the umbrella "COPD", in my opinon, can ONLY lead to better clinical care. I don't think you are arguing that they aren't different, we just have different outlooks on what that means. If someone has advanced CHF, Emphysima, PNE and Diabetes related pathology, looking for COPD among significant amounts of signs and symptoms from those diseases is difficult, looking for something more specific will help you determine what S/S are being caused by what process.
I spent the last five years or so working in critical care and flight medicine so, my perspective isn't of a textbook stand alone COPD patient. In that case, you're right, I doubt any of this knowledge would come in handy. But I really don't care about a standalone COPD patient, I can care for that person without significant thought. It's the one out of ten, one out of a hundred, patients that this sort of specialized knowledge comes into play. If it were up to me we would teach Paramedics the specifics of A-type, B-type and centrilobular and panlobular emphysema.
That being said it is my opinion that we are going to continue to see how different these diseases are and, as we removed asthma from the spectrum we will realize that other than initial causes and overlapping S/S the two have little to do with each other, but are often concurrently present. One study in Feb. 2013 in .... (Chronic Bronchitis and COPD)found that:
"It is known now that many patients with severe emphysema can develop CB, and small airway pathology has been linked to worse clinical outcomes..."
and goes on to state:
"However, in recent years, a greater understanding of the importance of CB as a phenotype to identify patients with a beneficial response to therapy has been described"
That's far from the only place making progress on this, but I've never hear anyone argue that they are prognostic-ally the same. Since that's your statement it falls on you to provide proof that they are. Just because we reported COPD statistics together for a long time doesn't mean that the morbidity and mortality is the same for everything in that category, just that we averaged them all together.
All THAT being said. It doesn't matter. If you really are an EMT and you have the level of knowledge to engage in this conversation, you're fine, I'm fine, we're giving better medical care with a deeper understanding of these things than most practicing emergency physicians could still remember from school. These are the kinds of disagreements that I'm totally ok with having because I know you understand this better than 99% of people out there. We're really just arguing semantics, who cares what we call it.
Why?
