chbare

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chbare last won the day on December 18 2016

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  1. chbare

    Pathophysiology of cyanide poisioning

    Hi Kenny, the chief way cyanide antidotes work is not really centered around directly acting on cytochrome c oxidase, but rather haemoglobin; at least in the case of the traditional therapy (Nitrates + Methylene Blue). As I outlined in the video, the traditional therapy changes the oxidation state of the Iron atom in the porphyrin ring of the sub units of haemoglobin. Typically, the Iron will be in a default configuration of +2/Fe II/Ferrous. Nitrates and other substances can further oxidise the Iron into the +3/FeIII/Ferric state. For reasons that I cannot pull out of my head (I suspect it has to do with the fact that Fe III is a strong Lewis acid and would not be able to coordinate reversibly with the Oxygen molecule.) Fe III does not coordinate with the Oxygen molecule. It however does coordinate exceptionally well with cyanide. This will create a situation where kinetics and thermodynamics favour cyanide coordination with the haemoglobin as opposed to the Iron in the cytochrome c oxidase enzyme. However, this also means the patient has methaemoblobin toxicity and could develop histotoxic hypoxia due to ineffective haemoglobin function. Hence, the need to administer agents that can reduce haemoglobin such as methylene blue. However, the other antidote modality in the United States works very differently. Hydroxocobalamin is a vitamin B12 precursor that contains a Cobalt atom configured in a way that allows it to have a high affinity for the cyanide molecule. The high affinity favours the coordination of cyanide with the Cobalt as opposed to the Iron in cytochrome c oxidase. Again, the exact details are complex, but chemical kinetics and thermodynamics favour Cobalt coordination in this case. A relatively inert molecule known as cyanocobalamin is produced in a 1:1 manner (1 mole of hydroxocobalamin can coordinate with 1 mole of cyanide) that is easily eliminated in the urine. Hopefully that helps out a bit. No worries about being a student. Do not let anybody make you think humanity has developed a deep understand of these things. Much of the universe is a complete mystery to us and as you progress along your educational pathway, you will likely be disturbed from how inadequate and uncertain you feel at each step along the process. My experience has been that with every degree that I have obtained, I had the expectation that I would emerge with a more comprehensive understanding of the world. Every step left me lacking significantly. This was not due to lack of trying or failure of dedication, but a fundamental part of the uncertainty of being a human being attempting to understand a vast and complex universe. Point being, I do not want you to be discouraged.
  2. chbare

    Pathophysiology of cyanide poisioning

    Good day. You are a bit off but the general reasoning in the the right direction. I will post a video that I filmed some years ago while I was in graduate school. It covers this topic, but I'd ask that you review the concepts of ferrous versus ferric Iron and ultimately, the concept of oxidation state. The Iron in Cytochrome c oxidase is in a similar configuration as haemoglobin but the enzyme dynamics dictate a narrative that is counter to the typical "blood poisoning" that sometimes surrounds a discussion of Cyanide Toxicity. I must warn you that I was grossly overweight and profoundly depressed when I made the video, so it's not super high fidelity, but the information is relevant nonetheless.
  3. chbare

    CHF & Low BP

    Dobutamine is a tricky one. Like some of the other sympathomimetics, it comes as a racemic mixture. One isomer has very mild alpha 1 agonist effects while the other isomer has mild alpha 1 antagonising effects. This means it may not reliably support blood pressure, even if it does enhance contractility. In an already hypotensive patient, dobutamine may be problematic without the concomitant use of agents that are better at supporting blood pressure.
  4. I thought it was worth it back in the day. Of course my motives were pretentious and derived from a "type-A personality" that wanted to be better than everyone else. When I left flying, my list of friends and colleagues was shorter and I had recurrent nightmares of crashing. To this day, I have anxiety when it comes to flying. Not sure if it was worth it in retrospect but I'm sure individual mileage will vary.
  5. chbare

    2015 ACLS updates

    Targeted temperature management in the ROSC patient is one of the bigger changes.
  6. chbare

    NS - going the way of MAST pants?

    I've read a couple of opinions and one can be referenced here: http://www.bmj.com/rapid-response/2011/11/01/hartmann’s-solution-and-09-saline-are-both-unsuitable-severe-dka Unfortunately, the author references many sources that do not specifically consider DKA. I will also refrain from a strong ion discussion but I'm not convinced that a SID approach is superior and clinically more useful than standard approaches. Ive seen modest studies that compare NS and LR in DKA patients. One such abstract can be referenced here: http://www.ncbi.nlm.nih.gov/m/pubmed/22109683/ I would love a reasonable evidence based approach but I'm not really compelled to say NS volume expansion in a prehospital setting involving DKA is harmful. I'm willing to change my mind however.
  7. chbare

    NS - going the way of MAST pants?

    Just to clarify, are you saying DKA patients should not routinely receive initial blouses of fluid?
  8. chbare

    Narcan at the EMT level.

    Again, I think it is important to emphasise a key point. ERdoc is not talking about "awaking" people up. I believe he and others are discussing this in terms of a much more nuanced approach. As already stated, anecdote is of limited value when attempting to generalise. Is there literature that looks at the issue at hand however?
  9. chbare

    Thoughts on this? Uber style Narcan delivery!

    First, we need to be able to divorce human hubris and bias from the discussion. For example, I saw earlier comments go on about heroin. What does the data tell us about the types of opioid overdoses that are killing folks? In many cases, the substances involved were not illegally pulled from poppy fields in Afghsnistan, but rather were from prescription opioids. Once we start attaching emotions and using bias to conflate the picture, it is easy to make incorrect conclusions that can further reinforce prior assertions that may not accurately reflect the actual situation. With that said, I would ask to look at the evidence. What is the impact when naloxone programmes are used? Do they lead to increased abuse and more problems as some may assert? In general, how does education and risk reduction compare to the use of coercion (making drugs illegal and throwing people in prison) when combating the issue of opioid associated death via overdose? There is a base of literature out there that could allow us to make reasonable conclusions. Regarding this particular article and novel approaches it suggests, I'd ask if it was worth considering the author's thesis based on the current literature. I'm not entirely sure, but would it be worthwhile for somebody to develop a protocol, approach an IRB and gather some data?
  10. chbare

    LGBT in EMS/Fire

    I have to disagree with "don't ask don't tell." The subjects of kids, home life, life partners, relationships and so on come up naturally as most humans are socially inclined animals. This is particularly true in an intimate setting such as EMS where you may spend 12 or more hours in close contact with another person or a small group of people. I simply cannot see how such subjects would not come up as a natural consequence of normal social activities. Unfortunately, in the United States, a whole bunch of people care. Going into elections, this is becoming an issue that potential candidates are already talking about on national and international multimedia. Additionally, the Supreme Court will be making a decision that will (hopefully) address the issue of equal treatment. Regardless of the decision, this country is markedly polarised on certain issues and to think that the issue will not be in the minds of EMS providers is probably rather myopic and naïve. Remember, as little as two decades ago, these issues were largely buried and not at all on the forefront of the cultural consciousness of the United States. Things have changed in a big way and the zeitgeist of our nation and perhaps the world may very well be changing and doing so on the scale of human lifetimes.
  11. chbare

    Endotracheal Intubation vs. King LT

    No, a Japanese study showed less favorable results in arrest patients who had advanced airways placed. Unfortunately, I believe some of the issues revolved around the fact that they used a variety of devices including EOA's? There was a very small animal study (n=9) that indicates SGA's may decrease CBF in the arresting animals.
  12. chbare

    Combat medics transition to paramedics

    Hi Ghost. I am saying this as a former 91B who reclassified to the newer MOS designation. I joined the military back in the 1990's and was in until the mid 2000's. I started as an E1 and worked my way into the NCO ranks/grade. While I never deployed OCONUS I did do a contract in Afghanistan a few years after I got out. Here's the issue; being a civilian paramedic isn't about providing trauma care in a non-permissive environment. Medical cases abound and the patient populations are incredibly diverse. Additionally, the trauma patterns tend to be more blunt in nature. You are dealing with complex chronic pathology, significant medical issues and a civilian operational environment. This is markedly different than what many 68W series guys get. Certain ASI's such as the M6 have significant civilian crossover however and the newer flight medic programme looks to provide NR-Paramedic credentials. So, as a soldier you potentially have other schools and options that you can choose from with better civilian crossover. However, as a soldier, you are there to serve Uncle Sugar and he's under no obligation to hand you a civilian credential that you may not fully understand but believe you deserve. I believe military medics have much to offer, but they will likely need to attend the proper training and education programmes to successfully make the civilian paramedic transition. Luckily, the military is usually pretty good at offering assistance to combat vets as they transition into the civilian workforce. Unfortunately, I fear you simply do not know what you do not know. Please attempt to look at the bigger picture and appreciate the fact that you may not have a fully developed appreciation of the role of the civilian paramedic.
  13. chbare

    Pain Management

    Oh, pain meds were given, but the patient was pretty messed up and giving more than 100 mcg of fentanyl will apparently result in a patient's head spinning around a couple of times, falling off, rolling down the hallway and spontaneously combusting in the Pyxis room.
  14. chbare

    Pain Management

    Man, just had a rough one in the ER. Older patient fell down and sustained multiple fractures. Screaming in pain, couldn't get orders. It sucks seeing people needlessly suffer. Rather happy my hospital shifts are limited by educational duties these days. It can be a pretty nihilistic environment as far as providers are concerned. Some days are a constant fight against people who just don't care or are really good at making up reasons not to care. Even worse not having any power to facilitate comfort. Don't take the autonomy you have to make more independant decisions out in the field lightly folks.
  15. chbare

    Pain Management

    [Citation needed].