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I'm going to start with some very high level general principles and then look at some specific areas of practice. The main focus will be on the first few days or a couple of weeks after injury and particularly focusing on ballistic and blast injury. But we will briefly mention burns. One of the first principles is that every theater war will have different challenges. The first of which, depending on the nature of engagement with the enemy, the nature of military engagement, you may see different injury patterns. The next principle is that wherever you are in the world, there will always be a local anti microbial resistance pattern but may pose considerable challenges to you in the choice of antibiotics that you can use. The next principle is that deployed forces may be exposed to local environmental pathogens either from the physical environment or because of exposure to animals, insects or other other life forms, but will transmit diseases. And this also links into the idea of local endemic infectious diseases that are present in the population or in a particular area. And even as trauma surgeons, you will have to remember the whole patient that they may have been exposed to an infectious disease, malaria, tuberculosis, um tick Boylan Katha litis that may cause you some difficulty in thinking about a fever or infection in the post trawler phase of your care. And of course, some of these infections will pose a risk to other patient's because of onward transmission or even the healthcare workers. And so here's the first example where working as a team with colleagues with other expertise is a really important principle of managing the injured military or civilian casualty in an area of conflict. So the next principles are the battlefield injuries are always contaminated and that prompts surgical management is really really important. Oh, you will be, I'm sure familiar with the concept of damage control surgery and that it's really important to debride any dead tissue and remove contamination um important from a surgical perspective, but also important from managing infection. And the final principal in the surgical perspective is that these battlefield wounds most will require would read look that is because the zone of demarcation of injury may not become apparent till up to three days because the sheer forces and the microvascular damage that you will see in last and ballistic injury is not apparent at day one. When you first see your patient Diko, might you like to add anything to that from your perspective as a surgeon having seen these injuries in the early phase? Well, I think that's absolutely correct. The key is to divide as much as, as necessary and particularly in blast injuries where multiple tissue planes are involved. It's very important to be meticulous in your divide mint and to remove dead or necrotic tissue because the obviously form the basis of any infection. And as you've mentioned, initially, the full extent of the damage may not be apparent. So it's important not to just do one divide mint, but to do repeated department until you get to the stage where your wound is clean and ready for reconstruction. That said we have to recognize that sometimes you cannot fully divide because you are limited by the physiology of the patient. And sometimes you just have to accept that you go back 24 hours later, when the intensive care, colleagues have managed to stabilize physiology a little more and we live with our organic burden within the patient. We will revisit this theme later. When you think about some specific infections. Finally, we should remember what antibiotics should be given early. They are not a substitute for surgery, they go hand in hand. So they should be clear. But antibiotic prophylaxis given early as near to the point of injury is different from pre emptive therapy when you know you are going to get infection. And we'll think about some examples of that and treatment when you already have infection of very different concepts. So, antimicrobial stewardship by which I mean, using antibiotics very wisely as limited as possible. So right, antibiotic, right. Patient, right length of time is really important for the individual patient, but also for the population of patient and infection control within the healthcare setting is also really important to stop the spread of organisms and to stop the increase in resistance to antibiotics. And we also know that the evacuation chain moving patient's from the point of injury through the healthcare system to a place of final management also increases antibiotic resistance. We saw this plenty of times with our military experience through countries that we're not at war. If you're trying to move patient's within a war zone, the problems are even worse. So the final point on this principle is that the question we should ask ourselves is are the antibiotics going to make a difference to the outcome rather than are they're micro organisms present. Um So we have to differentiate colonization from active infection men broader principles. But the multidisciplinary team um really supports better outcomes. Um Having people like me to respect for the challenge deeper and her colleagues, our surgeons to really make them think about the antibiotics, how they're using it to bring the laboratory expertise and interpretation and also how to investigate for infection has really, really helped in how we work and contributed to the outcomes we had with our military casualties deeper. I'm sure you could answer that. I completely agree. I think that when we treat these very challenging injuries, uh we're trying to treat the patient as a whole, not just the injury, but we find that if we make all those other things better, just as you've mentioned, not just the surgery, but what we're aiming for is to get the injury to heal and to get the injury to heal, you don't just need surgery, you need all those other principles like microbiology, like um nutrition like analgesia, physiotherapy. So each of those things combined has a role to play in making the patient better. One of the examples that, that we found that was really, really important with our military patient was focusing on nutrition. We all know what the baseline requirements are in the normal person. But if you take in our context, very fit muscular young men, they do not have a calorie requirement. 2.5 1000 calories a day. It's much more, they are very cata bolic from their injury. So we had to pay really attention to getting their nutrition right? And without any disrespect to my surgical colleagues, there's a lot more to focusing on the bone. Speaker said there's the whole patient and our rehabilitation colleagues are physiotherapists, occupational therapist were very helpful. Pointing out yes. But if you do that, what about the fact that they can't move their arm if you're expecting them to mobilize on that leg. So thinking as a team about how to get the whole patient healed and moving again is really important. It is important in military trauma, battlefield injury as it is in civilian COVID trauma. So we turn nail to some sort of more practical things about the individual patient. So from a surgical perspective, you will be familiar with thinking about the mechanism of injury, informing the known and obvious injury, but what might also be wrong with the patient but will predict your surgical management. But when I think about assessing the mechanism of injury as an infection practitioner, I'm thinking about the breaches of normal anatomical barriers that might predispose to infection such as penetrating abdominal trauma that involves the gastrointestinal tract. So the importance of thinking about what anatomy has been damaged is there are occasions when it might influence the choice of um prophylactic antibiotics. So gastrointestinal perforation will need some grand negative cover that you might not normally use in trauma. And also thinking about tissue penetration of antibiotics. And there are some occasions when specific tissues will need a different choice of antibiotics. So, penetrating injury to the eye because it's very difficult for some antibiotics to penetrate the eye or into the brain will require different choices. The next point again, thinking it from my perspective as an infection specialist is understanding the environment of the injury. So for example, whether the patient was injured where there was surface water that might have been contaminated because of the range of microorganisms that might be there. And I don't expect trauma practitioners to know about those microorganisms. You're very, very good at putting patient's back together is my role to know about those microorganisms. And here's a really good example of how we work together as a team. So if we think about a patient moving from the point of injury to one healthcare facility to the next, it's important that we document details like that because the patient may not be able to tell us deeper. Would you like to add anything to those principles? No, I completely agree with all of them. So, if we're thinking about prevention of infection, um we need to give antibiotics as soon as possible, but we need to limit those targets to the grand positive organisms. Particularly staph aureus beat a Hema is extract a cocky and in the context of battlefield injury, in particular clostridia. Although the same applies to civilian trauma. The next thing we need to do as early as possible is thoroughly debride wound, to remove or any dead or devitalized tissue and to clean out any contamination. But there will be a tension here between how much tissue to remove without wishing to compromise subsequent reconstruction. And I will invite deeper to comment on that because this is a surgical principle. Uh So that's right. I think uh there's often uh tension between actually usually between the bribe mint and what the patient is able to tolerate physiologically. Um Often these patient's are quite sick and uh you have to balance the patient's physiology with the amount of debridement that you do. So, uh we, we found uh when we were looking after these injuries that it's better to do as much as you can. But we, we ask to be at least a test to tell us how long we can go on for. And if they say you only have 20 minutes or 30 minutes, then you do what you can in that time and then you come back later on because you've given the patient a chance to stabilize when it comes to the tension between debriding and reconstructing, uh we would debride whatever we need to. So because we are fortunate to work in a multidisciplinary team which involves orthopedic and plastic surgeons. Uh We're not worried about being radical in our debridement. Uh Because we know that we have the skills to mostly reconstruct tissue that has been lost, whether it's bone or soft tissue. The, the only exception to that would be articular surface. The next point is about fracture stabilization. It needs, it needs to be done early. But you need to temporize. My understanding is you should never do an internal fixation unless you've got the course too robust soft tissue infection. Yes, that's right. So, uh stabilization of long bone fractures in particular is really important in order to maintain the patient's physiological balance because we know that if we leave fractures unstable, then it affects the patient's physiology. So we try to stabilize as early as possible, but we don't use in terms of fixation unless we have a good soft tissue cover. The next point is about when to close the wound. Yeah, battlefield injuries are always contaminated and you should always be using a principle of delayed primary closure. But that doesn't mean but a simple through and through gunshot wound that's been adequately debrided or flossed may be able to close that here is a really good opportunity to think about a wound that's been debrided and is clean is probably somewhere where you should be stopping antibiotics sooner rather than later. And in contrast, if we think about a bigger ballistic injury, it will be colonized. But if it's been adequately surgical debrided, and if you've got a good dressing or TNP, topical negative pressure dressing, it's here. We can ask the question about whether antibiotics going to make a difference. Speaker, I'm sure you have words of wisdom. Uh Not particularly, I, I agree that all the principles that you've mentioned so far, I guess the only thing I would add is that we haven't found there to be any benefit in uh when we do our cleaning, we haven't found there to be any benefit in using topical antiseptic solutions or antibiotics. We clean only with Saline which leads us on to after surgery. What dressing a simple goals, dressing is fine or topical negative pressure. And the advantage of TMP is that it allows you to manage wound exudate much more adequately. Uh huh. Uh, yeah, absolutely. So, if you, there's no real advantage between the two, but if you use simple dressings, then they tend to soak through. And that means that you have to keep changing the dressings and for patient's who have large wounds or who need an anesthetic in order to do a dressing change, that's quite labor intensive and not necessarily a good thing for the patient to be having an anesthetic every day just to reemphasize. But even with a simple dressing, the big wound or using topical negative pressure dressing, neither of those are an indication itself to continue antibiotics or is an indication signs of infection. And finally, we need to think about our role as healthcare practitioners in preventing infection, not just in the patient in front of us, but our role in spreading it to other patient's. So hand washing, good hygiene practice, looking after intravascular devices properly, particular is something that we have a huge responsibility. Just a few quick thoughts about burns and to draw the distinction from civilian practice. So in civilian practice, we would normally excise the burn very quickly and we would not give antibiotic prophylaxis. But in battlefield burns, we would give antibiotic, prophylaxis and use the same approach as in trauma. And here there is some evidence that using an antimicrobial dressing, a silver containing dressing uh does have a role in contrast to trauma wounds. So the advice would be that burns excision surgery should be done by five days after the burn, but must be done by a burnt specialist. So the role in the early phase is to manage the physiology of the burnt patient, that fluid replacement, whatever but the weight. So you've got that surgical expertise. So for early infection management, we need to remember that the wounds will be colonized. We need to keep our antibiotics simple and a shorter course as possible. We need to be thinking about wounds that are continuing to evolve beyond three days, when that zone of injury should be fully demarcated. And when those wounds are evolving with beyond three days, we need to think about a couple of things. Have you got a surgical problem, vascular compromise that you've missed or compartment syndrome or have we got an unusual infection, perhaps a fungal infection? And we need to think about infection that is associated with our therapeutic interventions. So, device related just to re emphasis, the duration and spectrum of antibiotic use is keep it simple. We're targeting the ground positives and it's okay to stop antibiotics early once the wounds are clean. But we, you need to remember that central nervous system and eyes are different because of antibiotic penetration. And also the risks of infection here are so great that I think you can justify carrying antibiotics on a little bit longer because losing your eyesight is a disaster, losing a bit more tissue and a big wound. It's a shame but not a disaster. And where we've got gi perforation, we do need to extend our cover to include the gram negatives. But in the context of a trauma laparotomy, if it's done in a timely fashion, that should not be more than 24 hours antibiotics. And again, to re emphasise the antibiotics are not a substitute for good surgery. I don't want to bore you with the shopping list of microorganisms, but just to revisit that the grand positives we're worrying about and I've emphasized them in bold type um Staph aureus, whether it's a methicillin sensitive or methicillin resistant strain. And it's important here to understand your local resistance patterns because that will inform your choices of antibiotics. But when we think about the ground negatives, I use a Charisa coli as an example here. But there's lots of other related species. Coliforms, a pseudomonas that will colonize wounds, but they don't really cause soft tissue infection. However, some of these gram negatives because they're ease with which they can become resistant to antimicrobials will pose as challenges in healthcare, particularly in patient's in intensive care where they might get pneumonia, urinary tract infection. But when we're thinking about the wound, 1 g negative, I do worry about from battlefield injuries, possibility in trauma for that matter is a Ramona's because it can cause a nasty necrotizing soft tissue infection. This is just some thoughts then about the organisms that we need to worry about both grand positive and gram negative and what antibiotics will be of use to treat them. So where there is a black area, the antibiotic is very likely to be effective where there's a gray area, it's going to depend very much on the individual strain of the bacteria. So you can see um if you have a lot of methicillin resistant staph aureus, MRSA, the anti simple antibiotics that we may use commonly such as amoxicillin, clavulanic acid, no useful activity. So here is a really good example where working together as a team allows the laboratory experts with those results. With that understanding, to give you a trauma surgeons and other practitioners, some good best guest choices. And you can see when we look at the gram negative side, there's a lot of gray. So here if we overuse antibiotics, we drive resistance and we leave ourselves with a really problem. And to illustrate that deeper. And I often see patient's who've been injured in other parts of the world where there's a lot of resistance. Patient's ended up with deep seated bone infection deeper. Will ask me what oral agents she can use. When I say I'm very sorry, we've got nothing. So I can't emphasize enough the importance about being careful with what we use because the consequences for the individual patient and the population of patient's are really quite serious. So when should we escalate antibiotics? We have to be practical. But in a critically ill patient with polytrauma, they will have a big inflammatory response and we do not have the diagnostic tools to reliably tell what is the systemic inflammatory response syndrome versus infection? Because the patient is so ill, we probably have no choice but he has broader spectrum antibiotics. But we can still interpret are microbiology results and ask ourselves, is this colonization or is this infection, is this a plausible pathogen in this context or is it just colonization? So we should be very careful about selection pressure. And a good sense check is to ask ourselves, who are we treating? Are we treating the patient or are we treating the surgeon? Are we treating ourselves deeper? Would you like to comment on that from your perspective as a surgeon? Yeah, I think that's right. I think sometimes we, we feel better if we're giving the patient an antibiotic. But by being part of the multidisciplinary team, we learn from each other. And I've realized now that actually it's so important to be very careful with antibiotics to avoid creating resistant organisms. And actually, there needs to be a really good reason to give antibiotics which should benefit the patient rather than just giving antibiotics in case of something. Some thoughts about the role of the laboratory in, in diagnosis. I recognize that we have to be practical and that's there are sometimes when we simply will not have laboratory back up. So we need to think then about what we do with simple things or even nothing at all. So the first thing is that white cell count and c reactive protein of absolutely no use diagnosing infection in the first few days of injury. It is a very inflammatory insult and they will be raised. But what is helpful is when the white cell count crp have started to go down. But then you see going up again, that might be an indication of infection. But you have to remember if you have had repeated trips to theater further debridement, that too is an inflammatory insult and will cause those parameters to rise. And when we think about microbiology, um surface swabs from big wounds aren't particularly helpful. So when you're in theater, if you clean the surface adequately and then take deeper samples or tissue biopsies, that can be more helpful, but you still have to interpret whether this is colonization or infection deeper. Would you like to comment on sampling in theater? Yes. So exactly, as you said, we like to get clean deep tissue samples as much as possible rather than getting swabs from the surface because you're more likely to get a contaminant organism if you do that. But when it comes to blood cultures or other samples such as synovial fluid, which are normally sterile. Of course, samples can be very helpful when they're positive and direct therapy. But blood cultures are a very blunt instrument for diagnosing infection in the trauma patient. And finally, there are occasions when you would want to take samples for histopathology. And we'll come onto that in a couple of slides when we think about fungal infection. So, from our military experience from Iraq and Afghanistan, these two examples, I'm going to show you one of their Ramona's one, a phone call were important. And whilst we saw those particularly from Afghanistan, these are organisms that have a worldwide distribution and would be of relevance to battlefield and injury anywhere. So, a Ramona's, as we have said, can cause a necrotizing soft tissue infection. And whenever my surgical colleagues said the wound was really foul smelling. I was never surprised if we grew Aramony as this of course, assumes that the wound was adequately and timely debrided. And we were lucky that we didn't have problems with that. But the importance of recognizing this organism is that it will not be sensitive to most beta lactam antibiotics. And you would need to add a quinolone such as Ciprofloxacin. But again, we sometimes would grow a Ramona's and the wound would be fine so it can colonize, it doesn't always cause infection. And again, that multidisciplinary team working is really helpful and some thoughts about fungal infection. The new car Elise are a big group of environmental fungi. Again, worldwide distribution, they are reported as causing um infection and it's seen in civilian trauma very rarely. But if you look in the literature you will find examples from natural disasters such as hurricanes where you've got big injuries with penetration of tree or other organic matter. Um uh This infection occurs there. So this is where we would see a wound that is evolving and continues to evolve. At about 7 to 10 days, we saw patient's that had high temperatures. Um And at a time when our plastic surgeons would be thinking about reconstructing, they were still having to debride. And the reason for that is this group of fungi will grow into blood vessels and grow up blood vessels and cause tissue infarction. And you need to be really aggressive in your surgical debridement. If any of you as true as orthopedic surgeons have a sarcoma practice. This is worse than your worst nightmare of an aggressive sarcoma. You really do need to resect and get above the area where you got that tissue about blood vessel invasion. And it's in this group that you really do need laboratory support to grow the fungus if you can, because that can tell you what antifungals would be most helpful, but you absolutely need histopathology to show invasion of normal healthy host tissue by the fungus. And again, the importance of the multidisciplinary team because these are environmental organisms, we would sometimes grow them and our surgeons would tell us the wound is absolutely fine. The patient is, well, it's not a problem. And there are other occasions when they say we've got a real problem with the wound. We recognized in our military patient's that there was a risk group. And eventually we would give them pre emptive antifungal therapy because we believed they were at such high risk of invasive fungal infection. So we recognized that these were uh people on foot patrol in the green zone, lots of lush vegetation and organic organic matter. They had traumatic amputation from treading on an improvised explosive device, big blast injury, driving organic masher deep into tissue planes. They also needed massive blood transfusion because they had massive injuries. And in terms of the surgery, this was a group where injury burden was so high. I think a lot of the time early debridement was absolutely limited by physiology. So the take home message from this experience to think of in other um military injuries is wherever you have a big ballistic injury with a lot of organic matter driven deep. Do you have an evolving surgical wound? Please think about this group of fungi. You could do you want to have anything here? So I agree, I mean, these are very challenging injuries to treat the fungal injuries. And uh exactly as you said, um they needed massive surgical derive mints. Quite a few of them ended up with amputations because of failure to gain local control. So uh you just have to be very, very vigilant with them and to our final summary slide. So prophylactic antibiotics target gram positives, debride treat the patient, not the surgeon. Think about the mechanism of injury, the environmental of injury and endemic infections and your trauma. Patient's remember there are some unusual pathogens but you don't have to remember what they are. Remember who to talk to. Things aren't going well. Don't forget device related infection or no Zuko Me Away healthcare associated infection. And finally remember the multidisciplinary whole patient holistic approach in order to get the best outcomes for these really challenging injuries.