Occupational Medicine Board Review Virtual Course (Includes Digital Syllabus)-OMBR Virtual Clincial Occ Med IV

OMBR Virtual Clincial Occ Med IV

Video Transcription

I'll just close out that, see what we got for our participants.  All right. So it's, let me just make sure I'm unmuted here. We've got a good turnout there, so, okay. We're good. Again, I can't hear myself talk though.  It's the one thing I'm never going to get used to on Zoom.  All right. So there were any questions from last night's episode there? We kind of did a lot here.  Today I decided because there was sort of two in a row that I was just going to make it easier.  So we're going to just look at the pulmonary hearing loss and I forget what the last part of that, there was some travel medicine and ID type questions, although those were sort  of less, there were fewer of those there. So tonight can be a little more freeform. And if there's other questions, and in particular, there's other questions from the first two  lectures. I know somebody recently emailed me on it there, so I may just quickly go through those questions and we'll see who gets on there.  So actually what I'll do is I'll just bring up these questions, I won't pull these on up here, but somebody had a couple of questions that actually pertain mostly to last one.  So there were a couple of, I think four questions. So we'll just kind of go through them in order. So slides on nitrogen dioxide.  So those would be the clinical three slides on the toxicology set that I talked about last night.  And they said there was a slide that said LRT damage, and that just means lower respiratory tract. It was about nitrogen dioxide, oxides of nitrogen.  And so that is a, just to kind of repeat myself from last night, that's a lower water soluble gas, so it's a nonpolar gas, gets its way deeply into the lungs because it doesn't  dissolve in the upper airways. In other words, it's not water soluble. So that it causes amongst other things, I don't have this slide in front of me, but  LRT stands for lower respiratory tract, if anyone wants to make a note. The second question was about the same slide, which was also about oxides of nitrogen, which  is silo fillers disease. And I think I mentioned, you know, one of those little key things that I put down in  the corner of the slides, I, you know, think of some other main points that I wanted to mention or that it's useful in differentiating.  So in the key points I had said, do not confuse silo fillers disease with, and then a whole bunch of other bad things that farmers get.  So what you should not confuse silo fillers disease with, so silo, let me back that up. Silo fillers disease is exits of oxides of nitrogen from fermenting grain in silos.  It gets released when the silo is either filled or emptied, farmer breathes it in. And it's a non-polar gas and gets deeply into the alveoli, causes alveolar injuries  similar to phosgene. So that's silo fillers disease. So don't confuse it with a farmer's lung. So farmer's lung is a form of hypersensitivity pneumonitis.  So that is an allergic reaction, probably a type three hypersensitivity, but it can be partially, probably a whole raft of them, type three, type four, and possibly two.  So farmer's lung is a kind of hypersensitivity pneumonitis, and that relates to fungal and atypical bacterial allergens that are on grain.  So the farmer is potentially at risk from the silage from both oxides of nitrogen from its fermentation and from farmer's lung or hypersensitivity pneumonitis, which isn't  from the grain itself, but is from bacteria and fungi that grow on the grain. Organic dust toxic syndrome.  I think we cover that later in some of the other slides, but that is an inhalation fever. So it's much like metal fume fever.  And this comes from endotoxin, usually again from bacteria, gram negative bacteria that are residing on grain.  And so inhaling those gives people an inhalation fever, which are usually rather dramatic.  They're a fever, chest tightness, some dyspnea in the settings of normal labs and the normal chest x-ray, and it resolves pretty much on its own. So similar to metal fume fever.  Organic dust toxic syndrome, or ODTS, comes from bacterial endotoxins on grain or chaff. And hydrogen sulfide knockdown comes from manure pits.  So four things that farmers can get all fundamentally inhalation injuries. So silo fillers disease, farmer's lung, ODTS, and hydrogen sulfide knockdown.  Somebody had a question about treatment for pesticides and treatment of organophosphates and a little bit of sorting out atropine and the antidote, which is pralidoxime or 2-PAM.  And they're used for the treatment. And somebody had come across a question, I think in another series, which asked which of the two should be given first.  And so one basic point, maybe I'll just enlarge on this a little bit, just because I have a little bit of time to talk, is that atropine reverses symptoms.  So it's simply symptomatic treatment. It doesn't destroy the acetylcholinesterase inhibiting activity of the OP pesticide. So you give atropine for the same reason.  Similarly, actually, if you want to think about it in general medical terms, you give it to reverse the symptomatology.  And that are the secretions, the bronchorrhea, the salivation, lacrimation, urination, diarrhea, and the like. And so atropine reverses those.  And importantly, it reverses what you call the killer bees, the middle of that mnemonic  of dumbbells, the B in dumbbells is for the killer bees, which are bronchorrhea, bronchospasm, and bradycardia. So atropine will reverse the bradycardia.  So you want to give atropine. So the question was which one is given first. And what you want to do is reverse the symptomatology first.  And so you give atropine, the bradycardia stops, they get back up to a normal heart rate, the secretions stop, they stop being uncomfortable, the bronchorrhea stops.  And so you've reversed some of the real life threatening problems. And the reason you also give that first is if you really want to document that this is  an OP pesticide poisoning, you can give atropine and reverse the symptomatology, but it doesn't affect cholinesterase in the system.  So you can give atropine, get your patient stable, draw a cholinesterase level document,  send that off to the lab, then give the antidote, which is pralidoxine 2-PAM for the treatment.  And that actually breaks the OP phosphate bond, and it reactivates acetylcholinesterase. So if you wanted to document it first, you don't want to give the antidote 2-PAM because  it'll reverse the actual bonding and inhibition of the enzyme. So that's why you give it first. And atropine, you just get the symptoms reversed and get them out of there.  So anyway, hopefully that is of use here. And now that, let's see if there's anything else in there.  Prophylaxis for hepatitis B exposure, somebody wrote, and there's non-responders at the bottom of the slide.  And so there is a, these are straight from the CDC, so they're a little bit difficult to explain.  So a non-responder is somebody who has had either three doses or six doses of hepatitis B vaccine and has had antibody tests drawn and has not made hepatitis B surface antibody.  And so that is a non-responder. So you give it once, one dose of three, check it. If it's negative, you give a second course of three vaccines, check it again.  And then those people become either one series or two series non-responders. And so the worst place to be in probably is the two vaccine non-responder because you  really haven't responded to the dose at all. That differs from the response unknown, which you may be running into perhaps more frequently  as people have these vaccines in infancy and childhood. And so you may be running into people who have an unknown response and you draw an antibody  test when they become stuck and they have an antibody response less than 10. So that is a possible or a probable responder versus a non-responder. And so that makes the difference.  And usually the non-responders are the ones who usually should get, you know, you really have to treat them with hep B, immune globulin, H big for the response unknown people.  Depending on their antibody response, if they have some detectable antibodies, you can usually just boost them.  Otherwise you might want to think about also giving them H big, particularly if it's a infectious patient, if they're hep C antigen positive for E antigen positive.  I didn't mean hep C, I mean hep core or E antigen positive. Okay. So that kind of covers some of our things.  And if anyone else has any other questions, let us know, or you can also email me about those there.  Those are some of the questions I'm getting. And then it's probably useful because if one person has a question, it's probably confusing more than one person.  So I think the pulmonary slides are rather short here and let me just try and find them. All right. And we've got that up here. Okay.  So in some fairly straightforward ones on pulmonary, I'm going to just say at the outset here to, I'm not sure how many, I can't sort of count up who's taking the boards for the  first time versus who's taking it as a research exam. But there are a couple of slides, and I think I mentioned it in the tapes, is that no one  expects you to become a B reader for this course. So you don't have to get a, you're not going to get a slide. You're not going to get a chest X-ray on screen.  You're not going to get any of those and have to be read it and decide whether it's a 1-0 or a 2-1 or a 2-3 or fill in the blank on the B readers. Nobody's going to do that.  That's straight up for the B reader exam. What you want to just know is about the system and the system in that it grades profusion of opacities.  In other words, how many there are, what the density of opacity profusion are, and their  size and shape, again, round opacities, round regular small opacities being typical of silica  and coal, and generally in the upper zones, linear streaking or irregular opacities, more typical fibrotic lung disease, more typical of asbestos, and typically in the lower zones,  in the lower lung zones. So you want to kind of remember those. That's about the limit of what you want to do for B reading, other than saying that perhaps  it was designed for epidemiology. Question from somebody here, will a reference listing for lab values be given on the test?  And the short answer to that is yes, if there are lab values. I think the only case you wouldn't see a reference for lab values, I'm trying to think  if there's really anything that they did, I would know what sort of, you'd basically want to know, for lab values, I think the main thing you want to know is lead.  I'm not sure if they would give you lead values, but some of those established values are, not that they're sort of normal and abnormal, but you want to know about keeping pregnant  women certainly below 10 mics per deciliter, and ideally below five mics per deciliter, and about the OSHA medical removal protection standards, which are in the very last set  of slides, which is the standard for medical removal protection, depending on which standard it is, construction versus general industry is either 60 or the average of three that's  50, but for construction standard, it's 50, and you don't return people out of medical removal protection until it's 40.  So short answer to that is know your numbers about lead, anything else, they're most likely to give you laboratory values, normal ranges, although I can't really think of any place  where they actually did give you lab values other than that. You might see one there and that kind of thing, but they do, but I would commit lead to memory as much as possible.  Okay, so the mean latency for the appearance of bronchogenic carcinoma following asbestos exposure is approximately, so two years for lung cancer.  So the latency, just to kind of remind you of the definition, latency is the period of time from the first onset of symptoms until the appearance of disease, and so think for  most carcinogens that it's generally long, right? Cigarette smoking and bronchogenic carcinoma is a period of decades, and that's fundamentally  going to be about the same for the appearance of bronchogenic carcinoma. So the mean latency for that is going to be all the way at the bottom down to about 25 years.  I'll get to that in another question rather than asking you some other thought questions because this appears again in question number four.  Okay, so moving on to the next question, giant cell pneumonitis is part of the clinical picture  of, and take a look at this, let's go through the choices here, coworkers pneumoconiosis. That's not true. You don't see giant cell pneumonitis, specific cells for that.  Coworkers pneumoconiosis, remember, is small rounded opacities followed by confluence of opacities and progression of those opacities, little fibrotic areas into confluent fibrosis  and eventually progressive massive fibrosis. So that's coworkers pneumo. Silicosis, I could just repeat exactly what I said before, small rounded opacities becoming confluent.  Hypersensitivity pneumonitis, so I'm not sure how much we covered that in here, but sort of typical pictures or pathologic pictures.  But in late HP, you'll just see interstitial fibrosis, HP in its early stages. One good way to remember it is HP is what the Brits call extrinsic allergic alveolitis  or EAA, extrinsic allergic alveolitis. And so in its early stages, what you get is an inflammatory picture looking more like alveolitis. Occupational asthma, you tend not to  biopsy those. I'm hoping nobody picked that as a potential answer there. And so D, you're left with hard metal disease and so that is the answer here. And so  hard metal disease is a consequence of adding cobalt to machine tools in order to make them harder. You're adding it fundamentally to tungsten carbide steel  plus cobalt makes a very hard machining metal tool and you make those so that you can grind and machine other steel tools. You have to have something that's  harder than those steel tools to be able to grind and machine them. So fundamentally hard metal disease is an allergic reaction probably most likely a  type 4 reaction to the addition of cobalt and inhalation of cobalt in people who grind and make those with it. Okay, so moving on here. All of the  following are useful for the diagnosis of occupational asthma except which one? So is cross-shift spirometry useful? And the short answer to that is yes. What are  you doing with cross-shift spirometry? Usually on a Monday morning, they've been off for the weekend so they've had two days to recover. You put them on the  spirometer at 8 a.m. in the morning, have them do FEC and an FE1, do the standard spirometry. They work through the course of the day and then at 4  o'clock or 5 o'clock whenever the shift is over, you put them on the spirometer again and see what the difference is there. And in the case of asthma, what  you're going to see is a drop in FEV1. You're going to see evidence of pulmonary obstruction. And generally, so you can think of it as kind of the  reverse of giving it somebody a bronchodilator, you know, they improve 10-12% here. In those cases, if you get them in the morning and get them in the evening  and if they have dropped about 10%, which is sort of a the kind of averagely used criteria for this, it's a potential bet or sort of good evidence that this is  somebody who has asthma that's related to their job in the workplace. Again, doesn't tell you what the substance is but it's asthma in the workplace. So  they've dropped their FEV by 10%. You can also do cross-shift on Monday morning and Friday afternoon and they've gone an entire week for that. Okay, so that's  useful for diagnosis of occupational asthma. Serial peak flow rate measurements, much the same thing. Those of you who would have looked through the  slides already would have seen the charts and what you see is kind of a sawtooth if it's related to work, is that you see them normal. So they go along  Saturday, Sunday, their peak flow might be about 600. They go to work and they get on the peak flow meter and suddenly it drops down to 400 and stays  down there the week, a couple of hours when they do it again. Goes back up at nighttime when they go home and so the peak flows now at a normal and you see  this kind of jagged sawtooth pattern. Usually a drop of about 15-20% in peak flow rates is indicative again of something going on in the workplace. You  want to get a good baseline where they're home and then get them at work for several days. Okay, so that's useful for asthma. Diffusion capacity, so  what's diffusion capacity useful for? So that's a measurement of fibrotic lung disease. It's gas transfer across the alveoli and that's  going to be interfered with, not in obstructive lung disease where the problem is the airway, but here the problem is fibrosis and around the  alveoli and gas transfer into the pulmonary circulation. So that's not the useful one for a diagnosis of occupational asthma. So that is the  answer to this question. Just look at the other ones. Serum IgE or RAS testing to specific antigens can be useful. Usually useful for the biologicals, high  molecular weight allergens, animal danders, detergent enzymes, wood dusts, things like that. They're not as good. The IgEs or related tests aren't  particularly good for the small molecular weight allergens like isocyanates. They're being developed but they're not great right now. And specific  inhalation challenge, this is great for asthma if you can get it. Generally it's done in Canada because they have specialized centers for it, but not in  the United States. There's some centers that do mainly research around things like isocyanates. Okay, which is the earliest clinical manifestation or  shortest latency? Remember up in the first question we talked about latency and bronchogenic carcinoma. So which of these has got the earliest clinical  manifestation or shortest latency of asbestos exposure and which is the latest or the longest latency? So we looked at lung cancer that was about 25  years or so roughly, maybe even a little bit longer. Mesothelioma is sort of the biggie and that's got a very long latency. So the average or mean latency  for that is probably about greater than at least 30 years. So you can hang a number on it anywhere from 30 to 35 and they can show after 50 years. So there's  cases of people who worked with asbestos in high school jobs, summers from college, those type of things, and then in their 50s developed mesothelioma  subsequently when they didn't have any exposure. So that's really long, so anywhere from 35 to 50 years. So that is our answer to the second part of the  question, which is the longest latency. Asbestosis is somewhat less than these other two, so you generally require about 20 years of exposure. If it's very high  exposure, exposures you really don't see very much anymore since asbestos was banned, but it could have been about 10 to 15 years now, really probably about 20  at moderate levels for asbestosis. So that's somewhere in the middle. So this is one of the questions the boards really loved back in my day anyway about  sort of very trivial, very trivial sort of things you had to remember. But a benign pleural effusion is the longest latency disorder and that actually has a fairly  short latency of about 10 years or so. So 10 years for benign pleural effusion, anywhere between about 10 to 20 years for development of pleural plaques and  then subsequently asbestosis. But benign pleural effusion usually isn't noticed unless you're looking for it, unless they've had heavy exposure and they're  getting their x-rays regularly under the standard. All right, so the answer here, sort of part A to that answer, is benign pleural effusion, a latency of about 10  years mesothelioma, about 30, 35 plus. Degree of synergy multiplicative risk between smoking and asbestos for the development of pulmonary mesothelioma is  approximately, I'll let you take a look at that there, and I don't know if anybody  wants to raise their hand. It feels like raising their hand and answering that. So the degree of synergy, this is a bit of a trick question and I hope you didn't  answer 55, which is usually what you have at your fingertips, because this question didn't ask you about lung cancer, it asked you about pulmonary mesothelioma.  And so the synergy between smoking and mesothelioma is that there is none and  so the answer here is zero. The way to remember that is that if it were related at all to smoking or if there were synergy, you would see a lot more  mesothelioma cases in smokers, and as best we know, smoking is not a risk for meso, whereas asbestos is, you know, you can't say it's 100% absolutely certain,  but it's pretty pathognomonic for mesothelioma. There are a few spontaneous cases without it, but most people do have a history of exposure. So it's zero.  Remember that that's a bit of a trick question. I apologize for you, but it's probably better that you get caught now when the stakes are low than when you're  taking the boards and you don't get that. Okay, number six and moving on to infectious disease. Following is recommended for evaluation and control of  TB in occupational settings, hospitals, and related. Now here's a, here's, and I think I entered this into the slides there, the recommendations for  surveillance programs in health care settings have changed and fundamentally now the recommendations are not to do this annual PPD that we've all known and  loved ever since, you know, we were young and in medical school, but to do initial PPD testing and then to do them in response to suspected exposure, suspected  or known exposures, or an evidence of any, either kind of exposure or evidence of developing TB. Now that said, that is relatively new and because the boards  won't have gotten to it yet, their questions usually have a pipeline of at least 18 months or so. So anything dealing with a new new recommendations  from the CDC about evaluation control and particularly surveillance in the occupational setting isn't going to be active, at least for the boards this  October. For next October, I'll change around all my lectures, but the way to think of it now is just to think of it as the same old one you always learned.  So anyway, here, so single PPD testing for newly hired employees, is that recommended? No, it's not. You use a two-step PPD for newly hired employees,  particularly if they have not had evidence or demonstration of a continuing line or chain of PPD testing. So you want to do a two-step because if  people were infected, they generally were infected a long time ago, their immunity has waned, and that first dose of PPD becomes a booster dose reactivating the  immunity, and then the second PPD a week later is, if that's positive, that's evidence of a boosted reaction. All right, so that's not. Second recommendation, use  of a five millimeter cutoff for a positive test in current employees, is that correct? No, that's not. So the cutoff for a positive test in employees is  what? So that's ten millimeter, right, along with people with silicosis, separate from healthcare employees, so it's a ten millimeter cutoff rather than a five  cutoff. Excluding employees who have a positive PPD and negative chest x-ray from working unless they undergo LTBI prophylaxis or latent TB prophylaxis, so  that's not correct either. If somebody has a positive PPD and a negative chest x-ray and they're not sick, they're not febrile, they're not coughing, they're not  coughing blood, etc., etc., they can go ahead. There's lots of reasons why people cannot take LTBI prophylaxis. They're slow acetylators and they get liver  damage, or they are older and get liver damage, but all of that to say is that  if somebody converts their PPD and they're otherwise clean, no evidence that they're infectious and therefore they can continue to work. And so the last one,  including employees who have had BCG as children and routine employee PPD testing and surveillance, so that is the correct answer. On the slides I showed  there, the CDC, I'm quoting chapter and verse from the CDC, which is that you don't exclude people who have had BCG as children, young adults, because the  immunity conferred to that wanes. And if you have a reaction above the cutoff, the possibility or probability is that that represents an exposure with everyone  else. Now, I know all of your experience varies from that there, and anybody who works in hospital employee health has their own stories about people demanding  exclusion from that or saying that they had BCG and were told never to have a PPD, etc., etc. But what I'm doing here is teaching to the test, and the test is  going to quote the CDC recommendations and the CDC recommendations so that you don't exclude people with BCG from surveillance. Okay, moving on. Everybody  still with me? Nobody's dying here? Okay. Interfere on gamma releases for TB infection. So this has changed the ballgame a little bit from the PPD. Do  they represent the current gold standard for diagnosis of latent TB infection? Not exactly, no. They are particularly, I think, in its early use  they're getting a little bit refined, but if you apply them to a population who already have a low incidence and or prevalence of latent TB infection, you're  going to get a lot of false positives. So the cutoff is really drawn where you think you can differentiate the true positives from the false positives, or  the true positives from the true negatives, but on either side are going to be true positives and false negatives. In a lot of cases, when some places  instituted interferon gamma assays for these, they wound up getting a lot, they had, you know, a 1% or 1.5% incidence of PPD conversion, and then they got  suddenly about a 4% or 5% incidence of positive interferon gamma assays, and all that is to say that they're the false positives of testing low  prevalence group of people. So you can't necessarily call it, it's a lot better probably than PPD if used across the long run. You can't necessarily call  it the current gold standard yet. Are they too expensive and cumbersome to replace TST testing for workplace surveillance? No, there's upsides and  downsides for doing both, and some places find that, for example, the indirect costs of doing skin testing, which is people have to leave their jobs, come in, they  have to come in twice, etc., etc. It costs a lot in the staff reading them and the like, so the indirect costs may actually, the improvement in indirect costs of  doing interferon gamma assays may actually outweigh the bad side or some of the expenses of it. Do they show boosted reactions from prior BCG  administration? No, that's not accurate either. They will not show a reaction from somebody with BCG, which gets you around the problem from the previous  question, and as well, it's a whole set of antigens that are specific to mycobacterium tuberculosis and not to the BCG strain of it, and so therefore  you won't get a reaction if you give it to somebody who's had BCG but hasn't been exposed to TB. And do you improve compliance with workplace TB surveillance  programs? So that's the correct answer. They can improve compliance with it. Again, the whole problem of people having to come in annually for the TST, having  to come back in 48 hours, they miss it, you want to know, you give it again, you call them up. Lots of person hours spent in the employee health service trying to  run those down, so they can distinctly improve compliance. You got one visit, one and done. All right, which statement is true about hepatitis B vaccination?  A, it is no longer mandated by OSHA since infants and children are now vaccinated. That's not true. It is mandated by OSHA. Most residents of the  United States are getting vaccinated as infants and children, but some may not have parental choices, fell through the cracks in vaccination programs, or come  from overseas where it's not quite as widespread as here. So OSHA mandates that you offer a hepatitis B vaccine and that the employees sign a declination form  if they're not going to have it. A six-dose non-responder should be checked for a hepatitis B surface antigen. So that is actually true.  And one of the reasons why there are some health reasons why people aren't responding to hepatitis B vaccine, but in general, if you're vaccinating employees  of a health center and they haven't had it and they're not responding to the two sets of three doses, one option is to check them for a hepatitis B surface antigen  and make sure that they're not a chronic carrier because in that case, they wouldn't react to the vaccine and they would want to know.  It requires boosting every 10 years as titers wane, and that is absolutely not true. So people do mount an anamnestic response to the hep B vaccine  if they're challenged with an antigen 10, 15, 20 years out. And so I know, again, some employee health places check sometimes new employees, check hep B titers,  give a booster dose, et cetera, et cetera. That's not the recommended course, at least, not by the CDC and the MMWR recommendations. So, again, teaching to the test,  that's not the recommendations for it. And lastly, pregnant women should be excluded from the OSHA vaccination mandate. So here, what's the question?  The question is, this is not a live virus vaccine. It doesn't set up hepatitis B infection. And so, therefore, it is acceptable for pregnant women  and should be given, same as anybody else. So the answer here is B, the one statement that's true in that. Okay, the annual audiogram for a 25-year-old machinist  reveals a hearing level of 45. In other words, they've got a 45-decibel decrement in the left ear at 4,000 hertz on a retest after a 14-hour noise-free interval.  And it's otherwise normal, less than 25 across all, I should say, all other frequencies in both ears. The most likely cause of this result is which one of the following here.  So what are you looking at here? You're looking at a unilateral hearing loss, one ear, otherwise normal. So the most likely cause, I think Peter Rabinowitz wrote this slide,  and as I'm looking at it, I can see that there's potentially actually not. It's probably right on it there. So there's this occupational noise exposure, as we generally think of it.  You know, sound generally comes at people bilaterally. And so with usual, typical factory floor or logging, lumbering, mining, et cetera, both ears are exposed.  And so you have bilateral hearing loss of approximately the same. So it's not choice A. Meniere's disease and acoustic neuroma are going to show decrements in a range of frequencies  across the spectrum. So instead of a notch at 4,000 hertz, you're going to get more of a lower but flat audiogram. So all hearing levels from 500 hertz  on upward to the higher frequencies are going to be affected in those as well. The Meniere's disease person may also have vertigo and some other symptomatology.  And so, again, Peter Rabinowitz writing this one. It's exposure to noise while performing recreational rifle shooting. Couple of things to remember.  There's a couple of causes of seeing unilateral noise induced hearing loss, which is what I think he was trying to telegraph by this notch at 4,000 hertz.  But rifle shooting, because of the way it's held, it's closer to one ear, whereas the other ear is pointing in fundamentally the opposite direction  and not subject to the sound shockwave that the proximal ear is subject to. And the other one is potentially ambulance drivers or anybody with a siren, whom in the United States  is going to have trouble with their left ear as a consequence because they're driving, the siren is over on the left side, or they put it up on the hood.  They have to leave their window open. Somebody tells me there's some mandates for that. And they may develop unilateral hearing loss in the United States and the left ear.  In the UK, I expect it would be on the right. Excuse me. All right. Traveler returns from a month-long trip to multiple regions in Africa to oversee humanitarian operations.  He presents to clinic reporting daily fevers, fatigue, and headache. And the most likely diagnosis of this is going to be a little bit of a choice here between.  But the fatigue and the headaches generally I think sort of typical of malaria, although I wouldn't fault you for picking dengue fever. And I'll have to ask Peter.  So this will be more for you in the next segment or slide as to whether or not dengue fever versus malaria might be the operative one.  Probably the month-long trip was part of the clue here. All right. A college student presents for pre-visit travel prior to a planned fall semester away in London.  These were written a while ago, several months ago. And so a college student did plan on traveling to London and either going to college or traveling to London.  It seems like ancient history now. So this college student presents for pre-visit travel planned a semester away in London, which vaccinations are recommended prior to travel.  Is typhoid? No, the water supply is generally good. The exposures are not going to be high. Drinking water, if you're going to be using it out of the tap,  is in general either chlorinated or ozonated and filtered. And so for England, that's not going to be a problem. Yellow fever, it's not a tropical country, not yet,  although with global warming, there are actually wine-growing areas in England now. But yellow fever hasn't made its way up there.  Influenza, so you've got a kid going to the fall semester away. They're going to be there from September to December. Yes, influenza is a potential threat to them there,  and so they should have an immunization for influenza. And Japanese encephalitis virus, again, not endemic to England. So that kind of completes that.  I probably talked more than I should here, but I had a shorter one here. So I hope I've enlightened you a little bit more. Let me just pull up the chat here.  Would I please review the threshold shift scenario in the lecture, specifically when the baseline is reset? So is everybody OK on that? All right. Let me find these slides.  So this is going to take me a short bit here.  And Peter has written extensively about hearing loss, and so I find that he's  a better explainer for that.  And I'll just bear with me while I pull up the slides here.  Almost there.  OK.  So bear with me here, and I'm going to stop that share and try and find the slides to show the screen with here.  All right. Can people see the shared screen? I should have some of that. The shared screen, I should have some slides up on it. We can see it. Excellent. Thank you. OK.  Glad one person didn't answer. OK. So let me just pull that up to here. So the concept, a couple of concepts, and thanks for asking this here.  Again, Peter's great in outlining how this works, but he wasn't able to do this for us here.  Down at the bottom of this slide here, let's see if I can find a pointer. OK. So there is a, give me a second here. Yeah, so I'm going to look at the practice calculations  in a second. So here's a, the OSHA, let me put it a different way, a standard threshold shift regardless of recordability. So what you would call an SDS, standard threshold shift,  is going to be a 10 decibel average shift from their baseline at 2, 3, and 4,000 hertz. So if they started off, let's just say a nice case scenario,  they started off at a flat 0 on their first audiogram. So the first standard threshold shift, the first time they hit a standard threshold shift,  is going to be the average at those of 2, 3, and 4,000 hertz, a 10 decibel average. So if at 4,000 hertz, you have 20, and at 3,000 hertz,  you have 15, and at 2,000 hertz, you have 10. So that's 20 and 15 and 10. So that's 35, 45. So that's going to be an average of 15 decibels, the average shift.  So that is a standard threshold shift. Now, that's a threshold shift or standard threshold shift. It doesn't become OSHA recordable  unless and until also the overall mean hearing level is at 25 decibels or greater. So that means that the shift that it went down from 10 decibels to an average of 15 decibels  is not OSHA recordable because that overall mean hearing loss was not greater than or equal to 25 decibels. It was 15 decibels. So you have to wait until the overall mean hearing  level at those areas is 25 decibels as well as the shift. So let's take a look at, let me see if I can advance this, which I seem to be having trouble doing.  Bear with me a second here. OK, it must be for the pointer. So let's look. So again, this is repeating itself here. OK, so here is the, let me find the pointer again.  So here is the reference audiogram. So we're really just going to look at these three frequencies. And so somebody starts a job, their audiogram is working down from 4,000, 10, 10,  and 0 at those three frequencies. They go through, they don't have much of a change here. Let's just look at the second annual. So what's the mean change?  The mean change here is 15 minus 10, so that's 5. 10 minus 10 is 0, 0 minus 0 is 0. So it's 5 divided by 3, which is less than 2. OK, so we kind of move on through it here.  I'll skip the next one. At the fourth annual, now let's calculate this again. So the change here is 20 minus 10, which is 10. 15 minus 10, which is 5. And 10 minus 0, which is 10.  So that would be 10, 5, and 10, which is 25 divided by 3, which is 8. So they still haven't hit it yet. So now I'm going to kind of move it on here  and show you how that right answer is calculated here. So the first OSHA recordable threshold shift happens down here at the fifth annual. So 30 minus 10 is 20. 25 minus 10 is 15.  15 minus 0 is 15.  So it's 15, 30, and 20. So that's 50 divided by 3, which is going to be more than 10 anyway. Let's see, did I put that in there?  OK, so 15, 15, and 20, so that's a 16 decibel average shift. Now the problem here is that the overall mean over here hasn't yet hit the OSHA threshold, right?  So if everybody can see this, the overall mean at this fifth annual visit is 30 plus 25 plus 15 divided by 3. And so that is 23 decibels, which  is just under the OSHA threshold for that there. So while you have a standard threshold shift, and that actually would have occurred, I think, back up here even.  But you have a standard threshold shift over in here. The overall mean is not yet OSHA recordable. So what you do have is this became the new baseline  because it was a standard threshold shift. This is confusing, OK? But it didn't become OSHA recordable. This is now used as the new baseline. This fifth annual one.  And so what you have is, do the math over here, 50 minus 30, 45 minus 25, and 30 minus 15. So it's this minus what became the new baseline  because they had a standard threshold shift. And now that's a 15-decibel average change from the previous one. So that's more than 10-decibel change.  And the overall mean is now greater than 41 decibels. So I'll just kind of interrupt this a little bit and say that this is not something  that they will expect you to kind of calculate. We sort of calculate this as an example for you to sort of see the difference. In real life, most of you who have  done audiometric surveillance have a computer all do it for you so you're not sitting there with a pencil and pad and trying to sort of scratch it out there.  We do put this in there because the OSHA standard is a bit confusing because in real life audiometry and in hearing conservation programs and in the ideal world where we're  taking care of our patients. I'm going to skip back a moment here if I can.  I might not be able to get there now.  In the real world where we're taking care of our patients is that a standard threshold shift is something we should concern ourselves with.  So that 10-decibel average shift from the baseline. That means there's noise. That means there's noise that's not well controlled. Does the worker notice a 10-decibel average shift  in there? We hope not. We hope it's from 0 to 10 or from 10 to 20 and they're not noticing very much. But what it does say is that the workers shouldn't  be losing their hearing like that. They shouldn't have shifts that kind of go down into the speech frequencies at 2,000 and 3,000 hertz and cause a standard threshold shift.  And what that means is that noise in the factory is not well controlled. So in the real world, this is our standard threshold shift.  the underlying point of showing you the numbers is not that somebody's going to make you calculate it there, but that the OSHA standard calls for this STS shift of  the baseline if there is a standard threshold shift, but OSHA reportable only if the overall mean hearing level is greater or equal than 25 decibels.  So that's really, I think, the take-home point we want from this here, and the calculation is something that I think, you know, nobody's ever told me that there were calculations  for it or anything like that, and I've never seen that. So they won't be throwing that at you there, but you want to remember the definition of  the standard threshold shift plus that OSHA standard threshold shift. All right. So hopefully that helped, and hopefully I didn't confuse you more.  What I'm really hoping is that what's really the take-home message is on the slide here. Okay. Some other questions.  Are there going to be four or five answer choices for OM board questions? There's always four questions. It's always and only four questions.  It's best one, and there are no matching questions like the one we had for yesterday's session.  Yesterday's session was mostly just, you know, matching is just a help to taking tests or reinforcement of the information, but in the boards, it's always four questions, and in  general terms, I'm not sure if they hew strictly to this there. I once wrote questions for a year or so for the National Board of Medical Examiners on  EPI, and they made you never do a which one is not. In other words, gave you three right choices in one, you know, which one is it not.  They always have to have a, you know, which one is the answer in the positive sense. So that's a little bit of a point there.  I think the board has enough people with experience in writing questions to do that, but I'm not sure, but it's always going to be four. It's always going to be multiple choice.  It's always going to be four, and it won't be matching. Next question is, are there questions with audio clips on the test? No.  There are pictures and, you know, usually things like x-rays. So look at the x-rays in the pulmonary section. Excuse me.  Look at the questions in the pulmonary section and the x-rays. Those are the pictures you're going to do.  Other pictures that would be useful for you, basophilic stippling in lead poisoning.  I know in the very last lecture, the OSHA section, I've got a picture of basophilic stippling. Francesca might have had one as well. All right.  Can you mention the type of respirators that are used during asbestos building remediation? So for asbestos building remediation, sort of a tricky story because you generally have  to have an impermeable suit because asbestos is so fine that it gets everywhere. But the best respirator, the minimum use respirator for asbestos remediation is something that's  going to remove 0.3 micron particles. So it has to be an N95 or better. And in general, you also want eye protection because the potential of it, you know, getting  in the eyes, cornea, that type of thing, they're very fine fibers. And most remediation is usually done in impermeable body suits like the Tyvek suit and things like that.  So you want to have a respirator that goes along with that. So oftentimes they're sort of built in Tyvek suit respirators with a particulate respirator  that is at least as good as an N95, in other words, filtration of particles, 0.3 microns or later. There's more on respirators at the tail end there.  One other question I'm getting, does the board have all of the above or none of the above questions? No.  So you get like three choices and a fourth one that's none of the above or a fourth question that's all of the above.  It's sort of, you know, one this, two that, three, the other, and four, a fourth choice. So you got four choices, no, none of the above, no K-type questions.  Those are really going out of style and for learning practices, they're actually terrible. It favors test takers and that type of thing.  Does OSHA allow correction for presbycusis and calculating hearing levels for standard threshold shift? Yes, they do.  And that's probably a good point to remember there is that you can correct for presbycusis. Now here's where you really need a computer to do that then and computers will do that.  You plug in age and they will give you the correction for presbycusis, calculate a standard threshold shift corrected for presbycusis and it may, you know, it will be a little  bit lower because the program will then adjust it for age which would be hearing levels considered to be a consequence of noise getting adjusted downward.  Now I don't want to get on my soap box and that kind of thing. You guys all want to go to bed or read or whatever.  But here's the thing is that there's a lot of argument that there really is no such thing as presbycusis.  There might be some conductive hearing loss from ossicles getting arthritic or old or what have you there.  But the main argument is that there are indigenous peoples in parts of the world who have never been exposed to factory noise or any other sort of loud music or anything like that.  And they hear the old people in these indigenous peoples hear perfectly. They've got, you know, zero decibel thresholds. And so anyway, what was I going to say?  And so it's considered that presbycusis is really exposure to noise across a lifetime there. But that said, and now I'll get off my soap box, OSHA does allow correction and this is  where you need the fundamentally you need the computers to sort of plug in, calculate the standard threshold shift, subtract for presbycusis or correct for it, and then spit  out the reportability or recordability. So next question, has Prometric mentioned if the centers will be mostly open and operating in October? I don't know.  I think I would go to their website and I would maybe ask the maybe they've had some words from the American Board of Preventive Medicine, the ABPM, who administers the test.  I don't know and I haven't checked that. One underlying point here is that the ABPM and I firewall from each other.  They don't want me knowing the questions in advance and I don't necessarily then bother them about that there.  And they sort of change that their courtesy send me out things, but they haven't mentioned it there and I have to say I haven't heard if the centers will be open and operating  for October. So I think probably address that to the ABPM first and hopefully they'll then put out a  blast announcement hopefully to the ACOM membership, the residency directors, the OEM mail list, places where people can find that things there.  All right, one or more of our practice questions have asked about latency. Should you be able to touch upon the most tested latency periods for diseases of interest  on the boards, pulmonary related or body systems? I think the main thing with latency is really I think with latency, you are talking about  cancers and the latency of tissue cancers, sorry, must be blanking here a little bit  on it there. Nature of solid tumors fundamentally is generally about 25 years plus, 20 to 25 years plus.  You're really talking about lung cancer and you're really talking about those with things like mainly asbestos I think would be the appropriate thing for latency.  Asbestosis and the manifestations of asbestos, I think it's good to have sort of a feel for latency of some of those there.  But aside from that, I think it probably goes to sort of the heart of solid tissue cancers generally in the sort of 20, 30 onward years up.  Hematologic malignancies, of course, much sooner. So ionizing radiation and hematologic malignancies going to be much less up and around somewhere  starting after about five years, progressing on up to 10 years. And that would be true of radiation. That would be true of benzene, for example.  And then most of the other cancers, aside from that, related to occupation are going to be solid cancers.  And as far as latency for other disorders, most of them sort of, most are very erratic.  So I think, for example, if you're talking about non-malignant disease, things like sensitization  for asthma or sensitization for allergic contact dermatitis has to occur of a period of running of sensitization, but those can be long or short.  People can exhibit sensitization in three months and develop asthma, or they can go for a couple of years, oftentimes working in, if people take care of animal handlers  in hospitals, like people who develop allergies to mice, rat danders, things like that, may have a longer latency for that there.  So they aren't very specific, but I think the main things you would look at would really  be sort of the, between the hematologic malignancies versus solid tumor cancers and mostly related to asbestos. So hopefully that helps answer your question there. All right.  What time is it anyway? So on the East Coast, I have about 10 past nine. I thought it had gone later. Any other questions? I'm going to stop this sharing here.  See people, you know, certainly people feel free to email me with any other questions. I think we went through some of those on an email, and I think Francesca is up next.  And so I think for her questions, probably, where's the money going to be on her questions? Probably in the commercial drivers, drug testing, emergency response.  So if everyone wants to be prepared for that one, and barrage Francesca with questions tomorrow, go through that one, because that's the stuff she knows well, does well, and that's  where the money will be on tomorrow's phone in for you there. So if you want to do one thing or to kind of keep up with other of the questions that  she might be covering, look at the module on drivers, exams, drug testing, and emergency response. So other questions?  Work restrictions for health care workers with positive hep B antigen, right. It is all over the map, and I mean, that's both sort of figurative and literal.  The CDC only said that hospitals, quote, may exclude persons with infectious hepatitis, so that would be somebody with a positive hep B antigen, particularly if they're E antigen  positive, from, quote, exposure prone procedures. And they gave some examples or sort of, let me put it this way, I trained as a surgeon,  and you'd get screamed at by my chief for doing these sorts of things, which was palpating a needle.  So you're in very deep, you're driving a suture needle through that, and you try and palpate the tip. Well, you're going to stab yourself, right? That's no brainer.  So that's why you used to scream at me. And so, but anyway, sorry, on another thing, but anyway, so the CDC lists those sorts of  things like blindly palpating a needle in an enclosed space, et cetera, et cetera, as an exposure prone procedure.  Now, what has happened is, because the CDC didn't offer a lot of guidance on that, is that state departments of health have taken it upon themselves to write regulations about  how that's done. And there's a tricky balance between the individual's rights, particularly under something like  the ADA versus the hospital's need to keep the public safe and the public health aspects of running it.  So for example, in New York state, if there's an identified person, people are supposed to self-identify, which is one issue in and of itself.  And then once self-identified, you're supposed to convene a panel, which generally includes somebody from infectious disease, somebody from hospital epidemiology, somebody from  employee health, if the two of them aren't the same, and the infected healthcare worker's own personal physician or treating physician for that, convene a panel, put your heads  together. You usually end up getting the hospital lawyers involved in this as well, et cetera, et cetera. And you can kind of imagine where this is going.  It's generally for people who are doing procedures that they can potentially expose people. You don't worry about psychiatrists doing it.  Most pediatricians are okay, et cetera, et cetera. It's basically surgeons, OBGYNs, and some other proceduralists, possibly like radiologists or cardiologists.  That's really a long answer to your question, but all of that to say is that there is no specific from the center guidance for work restrictions for positive hep B antigens.  And because the CDC was rather indeterminate about it, then it's become a state-by-state thing, which leaves you sort of needing to familiarize yourself with what your state  says, but that can't show up on the boards because we can't give 50 versions plus for the boards there.  So all I think you really need to know is that the CDC says that hospitals can put underlining  can, or putting it in quotation marks, exclude positive workers who perform procedures which may expose their patients. Hopefully that helped there.  Give me a thumbs up or something there. Okay, great. Anybody else? All right. Until we all say good night, except to the people on the West Coast. All right, good.  I think we'll end it for there, and you'll see Dr. Liddell and drug testing and CDL exams read up on those, watch the slides, and give her a bunch of questions for you there. Okay.  Thanks, everyone. See you later. Thank you, Dr. Meyer. Thanks, Veronese. No problem. Have a good night. Thank you.

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