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Video transcript

I'm Charles prober and I'm Morgan theis and in this video we're going to talk about pulmonary disease caused by tuberculosis and the reason we're dedicating a full-on video to pulmonary disease is that pulmonary disease is the most common form of clinical tuberculosis it represents somewhere between 60 and 80 percent of all clinical disease attributable to tuberculosis worldwide so it's way important okay so with pulmonary disease as with any form of tuberculosis disease may result either from a primary infection that is the first time the host is seeing the infection or it may result and it's called primary or it may be secondary which results from reactivation of dormant infection or sometimes from infection from a second source in a person who had a prior infection so it's or their second experience with tuberculosis and the distinction between these two is that with primary tuberculosis pneumonia following primary tuberculosis or pulmonary disease following primary tuberculosis is more common amongst children than a month than adults so children are more likely to manifest pulmonary disease with their primary infection and then the other contrasting element is that with primary tuberculosis the part of the lung which is involved is usually the lower lobes or the middle lobes so and that's contrasted from secondary tuberculosis where the part of the lung that's involved is usually the upper lobes it is said that this different result difference results from the higher oxygen tension in the upper lobes which I think facilitates reactivation but I'm not sure about the mechanism but nonetheless it is an assay Association which has stood the test of from a clinical standpoint the disease caused by tuberculosis the can can be the same whether it's resulting from a primary infection or from a secondary infection and the disease can be along an entire spectrum at one end of the spectrum is mild disease with a minimal amount of symptoms attributable to the infection and at the other extreme it can be very severe with progressive lung damage severe disability even leading to death and not only is there differences along that clinical spectrum but in parallel there are radiographic differences along a spectrum so in some occasions pulmonary disease is associated with a small infiltrate a small abnormality on the chest x-ray whereas at other times the disease may be widespread throughout both lungs and may take on a cavity reappearance which results from lung parenchymal destruction so really a cross a broad spectrum okay so with either primary or secondary pulmonary TB you can be anywhere on the spectrum exactly okay the other thing that I would say about pulmonary tuberculosis is if it is not recognized and not treated or back in the day where there was no anti tuberculous therapy the clinical course of disease a so-called natural history that is what happens if you don't treat it was divided sort of 1/3 1/3 and 1/3 1/3 of patients went on to die of their untreated pulmonary disease one third and that and that death could often be quite rapid and was called back in the day galloping consumption consuming the person's life and that's about a third a second third the patients would actually spontaneously remit they would better their signs and symptoms would go away and they would then be well and then the final third would have progressive lung involvement not galloping but more slow and this was often referred to as consumption without the word galloping in front of it so that would be the natural history of tuberculosis only seems like they should just call it the natural course instead of a natural history but there you go I think that that's a good point now when you see somebody who may be infected with tuberculosis they often have in addition to their pulmonary signs and symptoms they have other nonspecific signs and symptoms so this person who's lying in bed and you can see first of all the person appears to be quite thin and in fact weight loss is very common as a nonspecific finding of any chronic illness but in this context tuberculosis other common so-called systemic symptoms associated with tuberculosis are fevers and the fevers may go on for a long period of time days to weeks to months the fevers may be associated with sweating a net sweating often is most prominent at nighttime I'm not sure why but that's so-called night sweats and this combination of course makes somebody just feel generally unwell they have so-called malaise they don't want to eat so they're anorexic and that can take contributes to the weight loss so these are the sort of systemic symptoms that may accompany any kind of tuberculous infection including lung disease and then there are some signs in addition to the signs you will get because you have pneumonia so the clinical signs associated with pneumonia or the clinical signs associated with progressive pulmonary symptoms things like cough shortness of breath inability to breathe well especially when laying down at nighttime in addition to those findings there are some other nonspecific things that you should keep in mind when you're contemplating TB is a diagnosis and they're shown in the pictures a one picture the bottom picture is of the legs of a young individual who has tuberculosis and it shows these elevated red nodules red erythema and nodular nodosum and this is referred to as erythema nodosum it is not specific to tuberculosis it can occur in other diseases including some fungal infections like that caused by coccidioidomycosis and including streptococcal infections but it also is associated with tuberculosis and the upper picture of course is an eye and this is shown showing a particular form of conjunctivitis so redness of the eye and that is referred to as Fleck to linear conjunctivitis and that is something which is associated with tuberculosis as well and I wouldn't worry too much about spelling it because it's kind of difficult to spell all right well morgan is demonstrating ly oh i see t e n UL AR fleck the linear rectilinear conjunctivitis so these are some of the signs and symptoms that may be associated with tuberculosis in general and pulmonary TB which is the predominant form of clinical disease okay the final thing we'd like to spend a few moments talking about because it's at least in the chest cavity is plural tuberculosis so this is a little bit distinct from pulmonary tuberculosis of course a pleural membrane is that which surrounds the lung and pleural disease caused by tuberculosis can result from one of two in one of two ways one is that it may be associated with the first infection primary infection and it is said that it can be due to hypersensitivity so sort of an in new reaction of the body to the infection and in the other way that it can result either from primary disease or or I think with recurrent disease secondary disease as well is as a result of contiguous spreads so direct spread of the infection from the lungs into the pleural space the one of the distinguishing features of pleural tuberculosis compared to other forms of pleural infection is that the fusions may really be quite large the one that you've drawn showing it in the lower part of the left lung is a modest-sized pleural effusion but sometimes it can be even larger than that and extend along the whole side of the pleural space and a large pleural effusion when you see that you should think of tuberculosis as sort of one cause pleural effusions result in an extension of the pulmonary symptoms you can imagine because they're squeezing down the lungs that the person is short of breath if you percuss their chest on physical examination it sounds dull because there's not air that you're percussing but rather the solid pleural fluid and when you listen to their chest they may have decreased breath sounds because you're not hearing the lung as clearly because the pleural fluid is in between the stethoscope and the lung the best way to figure out which causing a pleural effusion in general and for tuberculosis specifically is to sample the pleural fluid to do a pleural synthesis pleural tap and when you do that the typical findings are that the fluid appears straw in color so yellowish in color it typically has a very high protein concentration a low to normal glucose concentration and white cells that number between five hundred and a few thousand is that higher low and that's high there should be no white cells in the pleural space it should be no pleural fluid but so five hundred to a few thousand with a bacterial effusion it may be a much higher white than that but with TB it's in that range you can try to visualize the TV in the pleural fluid by doing a TV specific stain such as a Zeile Nielsen stain or Zn stain so it's z IE h l + e e LS en stain and that's actually looking for the tuberculosis bacteria right okay the zeal Nielsen stain is positive somewhere between ten and twenty five percent of the time when TB is actually there so it's not very sensitive culturing the fluid is more sensitive it takes a longer time can take up to four to six weeks to culture and it has a sensitivity in the range of 25 to 75 percent and actually the best sensitivity and a test therefore that you should do if you think that this effusion represents tuberculosis is to biopsy the pleura itself and a pleural biopsy as a yield of about 80 percent so if you think somebody's got pleural TB with an effusion pleural biopsy certainly should be done