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Video transcript

now bronchiolitis is a common respiratory tract infection in young children but what exactly do I mean by this and how does it different from a common cold well in order to discover this let's break down the word and bronchiolitis can be broken down into two parts bronchial and itís now bronchial refers to an anatomic location in the lungs so describe this let me just bring in a cartoon of the respiratory tract up here in blue is the oral and nasal cavity in the upper part of the throat that's our upper respiratory tract and then as you go down you encounter the Airways in the lung tissue it's often so this is the lower part of the respiratory tract the lower respiratory tract and the bronchioles as you go down through the trachea here into the bronchi these kind of ending branches out here these are bronchioles so you can imagine that bronchiolitis has something to do with the bronchioles but what is itis mean well generally speaking in medicine anytime you see a word that ends in itis it refers to inflammation now what do I mean by inflammation in order to describe information let me use an example here imagine this guy over here hits his head now what's going to happen over time well the area of his head underneath where he got hit it's going to kind of bulge up and you're going to get a little swelling so you have some swelling and it's going to turn red and the area is going to become painful and even a little bit warm and those are the characteristics of inflammation pain tenderness warmth and redness and what inflammation is is it's the body's reaction to injury so in bronchiolitis you get that same kind of inflammation but in the bronchioles let me show you that all right so here we have a zoomed in image of the bronchioles here so in bronchiolitis you're going to have inflammation of these so we now know that bronchiolitis is inflammation of the bronchioles but what causes bronchitis bronchiolitis is a viral infection and the most common virus that causes bronchiolitis is known as respiratory syncytial virus but that's a little bit difficult to say so we're just going to call it RSV now RSV causes bronchial by entering the respiratory tract and it can enter the respiratory tract either from someone who's infected who coughs and it costs the virus out into the air and then this guy over here will in inhale it or that virus can be sitting on something and then this person may touch it with their hand and get the virus on their hand then touch their mouth and that is the way they get the virus into their respiratory tract and the first part of bronchiolitis is actually an infection and inflammation of the upper airway so even though bronchiolitis is inflammation of the bronchioles it starts out as infection in inflammation of the upper airway and this makes sense because the in first signs and symptoms of bronchiolitis are actually a runny nose and nasal congestion now at this point if you think bronchiolitis just kind of looks like the common cold you'd be right because the common cold is a viral infection of this upper airway just like what we just happen but in bronchiolitis the virus actually makes its way down from the upper respiratory tract down into the bronchioles and it causes the infection down here and so that's what differentiates bronchiolitis from the common cold and it's this infection and subsequent inflammation of the bronchioles that produces a few more symptoms that are a little more characteristic of bronchiolitis and these symptoms are cough and wheezing now a cough can occur in an upper airway infection because you have some secretions from the infection that fall down the airway and that irritates the airway so you cough it up but wheezing only happens if you have disease in this lower airway so wheezing is a very important symptom for bronchiolitis because it lets you know that something's going on in the lower respiratory tract well these symptoms don't really seem that bad so what's the big deal with bronchiolitis the big deal is that sometimes in bronchiolitis the child's lungs have a hard time getting oxygen and that can cause some problems so let me show you how that happens now imagine that this part right here is where oxygen in the air is exchanged during the body and in order to get there the air is going to have to travel through the bronchioles but in bronchiolitis sometimes as inflammation gets so bad that these bronchioles are blocked so the air can't get into the lung tissue itself and you have no oxygen there and if the oxygen in the air can't reach the lung tissue it can't get into the blood and this is known as hypoxemia and the child's body does two things to try and compensate for this low oxygen and that's the increase increase his or her heart rate and increase his or her breathing rate and this increase in heart rate and breathing takes up a lot of energy and over time the child can get kind of tired and gets a little bit sleepy and sleepiness is assigned and bronchiolitis that the child is getting really sick so anytime any of these symptoms like increase heart rate or a child just having a hard time breathing or becomes really sleepy any time those are present it's probably time to call the doctor because the child may require treatment in the hospital so now that we know that bronchiolitis is inflammation of the bronchioles it's caused by viral infection what are some of the risk factors for developing bronchiolitis well since bronchiolitis is a viral infection the most common risk factors have to do with being in contact with the virus so being around other children that are sick is a big risk factors I'm going to label that as sick contacts and another risk factor that has to do with exposure to the virus is season an RSV is most common in the fall and winter months now this is a little misleading because the reason we think RSV is most common in the fall and winter is because children tend to be inside and in kind of more closed spaces so they're in closer contact with the sick contacts so this may actually be just a representation of sick contacts but it's so it's good to remember that children are most commonly infected with RSV in the fall and winter but what are some of the other risk factors well since the RSV infection that leads to bronchiolitis first starts in this upper airway if a child's immune system isn't working properly that infection is more likely to start here so I'm going to put poor immune system there's also some risk factors that have to do more with the lower respiratory tract the first one I want to talk about is age because bronchiolitis is most common in children under the age of two years now the next one is prematurity so any child who is born premature especially less than 35 weeks gestation their lungs just aren't quite as developed as children who were born mature and part of this is that their Airways are just narrower and if you imagine that this inflammation is occurring in the airways and the bronchioles that's going to decrease the size of the airway and air is going to have a harder time getting through so if you have a narrower airway to start with less inflammation causes this blockage of airflow and result into hypoxemia like we talked about earlier and another risk factor that affects the lower reservoir track is pre-existing lung disease and the last one I want to mention is smoke exposure and smoke exposure causes small amounts of injury to the lower Airways and lower respiratory tract here so children exposed to smoke will already have a little bit of inflammation and this pre-existing low level of inflammation due to secondhand smoke exposure makes them more susceptible to infection of this area so to recap brought bronchiolitis is a very common respiratory tract infection in children especially under the age of two years old and if you can remember the breakdown the word you can remember what's going on remember it's inflammation or itis of the bronchioles which are the end part of the airway before we get to the lung tissue and this inflammation is caused by viral infection most commonly RSV it presents with runny nose nasal congestion cough and wheezing