Hi, I'm Dr. Sandra Adams and I'm a pulmonologist. I'm going to describe an easy way to demonstrate tactile femus in the normal lung, pneumonia which is consolidation, plural eusions which is fluid between the two linings of the plura including the visceral and parietal plura and enumothorax which is air between the visceral and the parietal plura. Now fmitus is a vibration felt on the patient's chest or back during low frequency vocalization. Oftentimes we ask patients to say something like 99 and feel the vibration over the back of their thoracic cavity symmetrically with the bony surfaces of our hands. You can either feel with this part of your hand or with the bones here in the palm of your hand. I'm going to be explaining with these cups and this straw to demonstrate how to feel tactile femus in a simulated environment in the normal lung in pneumonia or consolidation in plural eusions and in a numothorax. The first situation is going to be our baseline in which the plastic of the cup represents the visceral and parietal plura as well as the chest wall. The air inside the cup represents the air inside the lung and the straw represents an air tube also called a bronus. By humming into the straw, the vibration travels down the straw which is the broncus through the air in the cup like the air in the lungs through the plastic which is the plura in the chest wall which you can feel with the bony part of your hand. So let me demonstrate. [Music] M. Okay. So, that's the baseline and you can feel the vibration. Now, you're going to take a cup with water in the bottom of the fourth of the cup. And this water represents consolidation like pneumonia, which is pus inside the lungs. You're going to place your hand under the level of the water at the bottom of the cup and hum into the straw again. So, what do you feel now? compared to your baseline lung. What do you think? Well, you can feel the vibration much more easily. Therefore, feminis is increased in pneumonia. Now, why does the vibration feel stronger when there's liquid or pneumonia inside the cup or the lung? Why is that? That's right. Sound and vibration travel more easily through liquid than through air. Therefore, the sound travels down the straw initially through the air but then hits the liquid and the vibration becomes much stronger. It kind of takes off when you feel the outside of the cup. So, tactile femus is increased with consolidation which is fluid or pus in one area of the lung like in pneumonia. Now, we're going to take the smaller empty cup and place it in the liquid of the larger cup. The plastic of the smaller cup now represents the visceral plura. The plastic of the outer cup represents the parietal plura and chest wall. So what does this represent in clinical practice? Fluid between the plural surfaces is exactly a plural eusion. So now we're going to hum through the straw into the empty cup and feel the vibration below the level of the liquid in the outer cup. H what do you feel? Well, I don't feel any vibration or at least it's marketkedly decreased. But why? There's fluid in there. Didn't we say that sound and vibration travel more easily through liquid than through air? Well, the key is that there's no connection between the straw, the broncus, and the liquid, the eusion. The sound slows way down when the straw hits the visceral plura, the inside cup. Then the sound vibration has to go through the cushion of fluid that's not directly connected to the straw or broncus which blunts the vibration. Therefore, in plural eusions, tactile framitus is markedly decreased or absent below the level of the fluid depending on the size of the eusion. Now, what we're going to do is take the two empty cups, one that's smaller than the other one. Do not let the cups touch. Again, the smaller cup represents the visceral plura. The larger cup represents the parietal plura and chest wall. So, what does this represent when there's air between the visceral and parietal plural surfaces? What is that? Yes, this is a pumothorax. So, we're going to hum into the straw again in the smaller cup and feel the vibration on the outer cup. [Music] So, what do you feel? Assuming the cups do not touch, what do you feel again? Nearly no vibration or at least marketkedly decreased. Why? Well, again, the vibration slows way down when the straw hits the visceral plura, the inside cup. And then the sound vibration has to go through that cushion of air, which is an even worse conductor than the fluid. So again there's a cushion that blunts or obliterates the vibration. Therefore in a numoththorax tactile framitus is markedly decreased or absent in the area of the air depending on the size of the pumothorax. Therefore in consolidation tactile primitus is increased because the bronchi are conducting the vibration from our larynx through the lung. But when the vibration hits the pus or fluid in the consolidated lung like with pneumonia the vibration takes off increases and you can feel it very easily on the patient's back. In contrast the tactile femus is decreased in a plural eusion and a pumothorax because there's no connection between the bronchi in the fluid and the infusion. So the fluid and the eusion and the air in the pumothorax act as a buffer to decrease or completely obliterate the vibration to your hands.