hi I'm dr. Sandra Adams and I'm a pulmonologist I'm going to describe an easy way to demonstrate tactile fremitus in the normal lung pneumonia which is consolidation pleural effusions which is fluid between the two linings of the pleura including the visceral and parietal pleura and a pneumothorax which is air between the visceral and the parietal pleura now fremitus 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 in this straw to demonstrate how to feel tactile fremitus in a simulated environment in the normal lung in pneumonia or consolidation in pleural effusions and in a pneumothorax the first situation is going to be our baseline in which the plastic of the cup represents the visceral and parietal pleura 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 bronchus by humming into the straw the vibration travels down the straw which is the bronchus through the air in the cup like the air in the lungs through the plastic which is the pleura in the chest wall which you can feel with the bony part of your hand so let me a demonstrator 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 fremitus 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 fremitus 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 pleura the plastic of the outer cup represents the parietal pleura and chest wall so what does this represent in clinical practice fluid between the pleural surfaces is exactly a pleural effusion so now we're going to hum through the straw into the empty cup and feel the vibration below the level of the liquid and the outer cup hmm what do you feel well I don't feel any vibration or at least it's markedly 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 bronchus and the liquid the effusion the sound slows way down when the straw hits the visceral pleura the inside cup then the sound vibration has to go through the cushion of fluid that's not directly connected to the straw bronchus which blunts the vibration therefore in pleural effusions tactile fremitus is markedly decreased or absent below the level of the fluid depending on the size of the effusion now what we're gonna do is take the two empty cups one that's smaller then the other one do not let the cups touch again the smaller Cup represents the visceral pleura the larger cup represents the parietal pleura and chest wall so what does this represent when there's error between the visceral and parietal pleural surfaces what is that yes this is a pneumothorax so we're gonna hum into the straw again and the smaller Cup and feel the vibration on the outer cup so what do you feel assuming the cups do not touch what do you feel again nearly no vibration or at least markedly decreased why well again the vibration slows way down when the straw hits the visceral pleura 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 pneumothorax tactile fremitus is markedly decreased or absent in the area of the air depending on the size of the pneumothorax therefore in consolidation tactile fremitus 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 fremitus is decreased in a pleural effusion and in pneumothorax because there's no connection between the bronchi in the fluid and the infusion so the fluid in the effusion and the air in the pneumothorax act as a buffer to decrease or completely obliterate the vibration to your hands