[Music] hi I'm Ted venoma let's talk about tonometry tonometry is a test that should be used in combination with the typical audiogram that tests pure tone hearing sensitivity tonometry is really a test of middle ear status tonometry should be used when a conductive hearing loss is seen in an audiogram when there's a difference between air conduction hearing levels or air conduction sensitivity hearing through headphones that is compared to hearing through the bone and as we said during the audiometry talk reading the audiogram if there's a difference between hearing sensitivity between the way you hear through headphones as opposed to the way you hear through the bone that means there's a problem with the outer or middle ear and we call this an airbone Gap when there's a difference in hearing sensitivity from Air conduction compared to bone conduction we should use tonometry to back this up the nice thing of tonometry is it's a non-behavioral test it's quick it's often done on children pedi patricians understand and understand it and have used it for years with kids looking for otitis media and let's go to slide number two here and we'll just see how it works when air pressure is equal on both sides of the tanic membrane that creates the least stiffness of the middle ear and the most compliance in plain English when air pressure is Even Steven between the outer ear connect now and the middle ear space when the air pressure is even on both sides of the eardrum the middle ear is most efficient at passing sound through it's all about air pressure being equal on both sides of the drum when what we do during tonometry is we emit a tone at a steady intensity and the tone comes out of this probe we make an airtight seal you'll notice there's three three holes in this probe one is a little speaker that emits a tone the second one is a microphone that measures what sound is bouncing back off the eardrum and the third little hole is an air pressure changer it changes air pressure from positive to normal to negative and so you're making positive to a vacuum and so the probe speaker emits out a tone the probe mic picks up whatever bounces back off the eardrum while the air pressure changes from positive to negative and we want to find out at what air pressure does the least amount of sound bounce back that is at what air pressure does most sound go through because remember it's all about the air pressure being even on both sides of the drum if this happens if most sound goes through the ear canal or through the eard drum into the middle ear if most sound goes through that way when air pressure in the outer ear canal is at room air pressure this must mean therefore that the air pressure here is room air pressure so therefore temp tonometry measures in the outer ear canal can tell the status of air pressure in the middle ear it's amazing it's it's it's a really interesting Quick Test takes about 5 minutes maximum and that's why the test is is also of value it's really a test of middle ear efficiency if the air pressure is Even Steven on both sides of the drum most sound will go through and if that most sound goes through when this air pressure is at room air pressure then we know air pressure in the middle ear space is room air pressure here's what the temp panogram looks like kind of like a pup tent this axis here shows negative room air pressure and positive air pressure the vertical axis shows middle ear compliance remember the middle ear is a stiffness dominated system there's very little mass in the middle ear the middle ear oses are the smallest bones in the body the middle ear is quite a stiff system so we're use we're trying to find out at what air pressure pressure is the is the is the middle ear most and least stiff and we tell that by the amount of sound that's bouncing back off the drum so we begin at positive air pressure in the ear canal positive air pressure with that airtight seal with that probe in the ear canal and when most sound bounces back off the drum because now you're making that middle year really stiff you're you're you're adding air pressure even it's a stiff system already but now you're adding air pressure to it well then almost all the sound is bouncing back off the drum and so we've got low compliance positive air pressure low compliance meaning all the sound is bouncing back when we change the air pressure in the outer ear canal to room air pressure least sound bounces back remember the ear middle ear is most efficient when pressure is Even Steven on both sides of the drum well now least amount of sound is bouncing back and you have highest compliance the middle ear is least stiff when we continue now to make the air pressure negative once again we're returning to an unhappy status we're stiffening that middle ear system again even more and we have low compliance once again all the sound is bouncing back off the drum and clients can literally hear this when you're getting a temp panogram done you'll hear [Music] you literally hear it the test is quick the client can kind of feel those little bit bits of air pressure changes always remember tonometry is not like pneumatic oscopy which actually moves the drum we're not trying to find out how much the eard drum Wiggles that's really an incorrect conception of tonometry tonometry is a test of middle ear efficiency measuring and comparing the amounts of sound that bounce back off the drum as we change ear air pressure amounts of sound bouncing back off the drum as we change air pressure let's move to a picture of otitis media and tonometry here's a normal temp panogram often called a type A you can see its peak is over normal room air pressure that's Happy Land otitus media now enters the picture early otitis media negative middle ear pressure eard drum is retracted inward so guess what we've got to use negative air pressure in the outer ear canal so that the air pressure in the outer ear canal is Even Steven with the negative pressure within the middle ear space so now we've got to use negative air pressure in order for least amount of sound to bounce back for the middle ear to be most compliant least STI and this is called a type c temp panogram it's it has a peak like the type A but it's over negative air pressure because we needed negative air pressure in the outer ear canal to match the negative air pressure behind the eard drum as the otitis media advances now the middle space begins to become filled with serous fluid and then purulent otitis media develops you've got a fluid filled middle ear and an infected middle ear and now the type C temp panogram begins to become very rounded and finally you've got a flat temp panogram a type B showing no peak whatsoever because hey changes of air pressure in the outer ear canal are no competition for pus behind the drum no amount of changes of air pressure in the outer ear canal is going to counteract the fact that now the middle your space is filled with fluid so a type A goes to a type c with early otitis media and then transitions to a type B showing Advanced otitis media and again o tonometry is done so quickly it's unbelievable that's not the only thing it can talk about this last slide shows temp panogram associated with normal hearing and otosclerosis as we know otosclerosis is a soft porous growth of bone around the foot plate of the stapes in the ular chain otosclerosis has nothing to do with air pressure anomalies behind the eardrum like otitis media otosclerosis is an artificial stiffening of the whole middle ear system as such it's temp panogram will still have a peak much like the type a normal temp panogram does however due to the stiffness that the that the otosclerosis causes the peak will be shallower than normal so you will have less compliance it'll be more stiff and hence the temp panogram is still called a type A because it's Peak is over regular room air pressure but it's stiffer than normal it's called an as so when one Fell Swoop tonometry can talk about stages of otitis media it can back up findings of otosclerosis it's a useful quick non non-behavioral type of test we hope you've enjoyed this little vignette on tonometry thanks for listening [Music]