Tympanometry: What it does, why & how to use it, and what the results mean. This self-paced module will take around 20 minutes to work through.
Created by Australian Hearing June 2016
Audiologists would not choose to work without tympanometry. It’s a standard component of our hearing health test battery. But is it useful for primary health staf, and how DO you use it? This module is in four sections:
WHAT is tympanometry? WHY use tympanometry? HOW to use a tympanometer? WHAT do the results mean?
An observation from a Western Sydney GP involved in a study of effectiveness and acceptability of tympanometry in the primary health setting.
WHAT is tympanometry Tympanometry is a way of measuring how the outer and middle ear is functioning. It’s measured simply and quickly using a tympanometer. A tympanometer measures the volume of the ear canal and how flexible the ear drum and middle ear is. Combined with otoscopy, it can help us answer questions like… • Does this child still have glue ear? • What’s going on behind that wax? • Is that grommet open or blocked? …and informs treatment, management and referral decisions.
WHY use tympanometry 1.
Use it to improve confidence in your understanding of what is going on behind the ear drum.
2.
Use it when otoscopy provides no or limited information because: • Wax is blocking your view • The ear canal is narrow or bendy
3.
Use it when you reach the limits of what can be achieved with otoscopy alone: • Is a grommet is open or blocked? • What’s happening behind the wax?
4.
Use it because a test battery provides greater accuracy than reliance on a single measure.
WHY use tympanometry
This recent study with GPs in urban practices showed that having access to tympanometry results changed their diagnoses and management plans.
WHEN NOT to use tympanometry 1.
When the child’s ear is discharging.
2.
When you suspect a perforation has recently healed.
HOW to use a tympanometer Very easy. Each machine is slightly different, but they all work in similar ways. Practice on yourself or ask someone to come and practice with you. Find the instructions, or switch it on and follow the on-screen instructions. Find ear tips and place nearby. Find the interpretation guide. If you can’t, we have one, on our website.
HOW to use a tympanometer In the appointment, show and explain to the child and family. ‘Let’s see how much your ear drum bounces’ If old enough, involve the child: they could hold the machine or switch it on, help put on their ear tip. Show them it’s not sharp. Select the ear tip: small enough that it slightly enters the ear canal, but big enough that it blocks the whole entrance. Tell them what you’re going to do, like: ‘Let’s pop this in your ear. We’ll see if we can draw a picture. It buzzes, and some air goes in and out’
HOW to use a tympanometer Use the buttons to navigate to the beginning of the test, for the ear to be tested (right/left). To put in the child’s ear: •As with otoscopy: pull the child’s pinna up and back firmly, to straighten the ear canal. •Imagine where the drum is and point it in that direction. •Push the tympanometer tip firmly against the child’s ear canal opening:
HOW to use a tympanometer Watch the screen, it will tell you when you have an air seal. Once the machine has air-tight seal it will run the test automatically. If you don’t have an air seal, rotate the tympanometer slowly, aiming to point better towards the ear drum. Stop when you have a seal, and keep the tympanometer still. If you don’t get a clear result, repeat. We often do up to three times and make a decision after that. Note the results: ‘Type’ and ear canal volume in cubic centimetres, and move to the other ear.
WHAT the results mean There are two key pieces of information to note on the results screen:
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1. What shape is the trace, and where is it in relation to the box: is there a peak and does it fall within or outside the box?
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2. What is the ear canal volume, in cubic centimetres (cc)
WHAT the results mean
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A trace that indicates normal ear drum and middle ear movement is shaped like a mountain and the peak falls within the box. A trace that indicates negative middle ear air pressure has a peak that falls to the left of the box. A trace that indicates lack of movement in the middle ear system is flat.
Brain
WHAT the results mean Here is the ear Hearing nerves Middle ear and ossicles Pinna Ear canal Ear drum
Cochlea
Eustachian tube
Nose and throat
Obviously, not to scale.
WHAT the results mean
The middle ear should be filled with air. air same
same
The air pressure in the middle ear should be the same as the air pressure outside. Air gets into and out of the middle ear via the eustachian tube.
WHAT the results mean
hmmmmmm
When you do tympanometry, the machine pumps a small amount of air into the ear canal and draws it back out again. It also sends a soft humming signal into the ear, and measures what bounces back. The machine puts these pieces of information together and works out ear canal volume and middle ear movement.
WHAT the results mean
Ear canal volume is the space beyond the tip of the tympanometer. If the ear drum is whole (no hole!), the space will finish at the ear drum. If the ear drum has a hole, the space will extend into the middle ear. Average range of normal ear canal volume for children is 0.2 to 1.0cc When the machine measures past the ear drum into the middle ear, average volume range is greater than 1.0cc. You need to know this to interpret t
WHAT the results mean Here’s a middle ear with normal air pressure. The ear drum will move backwards and forwards freely. When you 2 do tympanome 1 try, the 0 result will look like this, with This is the pattern that theshows peak in normal middle ear movement the box: and air pressure. This is a
Type A.
WHAT the results mean Test your knowledge1: What does this shape indicate?
Answer: 2
Normal ear drum and middle ear movement. 1
0
WHAT the results mean Test your knowledge 2: What is the normal volume range of a child’s ear canal, in cubic centimetres? Answer: 2
0.2-1.0 cc 1
0
WHAT the results mean Let’s say the child has picked up the germs that cause ear infection Remember that the walls of the middle ear are lined with moist mucous membrane. The air flow in and out of the middle ear helps evaporate excess moisture from the middle ear space.
But the Eustachian tube has now inflamed in response to the germs and has blocked. Air cannot enter or leave the middle e
WHAT the results mean However, the mucous membranes lining the ear still need to absorb air to function. They continue to do this, even though there is no fresh air coming up the eustachian tube. As the mucous membranes absorb the air, the air pressure in the middle ear becomes negative: a vacuum. The greater the 2 vacuum, the further the 1 peak moves to the left. 0 This is a Type
C.
WHAT the results mean If the Eustachian tube remains blocked, moisture from the mucous membranes starts to fill the middle ear.
WHAT the results mean This is fluid-filled middle ear; either acute otitis media or glue ear. Because the middle ear is filled with fluid, the ear drum cannot move freely backwards and forwards. If you did tympanometry now, what would the trace look like: peaked or flat? Flat, which 2 shows no movement of 1 the drum and middle ear 0 system in response to the tympanometer. This is a
Type
WHAT the results mean This is the point at which ear canal volume becomes relevant. A Type B result indicates no movement of the drum and middle ear system in response to the tympanometer. But fluid in the middle ear is not the only condition that causes this. The other conditions are also clinically useful to recognise. Let’s look at these‌
WHAT the results mean Complete wax blockage of the canal also gives a Type B result. Remember Type B means no movement of the drum and middle Wax does not move in response ear system. to the air being pumped in and out of the ear canal. So, how can you tell the diference between a wax blockage and fluid-filled middle ear? 1. You would have a good idea from otoscopy (although not if you couldn’t get a good view) 2. Look at the canal volume‌
WHAT the results mean Remember that normal ear canal volume is 0.2-1.0cc for children.
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On the graph, that’s here:
But if you have a wax blockage, where will the machine measure to‌? Yes: only up to the wax. So, that will be a lower canal volume than normal: less than 0.2cc.
WHAT the results mean So, to recap, Type B with low canal volume (<0.2cc) suggests wax blockage. 2
1
0
WHAT the results mean Type B with normal canal volume (0.2-1.0cc) suggests fluid-filled middle ear. 2
1
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WHAT the results mean And Type B with high canal volume (>1.0cc) suggests a perforated ear drum. 2
1
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Q. In a child with grommets, what would a Type B, high volume result mean? A. The grommet was open and ventilating the middle ear well.
WHAT the results mean Test your knowledge 3:
A child with a lot of wax gets this result:
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1. What Type is this? 2. What does this indicate?
Answer: 1. Type B low volume 2. It indicates wax blocking the ear canal.
WHAT the results mean Test your knowledge 4:
A child with a lot of wax in their ear gets
2
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1. What Type is this? 2. What does this indicate?
Answer: 1. Type A 2. It indicates that the wax is NOT blocking the ear canal, and behind the wax the middle ear is working well.
WHAT the results mean Test your knowledge 5:
A child with a lot of wax in their ear gets
2
1
0
1. What Type is this? 2. What does this indicate?
Answer: 1. Type B, high volume 2. It indicates that the wax is NOT blocking the ear canal, and behind the wax there is a perforated ear drum.
WHAT the results mean Test your knowledge 6: A tricky one. You see a child with grommets. You do tympanometry and get this: 1. What Type 2 is this? 1
0
2. What does this indicate?
Answer: 1. Type B, high volume 2. It indicates that the grommet is open and working well ď &#x160;
WHAT the results mean Test your knowledge 7: OK, trickier. You see a child with grommets. You do tympanometry and get this: 1. What Type 2 is this? 1
0
2. What does this indicate?
Answer: 1. Type B, normal volume 2. It indicates that the grommet is blocked, and the middle ear is filled with fluid again.
WHAT the results mean Test your knowledge 8: Last one. You see a child with a cold and get this: 2
1
0
1. What Type is this? 2. What does this indicate?
Answer: 1. Type C, normal volume 2. It indicates eustachian tube blockage & negative middle ear air pressure. This may transition to fluid-filled middle ear, or may
To recap: Use tympanometry routinely to improve confidence, diagnostic accuracy and treatment & management decisions in relation to middle ear state. It assists you to make referral decisions: For example, it can help you mark the point at which ear disease has persisted beyond the threemonth post-commencement of treatment point and diagnostic audiometry is now required to measure impact on hearing. Itâ&#x20AC;&#x2122;s fast and easy. It gives you information you could not have learned from otoscopy alone.
For help: The interpretation guide is available on our website: https://www.hearing.co m.au/category/hearings olutions/aboriginal-andtorres-strait-islanderservices/
For help: Our fact sheet Who, When and How to refer to Australian Hearing for Health Services in Aboriginal & Torres Strait Islander communities will assist with referral to Australian Hearing. For instance: â&#x20AC;&#x2DC;When a child has middle ear disease, follow treatment and referral pathways in the Guidelines*. When ear disease lasts longer than three months, arrange a diagnostic hearing test or Sound Scouts to check impact on hearing. If results show average hearing level worse than 35dBHL better ear, or Sound Scouts score lower than 44, refer to Australian Hearing. See over for more information on Sound Scouts and pathways.â&#x20AC;&#x2122;
Ask the visiting Australian Hearing Audiologist to freshen up your tympanometry skills.
For help:
Ask the visiting Australian Hearing or other Audiologist to freshen up your tympanometry skills with face to face training for your staff.
Has this training met your needs? Thanks very much for taking part in this training. Could you please complete this six-question survey? http://www.surveygizmo.com/s3/2881820/Tympanometry-self-paced-training
For all enquiries about this training, please email samantha.harkus@hearing.com.au or call 0412 799 387.