MI 34 and MI 34h Operating Instructions Rev C Aug 2005

Operating Instructions MI 34, MI 34h Table of Contents

Page

1.

Introduction

2

2.

Description

3

3.

Getting started

5

4.

How to create a Tympanogram

13

5.

How to create a Tympanogram with high probe tone (MI 34h)

18

6.

How to measure the Stapedius reflex

19

7.

Reflex decay test operation

24

8.

Eustachian tube test operation

26

9.

Interpreting test results

28

10. How to test children

31

11. Additional Reading

32

12. Individual setup of the MI 34

33

13. Care and maintenance of the instrument

40

14. How to change the printer paper

41

15. Warranty, maintenance and after-sales service

42

16. Safety regulations

45

17. Subjective checklist

46

18. Technical data

47

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Operating Instructions MI 34, MI 34h 1 Introduction Thank you very much for purchasing a quality product from the MAICO family. This automatic Tympanometer MI 34 is manufactured to meet all quality and safety requirements. In designing the MI 34 we placed particular importance on making it a user-friendly device, meaning its operation is simple and easy to understand. And because all functions are software controlled, upgrading later to new, extended measurement functions will be simple and inexpensive. That means that you have invested in a device that will adjust to your future needs. This user manual should make it as easy as possible for you to become familiar with the functions of the MI 34. The description of the position (e.g., 5 ) of controls, displays and connections, found again in the text, will make it easier for you to learn how to operate the MI 34. If you have problems or have ideas for further improvements, please get in touch with us. Simply call. Your MAICO team

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Operating Instructions MI 34, MI 34h 2 Description The MI 34 is an automatic instrument that is designed for tympanometric testing. Tests performed in the tympanometric testing mode measure middle ear mobility, ipsilateral acoustic reflex, contralateral reflex, reflex decay and Eustachian tube testing. Test results are displayed on the front panel LCD (liquid crystal display) screen and may be printed. The design of the MI 34 allows rapid and reliable measurements. This equipment is designed for middle ear function screening. PC-Interface: A serial RS 232C interface for data transfer to a connected computer is built in.

2.1 Tympanometry musculus stapedius

Tympanometry is the objective measurement of middle ear mobility (compliance) and pressure within the middle ear system. During the test, a low-pitched probe tone (226 Hz) is presented to the ear canal by means of the hand-held probe. This tone is used to measure the change in compliance in the middle ear system while the air pressure is varied automatically from a positive value (+200 daPa) to a negative value (-400 daPa max.).

hearing nerve

middle ear bones ear canal ear drum

cochlea

middle ear eustachian tube Figure 1 The middle ear

Maximum compliance of the middle ear system occurs when the pressure in the middle ear cavity is equal to the pressure in the external auditory canal. This is the highest peak of the curve as it is recorded on the chart. The position of the peak on the horizontal axis and on the vertical axis of the chart will provide diagnostic information regarding the function of the middle ear system. Examples of normal and abnormal tympanograms can be found in a later section of this manual. Gradient calculations are reported as the tympanogram width at half of peak compliance expressed in daPa. A “limits” box is available on both the display and printout to aid in diagnosis. Compliance is measured with respect to an equivalent volume of air, with the scientific quantity milliliter (ml). Air pressure is measured in deca-Pascals (daPa). NOTE: 1.02 mm H2O = 1.0 daPa.

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Operating Instructions MI 34, MI 34h 2.2 Acoustic reflex An acoustic reflex, or contraction of the Stapedial muscle, occurs under normal conditions when a sufficiently intense sound is presented to the auditory pathway. This contraction of the muscle causes a stiffening of the ossicular chain which changes the compliance of the middle ear system. As in tympanometry, a probe tone is used to measure this change in compliance. When the stimulus presentation and measurement are made in the same ear by means of the probe, this acoustical reflex is referred to as an ipsilateral acoustic reflex. When the stimulus presentation and measurement are made in opposite ears, the reflex is referred to as a contralateral acoustic reflex. For best results, this reflex measurement is automatically conducted at the air pressure value where the compliance peak occurred during the tympanometric test. Stimulus tones of varying intensities at 500, 1000, 2000 or 4000 Hz are presented as short bursts. If a change in compliance greater than the selected level is detected, a reflex is considered present. Because this is an extremely small compliance change, any movement of the probe during the test may produce an artifact (false response). The test result is recorded as Pass/No response, and in graphical form. If the tympanometric results display any abnormal findings, the results of the acoustic reflex testing may be inconclusive and should be interpreted with care. Theoretically, a compliance peak is necessary to observe a reflex at peak pressure.

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Operating Instructions MI 34, MI 34h 3 Getting started Your MI 34 was carefully inspected and packed for shipping. However, it is good practice to thoroughly inspect the outside of the shipping container for signs of damage. If any damage is noted, please notify the carrier immediately.

3.1 Unpacking Remove the accessories. Carefully remove the instrument from the shipping carton. Remove the instrument from the plastic bag and inspect the case for any damage. Notify the carrier immediately if any mechanical damage is noted. This will assure that a proper claim is made. Save all packing material so the claim adjuster can inspect it as well. When the adjuster has completed the inspection, notify the MAICO Special Instrument Distributor you purchased this unit from. Save all the original packing material and the shipping container so the instrument can be properly packaged if it needs to be returned for service or calibration. 3.1.1 Accessories supplied Please check that all accessories listed below are received in good condition. If any accessories are missing or damaged, immediately notify your MAICO Special Instrument Distributor. Description Hand-held probe 24-count eartips kit: (4) yellow, 7 mm (4) green, 9 mm (4) white, 11 mm (4) yellow, 13 mm (4) green, 15 mm (4) blue, 18 mm Thermal printer paper Calibration test cavity Shoulder strap Insert phone or TDH39 contra phone Operating Instructions

Part No. 570G-14 6613 6643 6644 6645 6646 6647 6648 5529 5533 58621 4796 4682 1162-0324

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Operating Instructions MI 34, MI 34h 3.2 Environmental conditions for the MI 34 The MI 34 should be operated in a quiet room. The test room must be at normal temperature, usually 15° C / 59° F to 35° C / 95° F, and the instrument should be switched on about 10 minutes before the first measurement to guarantee precise measuring results. If the device has been cooled down (e.g. during transport), please wait until it has warmed up to room temperature

3.3 Preparing the MI 34 for use 3.3.1 Connect probe and accessories C on the rear of

-

Connect the probe cable to socket the instrument.

-

Insert the plug into the socket and secure the connection by fastening the two screws of the connector.

-

Insert the pressure tube into the socket B it until it is secure on the socket.

-

Put the enclosed power cable into the power connection socket Aand then plug it into a power outlet. The instrument is now operational.

and press

Figure 2 The probe of the MI 34

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Operating Instructions MI 34, MI 34h 3.4

Getting familiar with the MI 34 3.4.1 The MI 34 front panel controls

13

1

2

3

4

5

6

7

8

9

10 11

12

Figure 3 MI 34 front panel

See the following keys: 1. Print = Printout 3. Reflex = Reflex measure off/ipsi/contra 5. Decay = Decay test key 7. Menu 9. Down = Down (cursor control) 11. Up = Up (cursor control) 13. Power = Power switch

2. L/R = Switch over left/right ear 4. Tymp = Tympanometer test key 6. ETF = Eustachian tube function test key 8. Left = Left (cursor control) 10. Right = Right (cursor control) 12. Enter = Enter

How to use the extended functions is described in chapter 9: “Individual Setup of the MI 34."

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Operating Instructions MI 34, MI 34h 3.4.2 The MI 34 rear panel connections

E B C

D C

D E

A G

Figure 4 Connectors on the rear of the MI 34

A. Power connection socket B. Probe tube connection C. Probe connection socket D. PC interface E. Contra receiver socket 3.4.3 Switch the instrument on Turn the power switch 13 on. The LCD will show the type of instrument and software version for a moment. Then the basic measuring figure appears. The MI 34 should be switched on about 10 minutes before the first measurement to guarantee precise measuring results. If the device has been cooled down (e.g. during transport), please wait until it has warmed up to room temperature.

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Operating Instructions MI 34, MI 34h 3.4.4 The display of the MI 34 The test result is shown during the measurement on the LCD. The measurements are saved automatically and can be printed out in a fast and quiet way with the integrated printer. In figure 5 the initial empty measurement screen is shown. The measurement screen shows actual settings, test results and the graphical display of the tympanogram and reflexes. From left to right the top line shows the type of test (impedance is shown in figure 5), the selected test ear (left or right) and the selected reflex test (ipsi, contra or tympanogram if no reflex test is selected). At the left center, the graph of the tympanogram is shown. At the right, five boxes show the status and test values.

Impedance

3

Right

Ipsi Status READY

ml

Ear Volume 2

Compliance 1

Pressure 0

-600

-300

1

2

80 500 Hz I

Gradient

300 daPa 3

80 1000 Hz I AUTO

4

80 2000 Hz I dB

80 4000 Hz I

Figure 5 The measurement screen of the MI 34

The upper box shows the actual status of the instrument: Ready - means that the instrument is ready for testing In Ear - shows that the probe is inserted in the ear Testing - means that the test is in progress Blocked - means that probe is blocked in the ear Leaking - indicates that the eartip does not have a proper seal The boxes below Status show the volume of the ear canal, the compliance, the pressure at maximum compliance and the gradient of the tympanogram when the test has been completed. The four boxes at the bottom of the screen, marked 1 to 4, show the graphical reflex curves after the test. Below each box the test level (figure 5: 80 dB), and the test frequencies (figure 5: 500 Hz, 1000 Hz, 2000 Hz and 4000 Hz) are displayed. After the frequency an “I” shows that ipsilateral testing is selected. Finally, at the very bottom in figure 5 the word Auto and 80 dB scale is shown. This means that the reflex test level will increase automatically until a reflex is found or the maximum level is reached. With the arrow keys, the test levels can be changed to a fixed level. The dB values below the boxes change accordingly. It is possible to have fixed levels from 70 dB to 100 dB or Auto.

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Operating Instructions MI 34, MI 34h 3.5 Calibrate the probe Adjust the impedance measuring instrument every day to the actual atmospheric pressure by means of the enclosed calibration volume. The calibration is very easy and takes only 20 seconds. Press the menu key 7 and the main menu (figure 6) appears on the LCD. Select the menu option Calibration with the arrow keys and press Enter. Follow the instructions on the LCD as shown in figure 7. Put the probe tip S without eartip into the hole of the test cavity labeled 0.5 ml. The text on the display will request that the probe tip be inserted for the 2 ml calibration. Put the probe tip in the 2 ml cavity. Do this again for the 5 ml volume. The MI 34 will automatically change into the tympanometry mode. The basic menu for the impedance measurement appears again and you are ready for measurements. If the error information Cavity Calibration Out of Range appears during the calibration, please check if the opening of the probe tip is clean and try to recalibrate the probe. If the error information appears again, the probe or the instrument are probably in need ot service. Contact your Maico Special Instruments distributor to get immediate help.

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Main Menu Tympanometry : Calibration : Setup :

↑ ↓ Change item ENTER Select item

Calibration Place the probe in the .5 ml cavity.

Figure 7 The calibration screen

Operating Instructions MI 34, MI 34h 3.6 Getting familiar with the probe The probe of the MI 34 is shown in figure 8. The probe head is adjustable to three angles (0°, 60° and 80°). It is adjusted by turning the locking screw T at the bottom of the probe using a coin or a screw driver. Adjust the probe head P by pulling it into the required position until it rests. After it is set to the required position tighten the fixation screw again. The probe button M can be used to select the required test ear. The color of the O control light changes accordingly to red (right ear) or blue (left D T EL C N P E R E G S ear). The color of the control light on the probe indicates your current operation. M B O D E G EL C N P Q E E R S A red control light indicates that the right ear is selected. The system is ready for Figure 8 measurements. As soon as The probe of the MI 34 you have put the probe into the auditory canal the control light turns green. Now the test is in progress. Do not change the position of the probe until the green control light goes out indicating the end of the measurement. A blue control light indicates that the left ear is selected. The system is ready for measurements. As soon as you have put the probe into the auditory canal the control light turns green. Now the test is in progress. Do not change the position of the probe until the green control light goes out indicating the end of the measurement. A yellow control light indicates an error. The kind of the error is indicated on the LCD under status: Leaking: The eartip is not sealed in the auditory canal. Change the position of the probe until the control light turns green. If you are not successful use a bigger eartip. Blocked: Indicates blockage in the probe opening. Change the position of the probe so that it points straight into the auditory canal until the control light turns green. If you are not successful, check that the probe is not blocked with ear wax. The complete probe insert can be changed by pressing the release button Q . If the probe tip is clogged, you can remove it by opening the fixation ring R . After cleaning the probe tip or attaching a new one, the tip must be fixed again by fastening the fixation ring.

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Operating Instructions MI 34, MI 34h 3.7 Choose an appropriate eartip Choose an eartip of the appropriate size from the eartip set. Put the eartip tightly on the probe tip. The probe tip should end near the end of the eartip. It should not be inserted more than about 1 mm inside the eartip or protrude out of the eartip (see figure 9). By choosing an appropriate eartip and placing it correctly on the probe you create the basic conditions for measurements without problems and mistakes. Now all preparations are concluded and you can start the impedance and reflex measurement. Please read the following chapters.

min 0 mm max 1 mm

Figure 9 Proper placement of eartip

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Operating Instructions MI 34, MI 34h 4 How to create a Tympanogram In the following paragraph we will briefly explain the principle and the background of the impedance measurement to create a better understanding. If you want to begin the measurements immediately, just skip this paragraph and continue reading section 4.3 “Preparing the Measurements.”

4.1 The basics of the impedance measurement The impedance measurement assists in diagnosing of the condition of the middle ear and can therefore not be compared directly with other audiometric tests such as sound or speech audiometry which assists in the measurement of hearing. Furthermore the impedance measurement is an objective measuring method which does not depend on the cooperation of the test person and can therefore not be falsified by the patient. The two most important impedance measuring methods possible with your MI 34 are tympanometry and the measurement of the Stapedius reflex which is discussed in chapter 5: “How to measure the Stapedius reflex.”

musculus stapedius

hearing nerve

middle ear bones ear canal ear drum

cochlea

middle ear eustachian tube

Figure 10 The middle ear

Figure 11 Principle of the impedance measurement

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Operating Instructions MI 34, MI 34h The impedance measurement examines the acoustic resistance of the middle ear. If the eardrum is hit by a sound, part of the sound is absorbed and sent via middle ear to the inner ear while the other part of the sound is reflected. The stiffer the eardrum is the more sound is reflected and the less sound reaches the inner ear. Inside the probe of the impedance measuring instrument a small loudspeaker is installed which emits a low frequency sound through a tube (figure 11: A) into the auditory canal before the eardrum. Another tube (figure 11: B) is connected to the microphone inside the probe which receives the sound. Together with a third tube (figure 11: C), all three are inserted nearly to the eardrum and are made airtight against outside pressure by the eartip. A manometer and a pump, which can produce both positive and negative pressure, are connected with tube C. Less sound is reflected to the microphone when the eardrum is stiff and the eardrum transmits the majority of the sound via the middle ear to the inner ear. The highest compliance is normally reached with an air pressure corresponding to the outside pressure.

So you can draw conclusions on the condition of the middle ear from the form and the values of the tympanogram.

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2.0 2,0 1.6 1,6

Compliance ( ml)

When performing tympanometry during a measurement, a continuous change of positive and negative pressure is produced by the pump of the instrument in the outer auditory canal. The compliance is measured simultaneously and shown in a diagram (the tympanogram) which illustrates the compliance in ml over the pressure in daPa. In figure 12, the area for normal tympanogram curves is hatched. Here you can see that the highest compliance is reached with normal pressure. When you create positive and negative pressure the eardrum stiffens the compliance decreases.

1.2 1,2 0.8 0,8 0.4 0,4

00

-300 -200 -100 0 +100 Pressure ( daPa )

Figure 12 Tympanogram (normal curve area is hatched)

Operating Instructions MI 34, MI 34h 4.2 Preparing the patient Explain to the patient that the measurement is painless and that nothing enters the auditory canal. The patient does not have to respond when there are loud test sounds or when the pressure in the auditory canal changes. In no case should the patient swallow, chew or move during the measurement.

4.3 Preparing the measurement The LCD shows the empty measurement screen for the right ear and the control light of the probe turns red. To measure the left ear, change the side by pressing the L/R key or the probe button M . Then the selected test ear shown in the middle-top of the LCD will change from RIGHT to LEFT and the control light of the probe will turn blue. Switch off the reflex measurement by pressing the Reflex key 3 . The word Tympanometer must appear at the right top of the display. Make sure the auditory canal is clear. Choose an eartip according to the size of the auditory canal and put it firmly onto the probe tip (see figure 9 in chapter 3.7).

4.4 Measuring the tympanogram Take hold of the top of the outer ear and pull it back. Insert the probe with the eartip into the auditory canal until the Impedance Right Tympanometer control light of the probe is green indicating the start of the Status ml 3 READY test. Do not move the probe until Ear Volume the green light goes out; the 2 patient must not swallow or Compliance speak during the measurement. 1 During the test the LCD will Pressure display the tympanogram on the 0 left side while the test is running Gradient -600 -300 300 daPa and the values will appear on the right side. After about 4-5 Scale seconds the test is completed Figure 13 and the green light turns off. Measurement screen (only tympanogram) Now you can remove the probe from the ear. If an error occurs during the measurement the test will stop. If leakage occurs, the control light of the probe turns yellow and Leaking will appear under Status. If the probe is blocked, the control light of the probe turns yellow and Blocked will appear under Status. Please proceed as described in chapter 3.6 “Getting familiar with the probe.” To measure the other ear, change the side by pressing the L/R key or the probe button and repeat the measuring procedure described above.

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Operating Instructions MI 34, MI 34h 4.5 How to evaluate the tympanogram display After having completed a measurement you can see the results on the LCD. On the left side of the display you see a graph of the tympanogram. The area surrounded by the box is valid for “normal” tympanograms. You can change the area or turn it off.

Impedance

3

Right

Tympanometer Status READY

ml

2

Ear Volume 0.94 ml

1

Compliance 0.81 ml

0

Pressure - 37 daPa

-600

-300

For details see chapter 11 “Individual Setup of the MI 34.”

300 daPa

Gradient 32 daPa

Scale

Figure 14 Display of a normal tympanogram

In the top-middle of the LCD, the words Right or Left indicate the ear chosen at the moment. Tympanometer (at the top right) - indicates that the reflex measurement has been switched off. In the boxes to the right the following test measurements are displayed: Ear Volume - indicates the volume of the section of the auditory canal between the eartip and the eardrum in ml (in the example 0.94 ml). Compliance - indicates the maximum value of the compliance from the tympanogram in ml (in the example 0.81 ml). Pressure - indicates the pressure with the highest measured compliance (in the example -37 daPa). Gradient - calculations are reported as the tympanogram width at half of peak compliance expressed in daPa (in the example 32 daPa).

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Operating Instructions MI 34, MI 34h 4.6 How to print the test result After the end of a test you can print the results for your records by pressing the Print button 1 . The quiet thermal printer prints out the example used in the previous paragraph in only six seconds. While the printer is working, no key action is possible and the probe is inactive. Figure 15 shows the printout. Id No: Patient’s Id number. Date: Actual test date. Name: Name of the patient. Examiner: Name of the examiner.

MAICO MI 24 Id No.:

Date:

Name: Examiner: Remarks:

Remarks: Additional information about the test or patient. All other values and the tympanogram correspond to those you have seen on the LCD (explained on the previous page under 4.5). The “intelligent” printer control helps you save paper. It will only print out what was actually measured. The printout in the example above does not show reflex frequencies because only the tympanogram was measured. If you have saved two tympanograms (for example, both the left and the right ear) they are printed side by side.

Tympanogram Right 3

ml

2

0.94 ml

1

0.81 ml

0

- 37 daPa

-600

-300

Ear Volume Compliance Pressure Gradient

300 daPa

32 daPa

0.94 ml 0.81 ml -37 daPa 31 daPa

Figure 15 Printout of a normal tympanogram

You can produce as many printouts as you want by pressing the Print button several times.

4.7 How to delete the test results By holding down the R/L key for at least two seconds and the measurement memory will be deleted. On the LCD the message Delete all Data? appears. Press Enter to delete all patient data. Then the LCD shows an empty measurement screen. If you press the Menu button, you return to the measurement screen without deleting the measurement data.

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Operating Instructions MI 34, MI 34h 5 How to create a tympanogram with high probe tone In addition to the standard 226 Hz probe tone tympanometry, the MI 34h has a higher frequency probe tone that can be selected by the user. A tympanogram recorded using the high probe tone is generally better suited for screening newborns and provides more accurate results for those subjects.

5.1 To select high probe tone frequency When the instrument is switched on, it automatically powers-up in the standard tympanometry mode. In order to choose tympanometry with high probe tone, hold down the Reflex key for two seconds. The screen for high probe tone tympanometry looks very similar to the normal tympanometry mode, however the following differences will appear on the screen: • The scaling is now measured in mmho • The pre-selected frequency (1000 Hz) is displayed in the upper left hand side of the screen The tympanometry test with high probe tones is performed in the exact same way as a normal tympanometry test. It is possible to perform normal tympanometry and high probe tone tympanometry in one test session and print the results for comparison. When the first tympanometry curve has been drawn, press the Reflex key for two seconds to switch to high probe tone tympanometry. Now the next curve will be drawn automatically. Press Print and a printout presenting both curves will appear. Note: It is not possible to perform reflexes on the basis of a high probe tone tympanogram.

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Operating Instructions MI 34, MI 34h 6 How to measure the Stapedius reflex 6.1 The basics of the Stapedius reflex measurement While tympanometry measures the musculus hearing stapedius change of the compliance caused by nerve changing pressure in the outer middle auditory canal, the Stapedius reflex ear measurement works with a bones changing compliance caused by contraction of the Stapedius muscle ear canal in the middle ear. The contraction cochlea ear drum called Stapedius reflex - causes a middle ear decrease in compliance and is caused by loud acoustic stimuli. eustachian tube Regardless whether the acoustic Figure 16 stimulus is active on the left or on The middle ear the right or on both sides the Stapedius reflex is always binaural, i.e. it occurs in both ears at the same time. The Stapedius reflex is caused in ears of adults with normal hearing with sound pressure levels between 70 and 105 dB. In the probe ear, the reflex method continuously measures the compliance with the pressure which was caused before the highest compliance measurement. Simultaneously the stimulus ear is irritated by the sound which causes the contraction of the Stapedius muscle. The ipsilateral reflex measurement uses the same ear for the probe and the stimulus.

Figure 17 Ipsilateral test

The contra-lateral measurement uses different ears for the probe and the stimulus. The acoustic stimulus is applied to the ear opposite the probe ear. If the applied stimulus causes a reflex, the impedance measuring instrument registers a decrease in compliance in the “probe ear” which indicates a Stapedius reflex at the actual test frequency and the test level. The test level which was set when the reflex occurred is called reflex threshold and is shown in dBHL (dB hearing level).

Figure 18 Contralateral test

6.2 Preparing the patient In addition to the general introduction described in chapter 4.2, explain to the patient that loud test sounds will occur during the reflex measurement. It is very important that the patient does not move because a reflex can be registered with a change of compliance of 0.05 ml.

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