Tympanometry

 Statement topic

 Action recommendation

Evidence Quality

Strength of Recommendation

Study type

reference

1.Equipment

1.1. The tympanometer and probe tip shall be clean (i.e. free from dust and dirt and in compliance with local infection control standards).   Tympanometers shall meet the performance and calibration requirements of BS EN 60645–5.

Very low

Strong

Expert opinion

2,3,4

1.2. Calibration: The calibration of the instrument shall be checked  daily with the probe fitted to an appropriate cavity such as the one supplied by the manufacturer. The performance of the instrument shall also be checked on an ear known to produce a normal, peaked tympanogram (e.g. to ensure the pump is operational and its tube is not blocked).

Very low

Strong

Expert opinion

2,3,4

2.Subject prepa- ration

 2.1. Before examination, the subject (or the person responsible for the subject) should be asked if he/she currently has any ear-related symptoms (including discomfort, pain and discharge), is currently being treated for any ear-related problems or has previously had surgery involving the ears.

Very low

Conditional

Expert opinion

2,3

2.2. The subject should be seated comfortably and should  remain as still as possible during the test.

Very low

Strong

Expert opinion

2, 5,6

2.5. Young children may need to be held by an appropriate      adult, which should be the person responsible for the child.

low

Conditional

Observational study

7

3.Otoscopic ex- amination

3.1. Tympanometry should be preceded by   otoscopic examination to ensure that there are no contraindications to continue. Otoscopy in neonates is only intended as a general inspection of the outer ear for obvious signs of disease, blockage or malformation.

low

Strong

Observational  validation study

2,8

4.Informed con- sent

4.1. Testing should proceed only with informed consent (e.g. verbally) from the subject or person responsible for the subject and if it is the judgement of the tester that it is safe to do so.

Very low

Conditional

Expert opinion

2,5

5.Subject instruc- tions

5.1. The examiner should explain, and where necessary demonstrate, the procedure to the subject and/or person responsible for the subject.

Very low

Conditional

Expert opinion

2,5

6.Test procedures

6.1  Subjects with age over 6 months, using a 226-Hz probe tone is recommended:

• Fit a clean tip of suitable size and shape to the probe and straighten the ear canal by gently pulling the pinna.

• Point the probe in the direction of the tympanic membrane to avoid the risk of occluding the probe aperture, for example against the wall of the canal.

• A slow rate of change of pressure (50 daPa s–1 or less) should be used but with young children it may be beneficial to use a faster sweep, sacrificing some accuracy for speed of operation.

• In the absence of other requirements, tracking should commence at +200 daPa and end once the peak, if it exists, has been clearly recorded.

• On automatic systems a lower limit of about –300 daPa, depending on instrument, should normally be selected but occasionally it may be necessary to go to

–600 daPa in search of a peak.

• In cases of normal tympanograms, tracking should stop at –200 daPa for adults and –300 daPa for children to minimise discomfort.

• When testing adults and children on the same equipment, all test parameters should be checked and set appropriately prior to testing.

• If an unexpected result is obtained the test should be repeated in its entirety, that is, by removing the probe, inspecting the ear, checking the probe to ensure it is not blocked, for example with wax, and re-testing.

• Unexpected results should not be accepted without verifying that they are repeatable and running a calibration check of the probe in the test cavity and performing biologic calibration.

• After tympanometry has been completed the probe tip should be removed and all contaminated tips shall be disposed of or cleaned as per local policy.

Very low

Strong

Expert opinion

2, 9

 6.2  Subjects with a corrected age under 6 months using a 1000-Hz probe tone

• Fit a clean tip of suitable size and shape to the probe and straighten the ear canal (e.g. by gently pulling the pinna downwards and outwards).

• Point the probe in the direction of the tympanic membrane to avoid the risk of sealing the tip against the wall of the canal.

• Movement of the infant and crying can result in a false peak in the tympanogram. The baby does not need to be asleep but should definitely be resting quietly during the test.

• The direction of pressure change should be from positive to negative and the range should be at least from +200 daPa to –400 daPa (and preferably– 600daPa).

• A fast screening mode speed of up to 600daPa s–1 should be used.

• Traces should usually be repeated, if possible, to check that the result is repeatable and not due to artefacts such as baby movement. It is especially important to retest any ear with an abnormal or difficult-to-interpret tympanogram.

• After tympanometry has been completed the probe tip shall be removed and all contaminated tips shall be disposed of or cleaned as per local policy.

low

Strong

Observational study

2,9,10

7.Results and reporting

7.1.Tympanometric results do not identify pathology uniquely and should be interpreted in the context of other information from the complete test battery being conducted and with particular regard to the otoscopic findings and history.

    low

Strong

Observational study

2, 11