HealthMedicine

Impedanceometry - what is it and how is it conducted?

Throughout life our senses can lead us down: a decrease in hearing, sight, smell. Sometimes it happens very early, sometimes - it's late, but somehow we get to see a doctor. One such specialist is an otorhinolaryngologist. It is he who will understand the causes of the ailment.

Impedanceometry: what is it?

Impedanceometry is an instrumental diagnostic method that helps determine the location and nature of hearing impairment. With its help, you can get information about the condition of the auditory tube, the cochlea, the middle ear, and also innervating their nerves.

This method allows you to identify diseases such as perforation of the tympanic membrane, tympanosclerosis, impaired patency of the auditory tubes, otitis media, otosclerosis and others.

Acoustic impedance measurement is an automatic measurement of the acoustic conductivity shift in the middle ear as the pressure of the air column changes and the effect of sound. The main test value is acoustic admittance, or the conductivity of the outer and middle ear structures and their resistance to sound.

Timponometry

Acoustic impedance measurement involves measuring the conductivity of sound after changing the air pressure. This is called tympanometry. The equipment records the change in admittance when the pressure is raised to two hundred millimeters of water column and falls below -400 millimeters.

Admittans depends on how great the difference between the pressure in the external ear canal and the middle ear. The highest value of this indicator is recorded when the pressure is the same. On the tympatogram this moment is shown as the highest peak. The increase or decrease in pressure gives characteristic changes in the curve. Normally, it should look like the letter "L". The violation of the function of the middle ear changes the amplitude and shape of the tympanogram.

Examination of ventilation function of the auditory tube

Impedanceometry - what is it? This is a method of comprehensive examination of the hearing system for its reduction or distortion. One of the reasons may be a violation of the functions of the auditory tube. Its overlap causes the proliferation of adenoid vegetations, splitting of the plate of the hard palate, oncological diseases of the nose and mouth, and swelling of the mucous membrane. Children sometimes have impaired patency of the auditory tubes due to a decrease in the elasticity of the tissues or impaired muscle function of the palatal curtain.

Impedansometry of the ear for determining the patency of the auditory tube is divided into three stages:

  1. Control check. It is produced at normal pressure on both sides of the tympanic membrane.
  2. The Valsalva experience. In the nasopharynx, an increased pressure is created artificially, and the patient is asked to close his mouth and nose. At normal patency of a pipe the highest value on a tympatogram (peak) will coincide with the moment of the greatest pressure.
  3. Toynbee's experience. Fixing the ventilation capabilities of Eustachian tubes at low pressure. For this, the patient is asked to take a sip by closing the mouth and nose.

Reflexometry

In order to check whether there is a contraction of the stremna muscle (it stretches the tympanic membrane) after exposure to sounds, acoustic impedance measurement is used. How is this procedure carried out? The ear is affected by noise of varying intensity and loudness to check for the presence of an acoustic reflex.

In healthy people, the threshold of this reflex is in the range of sixty to ninety decibels. Change the tension of the tympanic membrane recorded on both sides, even if the sound came only in one ear. This reflex refers to the unconditioned.

There are two ways to perform this procedure:

  1. Ipsilateral, when sound is isolated in the ear that needs to be examined.
  2. Contralateral, if the noise is directed into the ear, which is not being investigated at the moment.

For the reflexometry, sounds are used with a frequency of five hundred, one thousand, two thousand and four thousand hertz, as well as broadband noise.

Diagnostic value of the procedure

Why is impedance measurement necessary? What is it and why do it? This relatively simple procedure makes it possible to identify the patient's conductive and sensorineural hearing loss, the defeat of the seventh or eighth pair of cranial nerves, the trunk of the brain. The study is non-invasive, painless and accessible to any patient, regardless of his age and well-being.

Diagnostic criteria for sensorineural hearing loss are the following situations:

- acoustic reflex is observed at a noise level less than fifty decibels;
- from fifty to eighty decibels, the reflex is registered proportionally to the amplification of sound;
- after eighty decibels the reflex is absent.

Acoustic reflexometry does not yield results with conductive hearing loss, which makes it possible to use this feature to differentiate it from the sensorineural one. The defeat of the facial nerve gives a reflex on the contralateral side, but its absence is on the affected one. And if the auditory nerve reflex is broken, neither from the side of the affected ear, nor from the healthy side.

Impedance of the esophagus

Esophageal impedance measurement: what is it? This is a method of determining the muscular contractions of the esophagus walls, as well as the passage of liquid and gases along it. It is based on measuring the resistance between two electrodes, which are injected into different parts of the digestive tube. Simultaneously with this study, acidity is measured.

The procedure allows to determine the type of reflux disease (acid, neutral or alkaline) and its structure (gas or liquid). Diagnostic criteria for GERD (gastroesophageal reflux disease) is a decrease in the pH of the medium to four or less, but modern studies disprove this theory. Therefore, the daily impedance of the esophagus was of great importance.

To do this, a thin probe is inserted through the nose to the patient, at which sensors are located at the same interval. This device allows you to register the peristalsis of the esophagus and the acidity of the contents, which gets into it from the stomach.

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