Hearing Tests: From 1 Different Sources
Tests carried out to assess hearing. Hearing tests are performed as part of a routine assessment of child development and when hearing impairment is suspected. The tests are sometimes included in a general medical examination. Hearing tests may also be used to identify the cause of tinnitus or dizziness.
An audiometer (an electrical instrument) is used to test an individual’s ability to hear sounds at different frequencies and volumes. The lowest level at which a person can hear and repeat words (the speech reception threshold) is tested, as is the ability to hear words clearly (speech discrimination). The type of hearing loss (see deafness) is determined by holding a tuning fork to different parts of the ear.
See DEAFNESS; EAR.... hearing
Most vision tests examine a person’s sharpness of VISION (visual acuity) and often of the ?eld of vision (see VISION, FIELD OF). Refraction tests assess whether a person has an error that can be corrected with glasses such as ASTIGMATISM, HYPERMETROPIA or MYOPIA. Visual acuity is tested using a Snellen chart when the patient tries to read letters of di?ering standard sizes from 6 metres away. The optician will prescribe lenses to correct any defects detected by vision tests.... vision tests
Tests to screen for and diagnose bleeding disorders, usually resulting from deficiencies or abnormalities of blood coagulation factors or of platelets (see blood clotting). Tests are also used to monitor treatment with anticoagulant drugs.... blood-clotting tests
Analysis of a sample of blood to give information on its cells and proteins and any of the chemicals, antigens, antibodies, and gases that it carries. Such tests can be used to check on the health of major organs, as well as on respiratory function, hormonal balance, the immune system, and metabolism. Blood tests may look at numbers, shape, size, and appearance of blood cells and assess the function of clotting factors. The most important tests are blood count and blood group tests if transfusion is needed. Biochemical tests measure chemicals in the blood (see acid–base balance; kidney function tests; liver function tests). Microbiological tests (see immunoassay) look for microorganisms that are in the blood, as
in septicaemia. Microbiology also looks for antibodies in the blood, which may confirm immunity to an infection. blood transfusion The infusion of large volumes of blood or blood products directly into the bloodstream to remedy severe blood loss or to correct chronic anaemia. In an exchange transfusion, nearly all of the recipient’s blood is replaced by donor blood. Before a transfusion, a sample of the recipient’s blood is taken to identify the blood groups, and it is matched with suitable donor blood. The donor blood is transfused into an arm vein through a plastic cannula. Usually, each unit (about 500 ml) of blood is given over 1–4 hours; in an emergency, 500 ml may be given in a couple of minutes. The blood pressure, temperature, and pulse are monitored during the procedure.
If mismatched blood is accidentally introduced into the circulation, antibodies in the recipient’s blood may cause donor cells to burst, leading to shock or kidney failure. Less severe reactions can produce fever, chills, or a rash. Reactions can also occur as a result of an allergy to transfused blood components. All
blood used for transfusion is carefully screened for a number of infectious agents, including HIV (the AIDS virus) and hepatitis B and hepatitis C.
In elderly or severely anaemic patients, transfusion can overload the circulation, leading to heart failure.
In patients with chronic anaemia who need regular transfusion over many years, excess iron may accumulate (haemosiderosis) and damage organs such as the heart, liver, and pancreas.
Treatment with desferrioxamine to remove excess iron may be needed.... blood tests
See pulmonary function tests.... lung function tests
Questionnaires designed to define various personality traits or types. Tests may be designed to detect psychiatric symptoms, underlying personality traits, how outgoing or reserved a person is, and predisposition to developing neurotic illness.... personality tests
See pulmonary function tests.... respiratory function tests
A group of blood tests used to evaluate the function of the thyroid gland and to detect or confirm any thyroid disorder. The thyroid hormones T3 and T4 are measured, as well as thyroid-stimulating hormone (TSH), the pituitary gland hormone that stimulates the thyroid gland.... thyroid-function tests
Skin tests used to determine whether or not a person has been exposed to the bacterium that causes tuberculosis. Tuberculin tests are carried out for diagnosis of tuberculosis, and before BCG vaccination. A small amount of tuberculin (purified protein from the bacteria) is injected into the skin. A few days later, the skin reaction, if any, is noted. A reaction indicates previous exposure.... tuberculin tests
Hearing tests carried out to diagnose conductive deafness. In the Weber test, a vibrating tuning fork is held against the forehead. If there is conductive hearing loss, the sound seems louder in the affected ear. In the Rinne test, a vibrating tuning fork is held first near the ear, and then against the bone behind it. If it sounds louder when held against the bone, there is conductive hearing loss.... tuning fork tests
See urinalysis.... urine tests
see contralateral-routing-of-signal hearing aid.... bicros hearing aid
where clinical *negligence is claimed, tests used to determine the standard of care owed by professionals to those whom they serve, e.g. the standards of care provided to patients by doctors. The 1957 case of Bolam v Friern Hospital Management Committee established that if a doctor acts in accordance with a responsible body of medical opinion, he or she will not be negligent. In 1997 this standard of care test was amended by the case of Bolitho v City and Hackney Health Authority, which requires the doctor’s behaviour to satisfy the judgment not only of responsible medical opinion but also of a court’s own independent logical analysis.... bolam and bolitho tests
(BAHA) a specialized form of *hearing aid for patients with certain forms of conductive *deafness. A small titanium screw is surgically fixed into the bone of the skull behind the external ear using a process called *osseointegration. Sound energy is passed from a miniature microphone and amplifier to the screw, through the bone, to the *cochlea.... bone-anchored hearing aid
(CROS hearing aid) a form of hearing aid used to help people with severe or profound unilateral hearing loss. Sound information is collected by a microphone worn on the affected side and then transmitted by a thin wire or Bluetooth wireless technology to a device worn on the opposite side. If the hearing in the better ear is normal, no amplification is applied to the signal. If the better ear has a hearing loss the device also acts as a conventional hearing aid and amplifies the signal from both sides: this is known as a BICROS hearing aid.... contralateral-routing-of-signal hearing aid
see contralateral-routing-of-signal hearing aid.... cros hearing aid
see hearing aid.... digital hearing aid
any of various devices for helping people with hearing difficulties. Environmental aids include *assistive listening devices and alerting devices, such as door bells with visible as well as audible alarms, infrared links to televisions, and vibrating alarm clocks.... environmental hearing aid
the support and rehabilitation of people with hearing difficulties, tinnitus, or vertigo. It includes supplying help with acclimatizing to *hearing aids, teaching lip-reading, advising on *environmental hearing aids, and offering general information and advice regarding the auditory system. Other functions are to explain such conditions as *Ménière’s disease and *otosclerosis and to provide *tinnitus retraining therapy (TRT) and other forms of tinnitus management.... hearing therapy
a form of hearing aid in which a small electrical vibrator is surgically attached to the auditory *ossicles. An external device with a microphone and an electronic processing unit passes information to the implanted device using radio-frequency waves. The external part is located behind the pinna and is powered by batteries.... implantable hearing aid
tests for assessing the function of the kidneys. These include measurements of the specific gravity of urine, creatinine *clearance time, and blood urea levels; intravenous urography; and renal angiography.... renal function tests
(DSTs) tests based on the principle that appropriate doses of *dexamethasone can suppress the output of cortisol from the adrenal glands in the normal state and that this ability is reduced or lost in *Cushing’s syndrome. In the overnight DST 1 mg of dexamethasone is administered at midnight and the serum cortisol level is measured at 9.00 am the next morning. Failure to suppress cortisol output may indicate Cushing’s syndrome but also occurs in patients with obesity and depressive illness. In the low-dose DST (0.5 mg dexamethasone every 6 hours for 48 hours), cortisol suppression occurs in patients with obesity and depression but not in those with Cushing’s syndrome. In the high-dose DST (2 mg dexamethasone every 6 hours for 48 hours), cortisol is suppressed in patients with Cushing’s disease (in which excess amounts of ACTH are secreted by the pituitary gland) but not in those with Cushing’s syndrome due to other causes. Although the low- and high-dose tests are unreliable, all three tests should be performed to aid the diagnosis of Cushing’s syndrome.... dexamethasone suppression tests
a device to improve the hearing. Simple passive devices, such as ear trumpets, are now rarely used. An analogue hearing aid consists of a miniature microphone, an amplifier, and a tiny loudspeaker. The aid is powered by a battery and the whole unit is small enough to fit behind or within the ear inconspicuously. If necessary, aids can be built into the frames of spectacles. In a few cases of conductive hearing loss the loudspeaker is replaced by a vibrator that presses on the bone behind the ear and transmits the sound energy through the bones of the skull to the inner ear. Digital hearing aids are in some respects similar to analogue aids but in addition to the microphone, amplifier, and loudspeaker, they have digital-to-analogue converters and a tiny computer built into the casing of the aid. This enables the aid to be programmed to the patient’s particular requirements and generally offers improved sound quality. See also bone-anchored hearing aid; cochlear implant; environmental hearing aid; implantable hearing aid.... hearing aid
Standard Tests for Young Children and Retardates: tests to detect visual problems in children between the ages of six months and five years. They consist of a series of standardized balls, toys, or letters. The tests were developed by the paediatrician Mary Sheridan.... stycar tests
tests used to assess the ability of the adrenal cortex to produce cortisol. Serum cortisol is measured before and then 30 minutes (or 5 hours) after an intramuscular injection of 250 ?g (or 1 mg) tetracosactide (Synacthen), an analogue of *ACTH. The adrenal glands are considered to be inadequate if there is a low baseline concentration of cortisol or the rise is less than a certain predefined amount.... synacthen tests
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