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Biomedical subjects

O Tjernström

Publications and source records attributed to O Tjernström.

At least 19 recordsLinked to original sources
PubMed1999

Electrocochleographic and audiometric evaluation of hypobaric effect in Meniere's disease.

OBJECTIVES: To elucidate the effects of hypobaric pressure on cochlear hydrodynamics in patents with well-defined Meniere's disease. DESIGN: Sixteen patients were consecutively selected. Elevated hearing threshold levels and pathological transtympanal electrocochleography (tt-ECOG) were confirmed at the day of trial. The patients were exposed to repeated episodes of hypobaric pressure in a pressure chamber. The rate (20 daPa/s) and magnitude (-285 daPa) of chamber pressure change were low. The induced tympanic overpressure (+185 daPa) was continuously monitored and any tympanic equilibration was avoided. METHODS: The results of Bekesy and speech audiometry as well as tt-ECOG performed immediately before and after exposure were compared. The importance of chamber pressure change, number of hypobaric episodes, duration of exposure, and the induced relative tympanic overpressure was tested. RESULTS: It is shown that the relative tympanic overpressure is the most important factor to affect the cochlear hydrodynamics. Higher relative overpressure was associated with improvement of hearing threshold levels, while the ECOG results tended to improve with lower induced tympanic overpressure. CONCLUSION: The importance of tympanic overpressure shown in this study is in agreement with previous findings from hypobaric animal experiments. The inverse relation of psychoacoustic and ECOG tests suggests that the two methods evaluate different parameters, perhaps contributing differently to the physiology of hearing.

Adult↗
PubMed1998

[Barotrauma in children and adults after flying. Prevalence and treatment with Otovent].

To prevent barotitis during descent in aviation, the ears have to be cleared several times by performing the Valsalva's manoeuvre. The manoeuvre is difficult for children to perform, and they are therefore at high risk of developing barotitis. The treatment of barotitis is either inflation by a Politzer balloon or myringotomy. An alternative treatment is autoinflation using the Otovent. This prophylaxis/treatment can be performed by the child with assistance from its parents as soon as or preferably before the descent has started. The prevalence of barotitis amongst 45 children and 49 adults in transit was found to be highest in children, 28%, compared with adults, 10%. Only 6% of the children with negative middle ear pressure after flight managed a successful Valsalva manoeuvre, whereas 33% could normalise the middle ear pressure by inflating the Otovent. In conclusion we recommend autoinflation using the Otovent set by children and adults who have problems clearing their ears during flight.

Acoustic Impedance Tests↗
PubMed1998

Point prevalence of barotitis in children and adults after flight, and effect of autoinflation.

The most common cause of barotitis is pressure changes during descent in aviation. Equilibration is normally achieved by swallowing, jaw movements, yawning, or chewing, but some have to perform a Valsalva maneuver several times during descent and even by these means some fail. The aim of the study was to estimate the point prevalence of barotrauma in children and adults after flight, and to test the effect of an autoinflation device (Otovent), in improving negative middle ear pressure after flight. Questionnaires and Otovent, were distributed to all air passengers in eight incoming flights. The questionnaires inquired about nasal allergy, nasal congestion, previous and actual ear pain, use of decongestants and experience of inflating the Otovent set during descent. After flight, the passengers were offered an ear examination including otoscopy and tympanometry both before and after a Valsalva maneuver, as well as after Otovent inflation. Otoscopic signs of barotitis were found in 10% of the adults and in 22% of the children. Negative middle ear pressure of more than 10 hPa after landing was found in 20% of the adults and in 40% of the children. The Valsalva maneuver normalized the pressure in 46% of the adults and in 33% of the children. Of the adults, 73%, and of the children, 69% with an unsuccessful Valsalva maneuver could improve or normalize the middle ear pressure by inflating the Otovent set. In conclusion, we recommend autoinflation using the Otovent set to air passengers with problems clearing the ears during flight.

Acoustic Impedance Tests↗
PubMed1998

Drug-induced changes in eustachian tube function.

Many studies have shown that antihistamines and decongestants are of little use in the treatment of acute otitis media and otitis media with effusion, or in the prophylaxis of these disorders. However, because some drugs can improve otitis media with effusion (glycocorticosteroids) and some can impair the opening function of the eustachian tube (atropine), it seems justified to continue studies of eustachian tube function and medication.

Adrenal Cortex Hormones↗
PubMed1996

Barotitis in children after aviation; prevalence and treatment with Otovent.

Barotitis is an acute or chronic inflammation caused by environmental pressure changes. The most common cause is the pressure change during descent in civil aviation. To prevent barotitis the middle ear pressure has to be equalised several times during descent. This can be achieved by performing the Valsalva manoeuvre, but for children, many of whom have a dysfunction of the Eustachian tube, this is difficult to perform and they are therefore at high risk of developing barotitis during flight. The traditional treatment modalities of barotitis are inflation by a Politzer balloon, myringotomy or prophylactic grommet insertion. An alternative treatment or prophylactic measure is autoinflation using the Otovent treatment set. This prophylaxis/treatment can be performed by the child with assistance from its parents as soon as possible or rather before the descent has started. The prevalence of barotitis amongst transit passengers was found to be highest in young children, 25 per cent, compared with adults, five per cent. Only 21 per cent of the youngest children with negative middle ear pressure after flight managed a successful Valsalva's manoeuvre, whereas 82 per cent could increase the middle ear pressure inflating the Otovent set. In conclusion we recommend autoinflation using the Otovent set by children and adults with problems clearing the ears during flight.

Acoustic Impedance Tests↗
PubMed1990

Does administration of an aminoglycoside in a single daily dose affect its efficacy and toxicity?

Treatment efficacy, oto- and nephrotoxicity, and aminoglycoside pharmacokinetics were evaluated in a prospective, comparative, randomized clinical study of aminoglycosides given once a day or three times a day for severe infections. Sixty patients were treated with netilmicin or gentamicin 4.5 mg/kg bodyweight/day, either once a day or divided into three doses a day. The patients were allocated randomly to the different groups. The clinical effect was difficult to compare in the different groups, because of the small numbers of patients. Therapeutic failures were seen in seven patients (three after one and four after three doses per day). Two patients, one with Staphylococcus aureus endocarditis and one with streptococcal endocarditis, on netilmicin once daily and conventional high-dose therapy with a penicillin had positive blood cultures after five and seven days of treatment, respectively. Vestibular function and hearing acuity were examined by serial audiograms and electronystagmograms. In spite of extensive diagnostic evaluation, only two cases of ototoxicity were detected. One patient treated with gentamicin three times a day developed vertigo and a severe abnormality of her electronystagmogram. One young patient treated with gentamicin once daily had a slight bilateral reduction of hearing. Nephrotoxicity was mild and did not differ in the four treatment groups. This was the first investigation of a once-daily dosing regimen conducted in seriously ill patients with systemic infections. We could not demonstrate any evidence that aminoglycoside treatment once daily has greater oto- or nephrotoxicity than the traditional three times daily regimen.

Audiometry↗
PubMed1989

Effect of terbutaline on human eustachian tube function.

Terbutaline, a beta 2-adrenoceptor agonist, was administered subcutaneously to 10 healthy adult subjects. The pressure opening level (Pol) of the Eustachian tube (ET) and the remaining middle ear pressure when the ET closed (Pcl) after passive equilibration were measured as well as parameters for active tubal function. A quantitative impedance method in combination with a pressure chamber was used. Pol was reduced by 0.29 +/- 0.10 (-7.3%) kPa 90 min after injection of terbutaline 5 micrograms/kg body weight. There was also a decrease in Pcl, 0.17 +/- 0.06 kPa (-14.0%). No such decrease was seen after saline solution injected subcutaneously. It is suggested that terbutaline facilitates the ET opening by stimulating the secretion of surface tension lowering substances.

Eustachian Tube↗
PubMed1988

Tubal function and surgery in chronic otitis media. A study on the predictive value of testing tubal function, Valsalva's manoeuvre and volume of ear spaces.

In 141 ears with central tympanic membrane (TM) perforation preoperative tubal studies as well as volume determination of the air-filled ear spaces was performed. Tubal patency was checked with Valsalva's manoeuvre and pressure equilibration function with Toynbee's test and aspiration-deflation tests respectively. At postoperative control 74.5% of the ears had intact movable TM (healed), 5.7% had intact but immovable or retracted TM and 19.8% had perforation (defect). There was no difference between the healed and defect ears regarding results in aspiration-deflation tests. A positive Valsalva's manoeuvre was significantly more frequent in the healed ears. Ears with a small air-filled volume and negative Valsalva's manoeuvre showed significantly lower healing rate than ears with positive Valsalva's manoeuvre and a large air-filled volume.

Adult↗
PubMed1987

Effect of body position, epinephrine, and a surface-tension-lowering substance on the eustachian tube opening in the rat.

The middle ear pressure was increased by air injections and the level (pressure opening level = Pol) at which the Eustachian tube (ET) opened was determined in anaesthetized ras. At a rate of pressure increase of 0.7 kPa/s it opened at 4.1 +/- 0.4 kPa. A change of the body and head position from horizontal to almost vertical increased the Pol by about 0.4 kPa (head downwards) and decreased the Pol by about 0.3 kPa (head upwards). Epinephrine tested in a dose-response experiment had no significant effect on Pol (doses from 0.01 to 10 micrograms/kg body weight). A surface-tension-lowering substance, Tween 20, instilled into the middle ear, reduced Pol by about 1 kPa. A change in body and head position had thus a moderate effect on the passive opening of the ET, a strong decongestant had no effect, and a surface-lowering substance, a marked effect. With increasing rates of pressure change in the middle ear, Pol increased. After instillation of Tween 20 there was an almost parallel shift to lower values of the regression line of the Pol at different rates of pressure increase.

Animals↗
PubMed1985

Effect of atropine on the eustachian tube function.

The effect of atropine on the eustachian tube function was studied by means of a recently designed method. The results out of 20 examined ears showed that atropine significantly reduced both active and passive functions of the eustachian tube. The findings are discussed and it is concluded that the method used might be a valuable tool in forthcoming studies of pharmacological effects on the eustachian tube function.

Air Pressure↗
PubMed1984

Eustachian tube function measured as pressure equilibration and sound transmission capacity. A comparison in healthy ears.

In a series of 68 healthy ears the muscular opening function of the Eustachian tube was assessed in two different ways. A pressure equilibration capacity of +/- 100 mm H2O was tested by a quantitative impedance technique using a pressure chamber and compared to sound transmission capacity recorded by sonotubometry at frequencies of 6, 7 and 8 kHz. In contrast to the pressure equilibration test, sonotubometry does not allow a quantitative assessment of Eustachian tube function and furthermore, sonotubometry yields false-positive as well as false-negative results due to the great variations in sound pressure generated by the deglutition maneuvers themselves.

Adult↗
PubMed1984

Pressure chamber tests for selection of aircrew.

The Eustachian tube function requested from flying personnel today is generally regarded as acceptable if hearing and otoscopic findings are normal and there is no history of ear disease. Since increasing performance of modern aircrafts place more rigorous demands on the equilibrating capacity of the Eustachian tube and difficulty to clear the ears already is the most common cause of temporary grounding among flying personnel, the present requirements for tubal function might gradually get more and more inefficient. Inability to equilibrate in flight may lead to temporarily reduced hearing, acute ear pain and alternobaric vertigo that will affect the pilot's capacity and thus constitute a problem of flight safety. A testing procedure that makes it possible to continuously measure the middle ear pressure in subjects with intact eardrums during simulated flights in a pressure chamber would introduce a possibility to find basic medical standards of Eustachian tube function to be used in the selection of flying personnel. Student pilots, accepted for primary flight training, were examined in the present study by such a method. A comparison is made with the results of other tests of the Eustachian tube function in order to find out the relevance of the latter tests in the selection of flying personnel. The results are presented and discussed.

Adolescent↗
PubMed1984

Hearing threshold measurement in Menière's disease.

The hearing thresholds of 21 subjects with a typical history of Menière's disease on one side were determined four times by Békésy audiometry at fixed frequencies (250, 500, 1 000 and 2 000 Hz). The reliability of the hearing thresholds was calculated and no differences could be found between the Menière ear and the unaffected ear. A considerable increase in standard deviation of hearing thresholds could be noted if the middle ear pressure varied more than +/- 50 mm H2O between the tests. The results showed that with Békésy audiometry a 7-dB increase or decrease in hearing thresholds reflects a significant change in hearing in Menière's disease.

Adult↗
PubMed1983

Treatment with sulfur hexafluoride in children with serous otitis media. An alternative to tubulation.

In this pilot study, sulfur hexafluoride (SF6), a nontoxic inert gas infused into the ear during myringotomy and acting as a gas cushion behind an intact eardrum, was tested on five children with bilateral serous otitis media. The contralateral ear was treated with air as a control. A significant difference in air-bone gaps (frequencies, 0.5, 1.0, and 2.0 kHz) lasting at least eight weeks was found between the ears treated with SF6 and the air-treated ears. No side effects were noted. Tympanograms showed varying patterns. The long-term effects were also favorable for the SF6-treated ears. In selected cases, eg, ears with thin scars and retractions, this might be a valuable alternative to tubulation. Further studies are being carried out.

Acoustic Impedance Tests↗
PubMed1983

High speed tympanometry and ipsilateral middle ear reflex measurements using a computerized impedance meter. A comparison with the results obtained by a conventional impedance meter.

By means of a new computerized impedance meter, middle ear pressure, tympanograms and ipsilaterally elicited middle ear reflex can be recorded and presented in 3 sec. Owing to the fast rate of air pressure change in the external ear canal it is not necessary to have a completely airtight seal around the ear probe when recording middle ear pressure, which saves time. Results obtained using the new device and those obtained by a conventional impedance bridge are compared.

Acoustic Impedance Tests↗