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Biomedical subjects

O Tjernström

Publications and source records attributed to O Tjernström.

At least 37 records · Page 2Linked to original sources
PubMed1983

Physiological and behavioral effects of tilt-induced body fluid shifts.

This paper addresses the "fluid shift theory" of space motion sickness. The primary purpose of our research was the development of procedures to assess individual differences in response to rostral body fluid shifts on earth. Experiment I examined inner ear fluid pressure changes during head-down tilt in intact human beings. Tilt produced reliable changes. Differences among subjects and between ears within the same subject were observed. Experiment II examined auditory threshold changes during tilt. Tilt elicited increased auditory thresholds, suggesting that sensory depression may result from increased inner ear fluid pressure. Additional observations on rotation magnitude estimation during head-down tilt, which indicate that rostral fluid shifts may depress semicircular canal activity, are briefly described. The results of this research suggest that the inner ear pressure and auditory threshold shift procedures could be used to assess individual differences among astronauts prior to space flight. Results from the terrestrial observations could be related to reported incidence/severity of motion sickness in space and used to evaluate the fluid shift theory of space motion sickness.

Adolescent↗
PubMed1982

Reliability in tests of the eustachian tube function.

With the aid of a quantitative impedance method and a pressure chamber, the capacity of the Eustachian tube to equilibrate pressure differences across the tympanic membrane was repeatedly determined in 20 otologically healthy men. The test-retest reliability was calculated from five determinations of static pressure equilibration of over- and underpressures of 10 cmH2O and 10 determinations of equilibration of dynamic pressure changes. The pressure opening level of the tube during pressure increase in the middle ear was significantly lowered in the initial determinations. The residual pressure in the middle ear after maximum equilibrating efforts during pressure increase in the chamber was also significantly lowered. For the rest, the test-retest reliability was good. Ears with perfect tubal function had better test-retest reliability for all parameters tested than ears with poorer function. The significance of repeated measurements and the value of reliability determinations are discussed.

Acoustic Impedance Tests↗
PubMed1981

Comparison of Eustachian tube function measured by the microflow method and a new quantitative impedance method.

Eustachian tube function in 25 applicants for flight training was tested during simulated flights using two methods alternately; the integrating microflow method with a stationary pressure chamber, and a new quantitative impedance method in combination with a new mobile pressure chamber. All ears were tested by both methods. The results of the various tests did not differ significantly between methods. The reliability of the measurements was good and almost equal in both methods. Several practical advantages with the new impedance method in combination with the mobile pressure chamber make it preferable.

Acoustic Impedance Tests↗
PubMed1980

Prospective evaluation of vestibular and auditory function in 76 patients treated with netilmicin.

Seventy-six patients were included in a prospective study in order to assess the ototoxicity of netilmicin. Netilmicin. Netilmicin was administered intramuscularly with a dosage of 1.5 mg/kg body weight 2 or 3 times daily. The dosage was modified in cases with even slight renal insufficiency. Vestibular and auditory function was examined by electronystagmography (ENG) and audiometry before and during therapy, 1 week and 2-3 months after completion of therapy. Drug-related VIIIth nerve toxicity--vestibular dysfunction--was suspected in one case. However, this dysfunction was subclinical and reversible. The importance of pretreatment evaluation was obvious as an ototoxic damage might have been suspected in 14 patients if the pretreatment examination of vestibular and auditory function had not been performed. Clinical ototoxicity of netilmicin seems to be low when careful attention is paid to the renal function and the serum concentrations of the drug.

Adolescent↗
PubMed1980

Eustachian tube function in selection of airmen.

A comprehensive study of Eustachian tube function in 84 aspirants accepted for flight training was made. Using a pressure chamber, both static and dynamic pressure changes, as in ascent and descent, were applied to test the tubal pressure equilibrating capacity in the sitting position. While all 84 were otologically healthy, a wide range in the pressure equilibrating capacity was found--20% could not equilibrate static over- and underpressures of 10 cm H2O completely, 8% could not equilibrate at all during simulated descent, 3 subjects reported acute vertigo during simulated ascent in combination with high unilateral middle ear pressure. Asymmetry between ears of single subjects in pressure equilibrating capacity was also found to a large extent. It was not possible to identify subjects with poor equilibrating capacity by simple tests like Valsalva's or Toynbee's manoeuvres. The results may indicate that today's criteria for Eustachian tube function in the selection of airmen can be made more efficient.

Adolescent↗
PubMed1980

Effects of different body positions on the Eustachian tube function in the selection of airmen.

The Eustachian tube function of 52 applicants accepted for flight training had earlier been comprehensively tested during simulated flights in a pressure chamber in the sitting position. Despite the fact that all were otologically healthy, the wide range of pressure-equilibrating capacity in the sitting position was even more pronounced when they were rested in recumbency, and in every type of test the pressure-equilibrating capacity was reduced. For instance, 17% of the recumbent subjects could not equilibrate at all during simulated descent as compared to 8% in the sitting position; 81% of the ears were Toynbee positive in the sitting position and only 69% in recumbency. The advantages of the recumbent compared to the seated test position are discussed.

Aerospace Medicine↗
PubMed1980

Current status of pressure chamber treatment.

Forty-five patients with unilateral and one patient with bilateral Meniere's disease were exposed to underpressure in a pressure chamber during an acute attack that was primary in 24 and recurrent in 23. The patients were instructed to avoid active equilibration during reduction of the pressure, in order to induce an overpressure in the middle ear. Treatment was promptly followed by improvement of hearing in 20 patients (21 ears) and by a remission for more than three years in seven cases. No side effects were observed. We therefore believe that this procedure may be useful in the prevention of damage to the cochlear hair cells with secondary permanent loss of hearing.

Atmospheric Pressure↗
PubMed1979

Hearing improvement in attacks of Meniere's disease treated with pressure chamber.

A method to reduce endolymphatic pressure by exposing patients with Meniere's disease to underpressure has earlier been described. In this work the possible mechanisms are discussed. A material of 36 patients with acute attacks, treated in this way, is now presented. 15 out of these patients experienced a rapid hearing improvement. In 11 cases the remission has lasted for more than 1 year. The method seems to be of great value for those who improved, since at least an early permanent damage to the cochlea can be avoided.

Atmosphere Exposure Chambers↗
PubMed1979

Netilmicin: clinical evaluation of efficacy and toxicity of a new aminoglycoside.

The efficacy and toxicity of netilmicin, a new semisynthetic aminoglycoside, was clinically evaluated in fifty-two patients with moderate to severe infections with Gram-negative rods or Staph. aureus. Average duration of treatment was 14 days and mean total dose 2,960 mg. One-hour mean value of netilmicin serum concentration was 6.4 microgram/ml and mean trough value 1.2 microgram/ml. Forty-four patients were cured or improved. In twenty-one of them the effect could be attributed to netilmicin alone; the other twenty-three had a combined therapy. No improvement took place in five, but four of them could not be regarded as netilmicin failure. One patient with Pseudomonas aeruginosa infection was possible failure. The sensitivity of the causative bacteria to netilmicin was studied and compared with amikacin, gentamicin, sisomicin and tobramycin. Vestibular function and hearing acuity was thoroughly examined by electronystagmography and audiography. Drug-related VIIIth nerve damage could not be confirmed in any of our patients. Five patients showed a rise of serum creatinine of 30 mumol/l. This shows that netilmicin, similar to other aminoglycosides, is a potential nephrotoxic drug. Netilmicin appears to be an efficacious aminoglycoside and the oto- and nephrotoxicity is low, if careful attention is paid to the renal function and the serum concentrations of the drug.

Adolescent↗
PubMed1976

Isolated temporary pharyngeal paralysis in childhood.

Three children developed dysphagia and rhinolalia indicating isolated paralysis of the ninth and tenth cranial nerves. They recovered completely after three to four weeks. The clinical features suggested an infectious aetiology.

Brain Injuries↗