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Biomedical subjects

A Ivarsson

Publications and source records attributed to A Ivarsson.

At least 91 records · Page 5Linked to original sources
PubMedDate not supplied

A new impedance method for measuring middle ear mechanics and eustachian tube function.

The main principle of this new impedance method is a continuous recording of changes in tympanic membrane compliance in relation to its neutral position during changes in pressure, using a small pressure chamber. The subject sitting in the chamber can be placed in the recumbent position by rotation of the chamber. The working principles of the impedance method are: a servosystem regulates displacement of the loudspeaker membrane in order to keep the sound pressure in the external ear canal constant, independent of tympanic membrane compliance. From this recording it is possible to isolate tympanic membrane compliance during changes in intratympanic pressure as well as during ambient pressure changes. The results indicate that the new regulated impedance method combined with the small pressure chamber should be useful in routine clinical examination of middle ear mechanics and eustachian tube function.

Acoustic Impedance Tests↗
PubMedDate not supplied

Immediate restoration of basal sensorineural hearing (Mb Meniere) using a pressure chamber.

A new technique for the restoration of basal sensorineural hearing loss in Mb Meniere was described. Three cases with unilateral basal sensorineural hearing loss, fullness of the ear, and tinnitus were reported. In the acute stage of their disease the patients were treated in a pressure chamber where it was possible to increase or decrease the air pressure within the range +/- 110 cm H2O. The equilibration of middle ear pressures to surrounding air pressures was checked. Exposure to underpressure resulted in a rise of the hearing thresholds at low frequencies and relief of subjective symptoms. When the air pressure was increased the hearing thresholds were lowered and the sensation of tinnitus and fullness of the ear was accentuated. Changes in air pressure did not affect the healthy ears or the high frequencies in the diseased ear. Hearing improvement attained at exposure to underpressure seemed to remain at atmospheric pressure level. The investigation was performed on the hypothesis that a distended membranous labyrinth might cause a venous congestion of the vestibular aqueduct, resulting in impaired endolymph absorption in the endolymphatic sac. Possible effects of changes in environmental air pressure on the inner ear were discussed.

Adult↗
PubMedDate not supplied

Pressure-dependent variation in volume of mucosal lining of the middle ear.

A method is described for studying pressure-dependent variation in the volume of the mucosa of the middle ear. Studies were performed at different pressures in the middle ear as well as at different ambient pressures. It was found that the pressure-dependent volumetric changes of the mucosa were the same whether the pressure in the middle ear was changed directly by altering the intratympanic or indirectly by altering the ambient pressure. With the method described it is also possible to determine the middle ear volume without artefacts due to the middle ear mucosa. The volume-pressure relationship of the middle ear mucosa varied from 0.6 to 1.7 mul/cm H2O and linearly with the volume of the middle ear. Comparisons between determinations of the middle ear volume with and without consideration of the mucosal compliance showed differences, especially in small middle ears. The effect on the volume of the mucosa caused by variation of posture was also studied. The physiological middle ear pressure depends on the functional state of the Eustachian tube, the middle ear volume, the tympanic membrane and the middle ear mucosa. Thus, knowledge of the mucosa compliance is important for calculating middle ear pressure as well as for determining the volume of the air-filled middle ear space. The method might also prove a useful tool in the elucidation of the vascular bed both in health and in disease as well as the reaction of the mucosal vessels to drugs.

Atmospheric Pressure↗
PubMedDate not supplied

On tubal function in presence of central perforation of drum in chronic otitis media. Clinical methods and preoperative analyses - 132 cases.

Opinions differ on the value of preoperative testing of tubal function. The results vary widely, but so far no comparative investigation between different tubal function tests seems to have been published. On 132 ears with central tympanic perforation, 9 of which were traumatic and the remaining following chronic otitis media, tubal function was studied with a closed manometric method and open flow volume method which measures the tubal volume passage. The results of the closed and open techniques agreed in 96%. The open method is more sensitive, but the closed method is easier. 70% of the total material had aspiration capacity, i.e. could neutralise middle ear pressures, which is better than earlier results. Toynbee's test is a good screening test and when positive, it means good tubal function. A close correlation was found between tubal function and the volume of the air cell system as an effect of the systemic mucosal damage.

Adolescent↗
PubMedDate not supplied

Immediate relief of symptoms during acute attacks of Meniere's disease, using a pressure chamber.

Five patients with Meniere's disease were exposed to underpressure in a pressure chamber while suffering from acute attacks with vertigo, nausea, tinnitus and fullness of the ear. Spontaneous nystagmus was the objective criterion for the selection of suitable cases. Subjective as well as objective symptoms subsided much faster than they do with other kinds of treatment. Four patients were free from symptoms within 40 minutes, while the fifth case still complained of vertigo, tinnitus and fullness of the ear after the treatment. However, the symptoms were less severe. A mechanism is discussed by means of which an ambient pressure decrease might cause a reduction of the endolymphatic volume, thus relieving acute symptoms of Meniere's disease.

Acute Disease↗
PubMedDate not supplied

Volume-pressure properties of round and oval windows. A quantitative study on human temporal bone.

A model study was carried out on human temporal bones to assess quantitatively the displacement of the round and oval windows when different pressure levels were applied to the external ear canal and inside the middle ear. It was found that the major displacements of the window membranes occurred in the pressure range of +/- 20 cm H2O in the intact middle ear. An additional increase in the middle ear pressure up to +/- 70 cm H2O caused a minor displacement of the window membranes.

Aged↗
PubMedDate not supplied

The influence of perilymphatic pressure on the displacement of the tympanic membrane. A quantitative study on human temporal bones.

A model study on human temporal bones was performed. A microflow method was used in order to assess the possibility of making indirect recordings of changes in the inner ear pressures. Changes in the perilymphatic pressure were recorded as displacements of the tympanic membrane, the stapedius reflex being artificially elicited by forces applied briefly to the stapedius tendon. Changes in the perilymphatic pressures in the range of +/-15 cm H2O affected the position of the tympanic membrane and the "stapedius reflex response". The microflow method used seems suitable for the clinical recording of changes in the intralabyrinthine pressure.

Adult↗
PubMedDate not supplied

Volume displacement of the tympanic membrane in the sitting position as a function of middle ear muscle activity. A quantitative microflow method.

An open microflow meter system has been worked out for quantitative recording of the volume displacement of the tympanic membrane and its movement direction at stapedius reflex. An acoustically elicited M. stapedius contraction can be recognized by the characteristic response and latency time. The stapedius reflex contraction causes an outward or inward movement of the tympanic membrane. The magnitude of the volume displacement of the tympanic membrane is influenced by the middle ear pressure and in some ears the movement direction of the tympanic membrane changes.

Adult↗
PubMedDate not supplied

Volume displacement of the tympanic membrane at stapedius reflex activity in different postures. Studies on variations in perilymphatic pressure.

With the microflow method the volume displacement of the tympanic membrane and its direction of movement can be recorded at stapedius reflex contraction. There is an outward or inward movement of the tympanic membrane, which is affected by changes in posture. The results indicate that the perilymphatic pressure in man varies with the posture and that these variations can be measured indirectly outside the tympanic membrane. This can only be done, however, on condition that there are no pressure variations across the tympanic membrane. This method opens up new ways of studying possible pressure changes in the inner ear in acute diseases.

Auditory Threshold↗
PubMedDate not supplied

Pulse volume recordings in outer ear canal in pulse synchronous tinnitus. A comparison between ears with Glomus tumour, serous otitis media, and normal ears.

With the aid of a volume flowmeter it is possible to record pulse synchromous volumetric changes in the outer ear canal. In 7 ears with glomus tumour in the tympanic cavity and in 5 with serous otitis media, such changes were larger than in 125 persons with a normal middle ear. By changing the ambient pressure in a pressure chamber and instructing the patients not to swallow, the drum can be pushed inward or outward. In all the cases of glomus tumour studied the pulse volumetric change was considerably affected when the drum was pushed inward or outward. In the normal patients the change was no change at all. This means that the pulse volume changes in normals are generated mainly by the vessels in the outer ear canal.

Adolescent↗
PubMedDate not supplied

The elastic properties of the tympanic membrane system in divers and non-divers.

The volume/pressure relationship of the tympanic membrane system was studied in 24 scuba divers. The results were compared with the results obtained from 98 non-diving subjects. Among persons with a good function of the Eustachian tube, divers had an increased mobility of the tympanic membrane system as compared to non-diving subjects. Divers with a reduced function of the Eustachian tube did not differ from the non-diving subjects with a reduced tubal function. Factors that might influence the volume/pressure relationship of the tympanic membrane system are discussed.

Adult↗
PubMedDate not supplied

The effect of static middle ear pressures on the hearing threshold.

The effect of static tympanic pressure gradients on hearing sensitivity was studied by introducing relative underpressure of 5, 10 and 15 cmH2O in the middle ear cavity of six normal ears. A self-recording Békésy audiometer was used to measure the hearing threshold shifts during middle ear pressure equilibrations. The threshold loss was most prominent for 0.5 and 1 kHZ and less for 4 kHZ. A threshold gain was shown for 2 and 6 kHZ. Over all test frequencies the threshold shifts were increased with higher relative underpressure in the middle ear cavity. In order to evaluate the hearing impairment caused by noise, it is therefore important to control the middle ear pressure before hearing is tested. A small change in middle ear pressure can be ignored when using the summed hearing thresholds between 2 and 8 kHZ.

Audiometry, Pure-Tone↗
PubMedDate not supplied

Eustachian tube function in normal children and adults.

Eustachian tubal function was studied in 85 otologically healthy children, 3-12 years of age. Middle ear pressure and muscular opening function was measured by tympanometry performed in a pressure chamber, and the results were compared with those obtained from 92 normal adults. Children were found to have a less good muscular opening function and more negative middle ear pressures within wider ranges, compared with adults. Improvement was also seen in children with increasing age. The results seemed to indicate a relation between muscular opening function and middle ear pressure. Even if it were possible to grade the muscular opening function by means of the test procedure, it would still not be possible to define what should be regarded as normal or abnormal tubal function. This report is the first in a series of tubal function studies in normal children.

Acoustic Impedance Tests↗
PubMedDate not supplied

Rhinomanometry. I. Simple equipment.

A rhinomanometer for clinical work and research is presented. It adheres to the principle that pressure and flow should be recorded X-Y wise. A storage oscilloscope is used and the tracing pencilled down on a preprinted diagram via an oscillotracer. Anterior and posterior rhinomanometry can be performed. In the former variety, one nostril is occluded and connected to the pressure transducer by an adhesive tape. This does not deform or irritate the nasal airway. A mask for anaesthesia connects the nose to the pneumotachograph. Miniature transducers mounted on the pneumotachograph provide mechanical advantages. Simple means that allow dynamic calibration of the rhinomanometer are described. The cost to set up and operate the equipment is low.

Airway Resistance↗
PubMedDate not supplied

Pressure opening and closing functions of the eustachian tube in children and adults with normal ears.

Eustachian tube function was studied with the impedance technique and a pressure chamber in 58 children, aged 3-12 years, and 61 adults, aged 17-73 years, all otologically healthy. The pressure opening and closing functions were measured, i.e. the relative overpressure in the middle ear required to force open the tube, and the residual overpressure in the middle ear after pressure opening, respectively. These "passive" functions of the tube, assumed to reflect the closing factors, did not differ significantly between normal children and adults. The muscular opening function, i.e. "active" pressure equilibration capacity, on the other hand, was significantly poorer in children than in adults and poorer in younger children than in older ones. The results can be used as a reference material in investigations of the Eustachian tube in children with middle ear disease.

Adolescent↗
PubMedDate not supplied

Pressure opening and closing functions of the Eustachian tube by inflation and deflation in children and adults with normal ears.

Different inflationary (e.g. Valsalva's) and deflationary (e.g. sniffing) manoeuvres were studied in 58 children and 61 adults, all otologically healthy, in order to evaluate qualitatively and quantitatively the pressure opening and closing functions of the Eustachian tube. Only 71% of the normal children could voluntarily increase the middle ear pressure compared with 100% of the adults. The corresponding figures for evacuating the middle ear by deflation were 24% and 34%, respectively. The rhinopharyngeal pressure levels during the manoeuvres were age-dependent and decided the response rate in children. Tubal factors also determined the response rate since low pressure opening and closing levels were related to successful deflation. Negative middle ear pressures found in the normal children were due to poor muscular opening function of the tube rather than successful deflation. The pressure closing level seems to be a reliable tool in grading tubal closing ability.

Adolescent↗
PubMedDate not supplied

Patency tests of the maxillary ostium--model experiments.

The function of the maxillary ostia (phi 0.22-4.7 mm) has been evaluated in experiments on a nose-sinus model with variable sinusal volumes. A piston-pump producing to-and-fro volumes of 467 cm3 of air per revolution was used at a speed of 10 and 20 revolutions per minute (rpm). Three different techniques were used: simultaneous pressure recording in the sinus and the nose (Method I); simultaneous recording of the differential pressure between nose and sinus and the air-flow through the ostium (Method II); recording of the pressure rise inside the sinus upon the application of a constant artificial air-flow of 16,7 cm3 . s-1 or 2.0 cm3 . s-1 (Method III). All variables were recorded on an ink-jet recorder and onto tape when using methods I and II for later analysis on an x-y recorder. A pressure relationship of 1 : 1 was found between nose and sinus, independently of ostial diameters, sinusal volumes and piston-pump rates. The first method did not permit an isolated determination of the ostial function as the pressure values recorded are affected by ostial diameters, sinusal volumes and piston-pump rates. The pressure-flow relationship recorded with the second method was found to be dependent only on the ostial diameters. Hysteresis was observed at ostial diameters less than or equal to 1.63 mm. This is due to ostial diameter, sinusal volume and the rate of the nasal pressure changes. This method is suitable for an isolated determination of the ostial resistance, from which the equivalent ostial diameter can be calculated. With the third method using static air-flows and pressures the results are independent of the sinusal volume. This method is suitable for estimation of the ostial airway resistance and the equivalent ostial diameter. A striking similarity was observed between the results obtained with the last two methods in estimating equivalent ostial diameters.

Airway Resistance↗