Biomedical subjects

A Barleben

Publications and source records attributed to A Barleben.

8 recordsLinked to original sources

PubMed1992

[Use of multi-frequency oscillation method in the respiratory mechanics perimeter diagnosis].

Oscillatory resistance Rrs and reactance Xrs curves were measured in the frequency range 4-25 Hz at FRC-level and at the course of vital capacity manoeuvres. The 55 subjects investigated were separated into the three groups healthy subjects and patients with restrictive and obstructive lung diseases by means of the parameters airway resistance Raw and lung compliance CL estimated by body-plethysmography and esophageal pressure technique, respectively. In accordance with the Raw- and CL-values in each group the parameters Rrs and Xrs demonstrate at FRC-level a different frequency dependent behaviour. An enhancement of Raw in patients with COLD causes a drop of Rrs(f) and a displacement of the whole Xrs-curve into the negative direction. Conversely, the reduction of CL in patients with fibrosis leads to a significant decrease of Xrs-values at lower frequencies without marked changes in the Rrs-curves. An additional enhancement of Raw and a further reduction of CL can be induced by decrease and increase of lung volume VL in comparison with the FRC-level. These alterations can be detected also in the frequency dependent shape of the Rrs- and Xrs-curves. Because of this inverse influence of VL on Raw and CL the diagnostic differentiation between patients with mild obstructive and restrictive lung diseases can be improved by a simultaneous evaluation of the volume and frequency dependence of oscillatory parameters.

Airway Resistance↗

PubMed1991

[Inspiratory phase angle behavior in oscilloresistometry].

Oscillatory measurement of resistance can get more practical relevance including the phase angle (PSI) and the volume dependence. Different findings during deep inspiration in patients with pulmonary emphysema (PSI unchanged) and with pulmonary fibrosis (PSI-Negativation) are known. To explain these findings transpulmonary pressure (Ptp) was measured parallel to PSI in 85 subjects. PSI-negativation was found in 31 of 43 patients with pulmonary fibrosis and in 10 of 19 healthy subjects. Patients with pulmonary emphysema have nearly constant or slight positive phase angles. Subjects with negativation of phase angle have significantly higher Ptp-levels at 100% TLC. This high pressure is reached by an in comparison to volume overproportional increase of pressure in the end part of the lung expansion curve. It is proposed to estimate the PSI-V-dependence in ranges from middle level of breathing to 75% of vital capacity VC and from 75% to 100% VC separately. By this modification the qualitative noninvasive assessment of lung compliance could be more efficient. Several findings indicate, that the observed secondary periodic of PSI are dependent from heart rhythm and therefore from intrathoracic blood volume.

Adult↗

PubMed1991

[Modification of inspiratory phase angle behavior in oscilloresistometry].

The diagnosis of pulmonary emphysema and fibrosis is possible by measuring the inspiratory behaviour of phase angle PSI of oscillation method. In addition to the different lung compliance as the main reason an influence of the shifting intrathoracical blood volume as the result of the pressure change is discussed especially for the appearing secondary PSI-periodic. Because a direct experimental evidence is not present in this study it was attempted to describe qualitatively the blood volume shift. Thoracic electrical impedance plethysmography and methods of nuclear medicine were used as methodological base. Although impedance plethysmography appears theoretical suitable and there are references, that alterations being independent from the heart rhythm may be detected, the originally aim of the study was not reached by the used method. The registration of radioactive labeled blood over the thoracical region by means of methods of nuclear medicine was applied as an alternative method. In contrast to the theoretical concept of a suction effect of the decreasing pressure during inspiration a decrease of the impulse rate and an increase of the latter during expiration was found. The reason could be the isolated registration of changes in the alveolar vessels. Possible secondary oscillations, which could be in relation with findings of lung mechanics, were not observed.

Adult↗

PubMed1990

[Lung function diagnosis using multi-frequency oscillometry with reference to lung volume].

The ranking of various oscillometry parameters was to be tested in patients with a broad spectrum of disturbances of pulmonary function, objectified by body plethysmographic and technical oesophageal pressure measurement of the respiratory resistance, lung volumes and lung elasticity. For this purpose the oscillatory resistance Rfo and the phase angle phi were measured at 8, 12 and 16Hz and phi was measured as it changed, depending on the lung volume V. It was found that enhanced respiratory resistance values are satisfactorily represented by Rfo for the purposes of preliminary and basic diagnostics. Besides, enhanced Rfo values are markedly dependent on the frequency, phi being shifted to negative values. Difference between Rfo values at 8 and 16 Hz (delta R8-16) less than 0.7 hPa/l/s phi greater than or equal to -10 degrees can be considered as being still normal with the employed measuring principle and are a valuable supplement for assessing the degree of obstruction. The difference between phi in the medium respiratory position and at 90 or 100% total capacity (delta phi) is less than 5 degrees during slow inspiration in 80% of the patients suffering from emphysema. In 80% of the persons with healthy lungs and those suffering from fibrosis there is an inspiratory negativation of phi (delta phi greater than 5 degrees) so that the phi-V relationship appear suitable for distinguishing patients with restricted vital capacity in respect of emphysema and fibrosis. Patients suffering fron fibrosis differ from healthy subjects by slightly more negative phi values. The borderline values for delta R8-16, phi and delta phi were confirmed in two further series of examinations on children and adolescents.

Adult↗

PubMed1989

Failure of ambroxol to influence the allergen induced bronchial constriction in sensitized guinea pigs.

The action of ambroxol was tested in an in vivo guinea pig asthma model. Ambroxol, a compound with antiallergic properties effects the mediator releasing cells in vitro and surfactant secretion from alveolar type II cells. This paper deals with the action of ambroxol in an in vivo asthma model in guinea pigs. Ovalbumin sensitized guinea pigs were artificially ventilated by negative chest wall pressure, using a tank respirator. Breathing parameters were measured pneumotachographically. The experimental animals were treated with 50 mg/kg ambroxol i.p. for 5 days; control animals received saline only. The results indicate that pretreatment with ambroxol had no significant effect on the allergic bronchial constriction, while in vitro ambroxol effects on mediator releasing cells and surfactant production point to antiallergic properties. An explanation of the failure of allergenic preventing effects of ambroxol in vivo may be its insufficient concentration in the tissue.

Allergens↗

PubMed1989

[Optimizing monofrequent oscillometry].

Against the background of the working hypothesis of the 1-parametric Siregnost FD 5 forced oscillation technique-phase angle psi may be invariant in a clinical reference population-the hypothetical straight Ros-P line is in good agreement with the crowd of extremely nonlinear Rre-P-lines only within narrow limits. Neglecting phase angle measurements it might be useful to insert a known linear resistor into the airway to determine the pertaining Rre-P relation. In spite of selective tuning to the oscillation frequency of 10 Hz there is full sensitivity to stationary flow; alinear stationary flow characteristics of resistors can be readily determined by forced oscillation. There is a marked improvement in the P-psi/Rre-phi-evaluating system with respect both to the symmetry of phase angle and unequivocality of pressure when the reference phase angle alpha is shifted from 81 degrees to 0 degrees. Using digital data acquisition and processing, a flexible evaluation technique with monitor-oriented test management, automatical calculation of secondary values and multidimensional presentation of results on a graphical display is provided, which has proved its worth in experimental and clinical-physiological studies.

Airway Resistance↗

PubMed1989

[Oscillometric differentiation of lung fibrosis and lung emphysema].

In three groups of healthy subjects and patients with pulmonary fibrosis or pulmonary emphysema, the secondary periodical oscillatory phenomena observed under conditions of normal breathing and a slow VC manoeuvre on the Siregnost FD 5 were broken down into a volume- and a flow-synchronous component, as also a third component with no correlation with either volume or flow, and which can be observed in the primary parameters Ros and psi, as also the secondary parameters Rre and phi. While both fibrotic patients and healthy subjects revealed a volume-inverse phase behaviour, patients with pulmonary emphysema revealed a volume-proportional phase behaviour. This difference in volume dependence is explained by the difference in elastic recoil in patients with fibrosis as compared with those suffering from emphysema, and the associated different influence on the filling of the lungs with air and blood.

Adult↗

PubMedDate not supplied

[A method of determining respiratory resistance by interrupting the air flow].

Air flow interruption was employed to check up the correctness of respiratory resistance measurements. The least scatter and minimum influence of muscle efforts perverting the alveolar pressure are obtained with pressure gained in the mouth after oscillations. Provided the resistance is computed in such a manner, the rate of the flow is measured before the interruption. It has been established that air flow interruption should be best performed during quiet respiration, at a rate approximating the maximum one, i.e. at about 0.5 l/s. To obtain sufficiently stable data, it is necessary to derive the mean value from several (at least 5) respiratory cycles.

Airway Resistance↗