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Effect of dimensions of airways and posture on respiratory impedance
Abstracts-International Society of Biomechanics XIV Congress 1993
859
AND POSTURE ON RESPIRATORY IMPEDFINCE DIMENSIONS OF AIRWAYS D’yachenko Institute of Biomedical Problems, Moscow, Russia The objective of this study was a modeling of effect of dimensions of airways on respiratory impedance. By means of a model we analyzed possible reasons of measured postural changes af respiratory mechanical properties in humans in the frequency range 7-19 Hz. In a model we considered a symmetrically branching airway structure with yielding walls. Lengths and diameters of airways are supposed to be proportional to a lung volume in the power of one third. Respiratory system resistance in the model increased, inertance and elastance decreased with decreasing lung volume. In our experimental studying of oscillatory mechanics of the respiratory and elastance were 50 %. 50 % and 62 % inertance system resistance, respectively larger in supine position than in sitting position. On the theoretical data one can conclude that a basis of the experimental and proportional decrease of airways dimensions caused by reduction in lung volume of 25 % in supine position can be a significant but not single cause of an increase in respiratory resistance. The increase in inertance and a part of the increase in resistance in a supine position can be related to an additional compression of airways. The increase of elastance is an evidence of changes in mechanical properties of respiratory tissues. EFFECT Cllexander
OF
3D -TIC ANALYSIS OF RESPIRATORY MOVJBlENTS G.Ferrigno1v2,F.Molteni:, P.Camevali’ and A.Aliverti’ 1 - Centro di Bioingegnena - Pro JuventuteFnd. I.R.C.C.S. - Politecnico di Milan0 2 - Dipartimento di Bioingegneria - Politecnico di Milan0 - Italy 3 - OspedaleVaIduce - Como - Italy Kinematic analysis of rib cage and abdominal walls volume changesduring breathing allows a biomechanic anal@ of the dynamic interaction between muscularventilatory pump and passivestructural componentsof the respu-atorysystem and the study of breathing act execution strategies. The method here propow! is baud or! an automatic motion analyser, the ELITE system, which measuresthe 3-D co-ordinatesof several markers applied to body landmarks. The markers are small hemispherescoated with retro-reflective paper. The co-ordinates of the landmarks are measuredwith a systemconfiguration with four TV-cameras at 100 Hz of sampling rate. Two different experimental set-up have been considered,for sitting and supine subject position. In the sitting one the subjectwears 32 markers, arranged on an anterior four by four frame and a posterior specularon:; in the supine position the posterior frame is not acquired becausethe back is supposedto lay on the bed. Starting from these co-ordinatesthe thoracoabdominalvolume is computed by using a model of the body which allows the computation either of the contribution to ventilation due to upper thorax, lower thorax and abdomenor the one due to left, central or right trunk. The set-up has been testedon 12 healthy subjects. After the validation on healthy subjects, the method has been applied to the study of breathing pattern of pathological subjects, in particular to neuromuscularones. The proposed method can be considereduseful for the optimization of the assistedventilation in order to provide the more physiological behaviour of the respiratory involved districts, allowing an optimal matching between lung ventilation and perfusion.
CLINICAL MEASUREMENT OF AIRWAY AREA PROFILE BY A NEW ACOUSTIC REFLECTION METHOD. Bruno Louis*, Jeffrey J. Fredberg* and Daniel ISABEY** *The Biomechanics Institute and Harvard School of Public Health, Boston, MA 02215, USA ** Institut National de la Sante Et de la Recherche MCdicale, U.296, Cr&eil, 94010, France. This paper deals with a non-invasive assesment of airway dimensions from acoustic reflection data measured at the mouth. The new approach is based upon a dual transducer system. Unlike the single transducer system currently used, this new approach permits a miniaturization of the apparatus as well as a broader range of potential clinical applications. Experiments in a glass tube model with the dual transducer system were closely in agreement with a water displacement method and with the current one microphone method. We also present a new algorithm permitting accurate estimation of tracheal area without using an He-O2 mixture which had been previously thought necessary. The validity of such a simplification of the acoustic method is confirmed by preliminary results obtained in humans. Indeed, these results showed a clear similarity between acoustic airway profiles obtained (i) in He-02, with the one transducer system taken as the reference method, and (ii) in air, with the new dual transducer system proposed in this study. Bn 27:6-P
859
AND POSTURE ON RESPIRATORY IMPEDFINCE DIMENSIONS OF AIRWAYS D’yachenko Institute of Biomedical Problems, Moscow, Russia The objective of this study was a modeling of effect of dimensions of airways on respiratory impedance. By means of a model we analyzed possible reasons of measured postural changes af respiratory mechanical properties in humans in the frequency range 7-19 Hz. In a model we considered a symmetrically branching airway structure with yielding walls. Lengths and diameters of airways are supposed to be proportional to a lung volume in the power of one third. Respiratory system resistance in the model increased, inertance and elastance decreased with decreasing lung volume. In our experimental studying of oscillatory mechanics of the respiratory and elastance were 50 %. 50 % and 62 % inertance system resistance, respectively larger in supine position than in sitting position. On the theoretical data one can conclude that a basis of the experimental and proportional decrease of airways dimensions caused by reduction in lung volume of 25 % in supine position can be a significant but not single cause of an increase in respiratory resistance. The increase in inertance and a part of the increase in resistance in a supine position can be related to an additional compression of airways. The increase of elastance is an evidence of changes in mechanical properties of respiratory tissues. EFFECT Cllexander
OF
3D -TIC ANALYSIS OF RESPIRATORY MOVJBlENTS G.Ferrigno1v2,F.Molteni:, P.Camevali’ and A.Aliverti’ 1 - Centro di Bioingegnena - Pro JuventuteFnd. I.R.C.C.S. - Politecnico di Milan0 2 - Dipartimento di Bioingegneria - Politecnico di Milan0 - Italy 3 - OspedaleVaIduce - Como - Italy Kinematic analysis of rib cage and abdominal walls volume changesduring breathing allows a biomechanic anal@ of the dynamic interaction between muscularventilatory pump and passivestructural componentsof the respu-atorysystem and the study of breathing act execution strategies. The method here propow! is baud or! an automatic motion analyser, the ELITE system, which measuresthe 3-D co-ordinatesof several markers applied to body landmarks. The markers are small hemispherescoated with retro-reflective paper. The co-ordinates of the landmarks are measuredwith a systemconfiguration with four TV-cameras at 100 Hz of sampling rate. Two different experimental set-up have been considered,for sitting and supine subject position. In the sitting one the subjectwears 32 markers, arranged on an anterior four by four frame and a posterior specularon:; in the supine position the posterior frame is not acquired becausethe back is supposedto lay on the bed. Starting from these co-ordinatesthe thoracoabdominalvolume is computed by using a model of the body which allows the computation either of the contribution to ventilation due to upper thorax, lower thorax and abdomenor the one due to left, central or right trunk. The set-up has been testedon 12 healthy subjects. After the validation on healthy subjects, the method has been applied to the study of breathing pattern of pathological subjects, in particular to neuromuscularones. The proposed method can be considereduseful for the optimization of the assistedventilation in order to provide the more physiological behaviour of the respiratory involved districts, allowing an optimal matching between lung ventilation and perfusion.
CLINICAL MEASUREMENT OF AIRWAY AREA PROFILE BY A NEW ACOUSTIC REFLECTION METHOD. Bruno Louis*, Jeffrey J. Fredberg* and Daniel ISABEY** *The Biomechanics Institute and Harvard School of Public Health, Boston, MA 02215, USA ** Institut National de la Sante Et de la Recherche MCdicale, U.296, Cr&eil, 94010, France. This paper deals with a non-invasive assesment of airway dimensions from acoustic reflection data measured at the mouth. The new approach is based upon a dual transducer system. Unlike the single transducer system currently used, this new approach permits a miniaturization of the apparatus as well as a broader range of potential clinical applications. Experiments in a glass tube model with the dual transducer system were closely in agreement with a water displacement method and with the current one microphone method. We also present a new algorithm permitting accurate estimation of tracheal area without using an He-O2 mixture which had been previously thought necessary. The validity of such a simplification of the acoustic method is confirmed by preliminary results obtained in humans. Indeed, these results showed a clear similarity between acoustic airway profiles obtained (i) in He-02, with the one transducer system taken as the reference method, and (ii) in air, with the new dual transducer system proposed in this study. Bn 27:6-P