Effective Respiratory System Elastance During Positive-Pressure Breathing in Supine Man

Josenhans, W. T.; Peacocke, T. A.; Schaller, Georg

doi:10.1097/00132586-197702000-00002

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“…Indeed, when the position of the muscle force application point is at the bottom end of the dashpot, this results in parallel changes in RC and A signals, in other words a very low phase difference, inducing indecision in the multiple linear regression calculation (badly conditioned matrix). On the other hand, elastances are greatly influenced by thoracic muscle tone which may vary in the course of the breath (Josenhans et al 1975). This may impair the adequacy of the model which relies on the hypothesis that elastances are constant.…”

Section: Discussionmentioning

confidence: 99%

A Simple Dynamic Model of Respiratory Pump

et al. 2010

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To study the interaction of forces that produce chest wall motion, we propose a model based on the lever system of Hillman and Finucane (J Appl Physiol 63(3):951-961, 1987) and introduce some dynamic properties of the respiratory system. The passive elements (rib cage and abdomen) are considered as elastic compartments linked to the open air via a resistive tube, an image of airways. The respiratory muscles (active) force is applied to both compartments. Parameters of the model are identified in using experimental data of airflow signal measured by pneumotachography and rib cage and abdomen signals measured by respiratory inductive plethysmography on eleven healthy volunteers in five conditions: at rest and with four level of added loads. A breath by breath analysis showed, whatever the individual and the condition are, that there are several breaths on which the airflow simulated by our model is well fitted to the airflow measured by pneumotachography as estimated by a determination coefficient R(2) > or = 0.70. This very simple model may well represent the behaviour of the chest wall and thus may be useful to interpret the relative motion of rib cage and abdomen during quiet breathing.

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Section: Discussionmentioning

confidence: 99%