Lung, Chest Wall, and Total Respiratory System Resistances and Elastances in the Normal Range of Breathing

Abstract

We measured total respiratory system and lung and chest wall resistances (Rrs, Rl, and Rcw) and elastances (Ers, El, and Ecw) in awake, relaxed human subjects during sinusoidal volume forcing at the mouth from 0.2 to 0.6 Hz with tidal volumes (VT) of 6 to 18% VC at constant mean airway pressure. In addition, we repeated measurements with the lowest VT at a lower airway pressure and therefore at a lower mean lung volume (Vl). Rrs and Rcw decreased with increasing respiratory frequency (f) and VT, but Rl was independent of f and VT. All resistances were higher at the lower Vl. Ers and Ecw increased with increasing f and decreased with increasing VT. El increased slightly with increasing f but was not affected by VT. All elastances tended to increase at the lower Vl. We conclude that in the normal range of breathing amplitude and frequency, (1) lung properties are nearly constant if mean lung volume does not change, and (2) f and VT dependencies of total respiratory system properties are caused by the chest wall.

Capnographic Parameters in Ventilated Patients: Correspondence with Airway and Lung Tissue Mechanics

“…Significant alteration in lung-thorax dynamics is expected to influence both the capnography indices and forced oscillatory data reflecting airway and tissue mechanics (35). The capnogram parameters are determined by the heterogeneity of the lungs, geometry of the airway tree and the forces exerted by the tissue resistive and elastic properties of the lungs and the chest wall (6).…”

Guidelines for mechanical lung function measurements in psychophysiology

“…FOT and interrupter technique both measure R rs , which includes additional resistances of lung and thoracic tissue. Table 1 shows summarized and rounded estimates for fractions of flow resistance from studies on healthy individuals, in which measurements were performed during spontaneous breathing through the mouth at FRC and V T in the sitting position~Bachofen, 1966; Barnas et al, 1992;Ferris, Mead, & Opie, 1964;Hantos, Daróczy, Suki, Galgoczy, & Csendes, 1986;Hyatt & Wilcox, 1961;Jaeger & Otis, 1964;McIlroy, Mead, Selverstone, & Radford, 1955!. 3 The estimates were obtained by different combinations of these techniques with more invasive methods such as the esophagus balloon catheter or pressure recording via a needle inserted into the extrathoracic part of the trachea. Most authors reported a considerable interindividual variation in estimates, probably due to anatomic differences.…”

Continuous on-line measurements of respiratory system, lung and chest wall mechanics during mechanic ventilation

“…The dynostatic alveolar P/V-curve describes the behaviour of this system during ongoing ventilator treatment. It therefore does not only represent its compliance but is also influenced by its dissipative and elastic components and inhomogeneities, which, in turn, depend on volume, flow and respiratory rate [13,17,18,19]. Thus, it is expected that it will show different features than the traditional static/semi-static methods.…”

“…These methods have only been used as research tools as they require substantial extra equipment and time for measurements and demand an abrupt change of the ongoing ventilator treatment to a special state of flow (no flow or low flow) not encountered during normal ventilator treatment. Such manoeuvres might alter respiratory mechanics from the properties during normal ventilator treatment as compliance and airway resistance are dependent on volume, flow rate and respiratory frequency [13,17,18,19]. We have recently presented a simplified method for measurement of oesophageal pressure (a surrogate for pleural pressure to calculate chest wall compliance) using a liquid-filled, doublelumen stomach tube [20] and the dynostatic algorithm for on-line, bedside calculation of a ªstaticº alveolar P/V-curve under dynamic conditions [21], based on direct measurements of tracheal pressure [22].…”