During expiration, acini in lung base are assumed to empty first followed by those in the apex, thus producing the rising N2 alveolar plateau measured at the mouth This sequential emptying idea cannot simultaneously explain the shape of both the CO2 and N2 washout curves. It is well established that in healthy upright individuals during normal breathing the CO2 concentration is lower in the acini located in the apex of the lung less ventilated but far less perfused than in acini located in the base better ventilated and better perfused Sequential emptying in the same sequence as in the case of N2 washout, with the apex emptying last, would result in a CO2 washout curve recorded in the mouth with a downward-sloping alveolar plateau rather than the upward-sloping alveolar plateau that is almost always observed. In their paper on VCap in children23, postulated that the observed decrease in normalized phase 3 slopes of CO2 washout curves with increasing age was due to an increase in the interface between functional residual capacity FRC and tidal volume VT with lung growth in children. Apparently, taking into account the significantly smaller normalized values of phase 3 slopes in obese patients, a hypothesis can be put forward: obese patients may have larger or more efficient alveolated airspaces than non-obese subjects.
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Celize C. Almeida I ; Armando A. Ribeiro I ; Marcos T. Palavras-chave: Capnografia, espirometria, pediatria, asma. All of them underwent volumetric capnography and spirometry. All asthmatics repeated the tests after bronchodilator use. Among asthma patients, 33 underwent methacholine challenge test, and measures were recorded on three occasions: before and after methacholine and after bronchodilator use. After bronchodilator use, there was an increase in spirometric variables, volume of anatomic dead space, and decrease in the slope of phase II normalized by tidal volume, but the slope of phase III normalized by tidal volume did not change.
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Celize C. Almeida I ; Armando A. Ribeiro I ; Marcos T. Palavras-chave: Capnografia, espirometria, pediatria, asma. All of them underwent volumetric capnography and spirometry. All asthmatics repeated the tests after bronchodilator use.
Nos orgullece el contar con tantos clientes entregados y entusiastas. Bedside noninvasive detection of acute pulmonary embolism in critically ill surgical patients. Arch Surg ; 8 —; discussion — Partitioning of dead space — a method and reference values in the awake human. Eur Respir J.