TY - JOUR T1 - Putting noninvasive lung mechanics into context JF - European Respiratory Journal JO - Eur Respir J SP - 1435 LP - 1437 DO - 10.1183/09031936.00093413 VL - 42 IS - 6 AU - Peter M.A. Calverley AU - Ramon Farre Y1 - 2013/12/01 UR - http://erj.ersjournals.com/content/42/6/1435.abstract N2 - Anyone who teaches medical students about how the lungs work meets an immediate problem. The best way to describe the mechanics of breathing is in terms of airways resistance and lung compliance but these measurements are not readily available in clinical practice. Instead clinicians focus on the indirect information available from spirometry. The great advantage that spirometry offers is its known immediate reproducibility and limited between test variation in both health and disease [1]. These properties, coupled with its extensive use in clinical decision making, ensure that spirometric measurements are going to be used in managing respiratory disease for the foreseeable future. One particular advantage of spirometry is the availability of age- and height-related normal values against which any recording can be judged [2].From the 1950s onwards, physiologists realised that applying small multi-frequency pressure oscillations at the mouth would produce changes in volume and flow that provided a direct and noninvasive measurement of respiratory system mechanics. These data were expressed in terms of respiratory system resistance and reactance (the latter a complex concept involving negative numbers that has never appealed to clinicians), and should give an insight into how breathing at rest is related to disease. To make this measurement clinically practical there had to be substantial improvements in the accuracy of the pressure transducers which measured the very small fluctuations in pressure, and hence flow, within the airways and also a considerable increase in the computing power necessary for the complex mathematical manipulations, such as fast Fourier transformations which disentangle the mixture of frequencies applied to describe the behaviour of the respiratory system. By the early 1980s [3] these developments had become a reality and a number of researchers, especially those based in Belgium, made measurements of resistance and reactance in healthy … ER -