Source: Annual Congress 2002 - Lung mechanics: from laboratory to bedside
Disease area: Respiratory critical care

Abstract

The elastic pressure volume, Pel/V, curve is important in diagnostics of lung disease. To evaluate bronchial pathology resistance, R, must be related to Pel and flow, as done with the flow regulator method (1) in which the square flow pulses cause noise. In mechanical ventilation sinusoidal insufflation allows studies of resistance and Pel/V curves(2). We describe sinusoidal modulation of voluntary expiration for studies of Pel/V and Pel/R curves.
Method: Pleural pressure relative to mouthpiece pressure, Ppl, and flow were measured during expiratory vital capacity manoeuvres in a body box for measurement of lung volume. A computer controlled valve modulated flow. Pel/V and Pel/R diagrams were iteratively calculated from measured pressure, flow and volume (2).

Results: In 20 healthy subjects Pel/V curves from square and sinusoidal flow agreed. Some differences with respect to R reflect difficulties to measure low R with any method.
1. Jonson B. Scand J Clin Lab Invest 1969,24,115-125
2. Jonson B et al. Am J Respir Crit Care Med. 1999,159,1172-1178

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Citations should be made in the following way:
U. Bitzén, L. Niklason, B. Drefeldt, I. Göransson, B. Jonson (Lund, Sweden). Lung mechanics studied with sinusoidal modulation of expiratory flow. Eur Respir J 2002; 20: Suppl. 38, 185

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