[Value of non-plethysmographic methods in determining airway resistance]

To examine whether the complicated method of body plethysmography can be replaced by non-plethysmographic methods, such as oscilloresistometry (Ros), the closing pressure method (Run) or the forced expiration volume method (FEV1), the authors studied the results obtained with 247 hospitalised patients between 18 and 81 years of age suffering from, or free from, airway obstruction. Although satisfactory correlations were obtained by linear and curvilinear regression analysis, considerable differences were seen in individual patients suffering from obstructions to a higher degree. Oscilloresistometry showed at the standard value limit of the airway resistance applicable in body plethysmography (0.30 kPa/l/s) a sensitivity of 89%, whereas the specificity was only 62%. Almost identical values of sensitivity (92%) and specificity (61%) were attained by the closing pressure method only if the standard value limit was set a little higher, namely, at 0.35 kPa/l/s. FEV1, which is easiest to measure, was able to objectivate an airway obstruction in a manner comparable to that of Ros and Run; there was in fact even a closer statistical correlation between the body plethysmographic resistance mographic methods are suitable for screening examinations on account of their sensitivity. However, if the results on the examination are not in keeping with the overall clinical findings, further diagnostic clarification must be sought by performing a body plethysmographic measurement.