Spirometry in selected clinical situations

Abstract

Spirometry is the most frequently performed functional test of the respiratory system. In pulmonological practice it is a basic tool used to diagnose ventilation disorders and to monitor treatment. The results obtained during the test are compared to predicted values, that is, assumed parameter values, computed on the basis of anthropometrical data such as: age, gender and height, with the use of complex equations.  The use of additional variables including, e.g. an ethnic group or a race as well as corrective factors, enables a more exact determination of their values. Spirometry can be conducted in a sitting or standing position; however, for the subject safety reasons it is usually performed in a sitting position. It allows to eliminate the risk of fall as a result of syncope or impaired balance. Spirometry in a standing position should be considered in measurably obese patients or in patients with a wide abdominal circumference caused by other reasons. Patients with normal body weight obtain equivalent or slightly higher spirometric values in a standing position. In the selected clinical situations some problems with the measurement of the actual hight of patients in a standard way (measurement without shoes, feet together, upright position, eyes straight ahead) and with correct calculation of predicted values occur. They are, among others, silhouette-disturbing disorders or diseases causing changes in body proportions, from the less often occurring, like Marfan syndrome or achondroplasia, to more frequent posture defects and mobility impairments. These diseases influence the change of the predictive functional parameter values which are used to compare with the obtained results. The aim of the study is to demonstrate the methods of height and predicted values determination on the basis of measurements of ranges between different body points with the use of simple and complex equations in a group of patients in whom the application of standard measurement methods is impossible.