Complete reference values and prediction equations for pulmonary function tests in Omani adults: a) Reference values for lung volumes b) Single-breath carbon monoxide diffusing capacity prediction equations

The interpretation and categorization of lung function values depend on comparison with reference values derived from "normal" populations. Hence, the accuracy of the reference values has important implications as the measured values are always compared to the established standards to know whether they are normal or low. Most pulmonary function laboratories use reference values derived from western populations. However, because of the ethnic differences in normal pulmonary function values the prediction equations based on western populations may not be accurate for others. The lung function can be assessed physiologically in many ways and the classical pulmonary function tests include Spirometry, Lung volumes and Diffusion. We have computed reference values for spirometry variables for Omani population and were published as two articles, one for the adults and the other for children. To complete this process of standardization of lung function we need to develop new equations for the rest of the lung function variables; Lung volumes and diffusion. We plan to derive reference equations and values for the lung volumes; Residual Volume, Functional Residual Capacity and Total Lung Capacity as well as the appropriate values and equations for carbon monoxide diffusion and diffusion coefficient. Around 500 normal subjects will be invited to undergo full lung function studies with the existing facilities in the pulmonary function laboratory of the Clinical Physiology department, SQUH. Once the measurements are made on all subjects, linear regression equations for each of the lung function parameters based on age, height and weight will be computed. Correlation coefficient among the lung function parameters for age, height and weight for each sex will also be derived separately.