Frequency and causes of combined obstruction and restriction identified in pulmonary function tests in adults
Diaz-Guzman, E.; McCarthy, K.; Siu, A.; Stoller, J.K.
Respiratory Care 55(3): 310-316
2010
ISSN/ISBN: 0020-1324 PMID: 20196880 Document Number: 639754
The frequency of combined obstruction and restriction identified in pulmonary function tests has not been well described. Moreover, although the causes of combined-obstruction-and-restriction patterns are known, the frequency of the various etiologies has received little attention. We retrospectively reviewed medical records and surveyed pulmonologists. 43,212 PFT sessions were evaluated, which yielded 130 patients who satisfied our criteria for spirometry evidence of combined obstruction and restriction. Their demographic features were: mean +/- SD age 54 +/- 14 y, 51% male, mean +/- SD body mass index 28.8 +/- 6.7 kg/m(2), mean +/- SD height 174 +/- 9 cm (men) and 162 +/- 7 cm (women). The causes of combined obstruction and restriction were classified as either a pulmonary parenchymal disorder (Group A, n = 49, 38%) or a combination of pulmonary parenchymal and non-pulmonary diseases (Group B, n = 63, 48%). In 18 patients (14%) no clear etiology of combined obstruction and restriction could be determined. The most common pulmonary disease was chronic obstructive pulmonary disease (45/130, 35%), and the most common non-parenchymal disease was congestive heart failure (27/130, 21%). We electronically sent a survey to 55 pulmonary physicians, of whom 30 (55%) responded. The respondents estimated that combined obstruction and restriction occurs in approximately 20% of all the pulmonary function tests performed in their practices and that pulmonary parenchymal diseases were responsible for 35% of all instances of combined obstruction and restriction. Combined obstruction and restriction occurs infrequently and is more commonly caused by a combination of pulmonary parenchymal and non-pulmonary disorders. Pulmonologists' impressions regarding the frequency and causes are generally discordant with the observed frequencies.