title: Effect of breathing helium-oxygen on static lung volumes and lung recoil in normal man.
abstract: Static lung volumes and static elastic recoil pressure (Pel) were measured in normal subjects breathing air and 80% helium plus 20% oxygen (He+O2). In 22 subjects, He+O2 produced small but significant increases in total lung capacity (TLC) (mean 0.11 liter, P less than 0.001) and residual volume (mean 0.10 liter, P less than 0.01) without change in vital capacity or functional residual capacity. The mechanisms for this change are obscure. In 10 subjects, breathing He+O2 had no significant effect on Pel (paired t-test) at any lung volume measured (50-80% TLC). In one subject, Pel at 70 and 80% TLC was significantly higher on air than on He+O2 (unpaired t-test, P less than 0.05). Because changes in lung volumes and lung recoil were small, we concluded that these effects do not negate the clinical utility of He+O2 flow-volume curves.
mesh_terms: D000328:Adult; D005260:Female; D006371:Helium / Q000494:pharmacology*; D006801:Humans; D008168:Lung / Q000187:drug effects*; D008170:Lung Compliance / Q000187:drug effects; D008176:Lung Volume Measurements; D008297:Male; D008449:Maximal Expiratory Flow-Volume Curves; D010100:Oxygen / Q000494:pharmacology*; D011312:Pressure; D012115:Residual Volume; D014109:Total Lung Capacity
chemical_list: D006371:Helium; D010100:Oxygen