Effects of positive expiratory pressure on pulmonary clearance of aerosolized technetium-99m-labeled diethylenetriaminepentaacetic acid in healthy individuals

OBJECTIVE: To evaluate the effects of positive expiratory pressure (PEP) on pulmonary epithelial membrane permeability in healthy subjects. METHODS: We evaluated a cohort of 30 healthy subjects (15 males and 15 females) with a mean age of 28.3 ± 5.4 years, a mean FEV(1)/FVC ratio of 0.89 ± 0.14, and a mean FEV(1) of 98.5 ± 13.1% of predicted. Subjects underwent technetium-99m-labeled diethylenetriaminepentaacetic acid ((99m)Tc-DTPA) radioaerosol inhalation lung scintigraphy in two stages: during spontaneous breathing; and while breathing through a PEP mask at one of three PEP levels-10 cmH(2)O (n = 10), 15 cmH(2)O (n = 10), and 20 cmH(2)O (n = 10). The (99m)Tc-DTPA was nebulized for 3 min, and its clearance was recorded by scintigraphy over a 30-min period during spontaneous breathing and over a 30-min period during breathing through a PEP mask. RESULTS: The pulmonary clearance of (99m)Tc-DTPA was significantly shorter when PEP was applied-at 10 cmH(2)O (p = 0.044), 15 cmH(2)O (p = 0.044), and 20 cmH(2)O (p = 0.004)-in comparison with that observed during spontaneous breathing. CONCLUSIONS: Our findings indicate that PEP, at the levels tested, is able to induce an increase in pulmonary epithelial membrane permeability and lung volume in healthy subjects.