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

ABSTRACT

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 FEV₁/FVC ratio of 0.89 ± 0.14, and a mean FEV₁ of 98.5 ± 13.1% of predicted. Subjects underwent technetium-99m-labeled diethylenetriaminepentaacetic acid ^(99mTc-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 cmH₂O (n = 10), 15 cmH₂O (n = 10), and 20 cmH₂O (n = 10). The ^99mTc-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 ^99mTc-DTPA was significantly shorter when PEP was applied-at 10 cmH₂O (p = 0.044), 15 cmH₂O (p = 0.044), and 20 cmH₂O (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.

Keywords:
Lung/metabolism; Technetium Tc 99m pentetate/pharmacokinetics; Radiopharmaceuticals; Positive-pressure respiration