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The Influence of Different Mouthpieces on Impulse Oscillometry Results
Gustavo Henrique Dionísio1, Daniele Oliveira Dos Santos1, Larissa Perossi1
1Department of Biomechanics, Medicine, and Rehabilitation of the Locomotor System, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil.
Background:
Impulse oscillometry is a method of airway assessment and diagnosis that provides data on lung mechanics. In the literature, studies have used different types of mouthpieces or did not describe the model used for the tests. We sought to compare the 3 most commonly described mouthpieces in terms of test results, comfort, and subject preference.
Methods:
Thirty-nine healthy volunteers were evaluated with spirometry and impulse oscillometry, assessing the resistance at 5 Hz and 20 Hz (R5 and R20, respectively), reactance at 5 Hz (X5), reactance area, and resonant frequency. A filter heat exchanger with a circular mouthpiece (B1), a filter heat exchanger with an oval mouthpiece (B2), and a filter heat exchanger with a circular mouthpiece coupled with a free-flow piece (B3) were compared using an acceptability and tolerance scale, and subjects noted their preference.
Results:
Statistical analysis showed differences between all the mouthpieces and the predicted values for R5, R20, and X5. The mouthpiece comparison showed differences in R5 between a filter heat exchanger with an oval mouthpiece (B2) and a circular mouthpiece coupled with a free-flow piece (B3) (P = .007); resonant frequency between a filter heat exchanger with a circular mouthpiece (B1) and a filter heat exchanger with an oval mouthpiece (B2) (P = .004) and between a filter heat exchanger with a circular mouthpiece (B1) and a circular mouthpiece coupled with a free-flow piece (B3) (P = .003); and reactance area between a filter heat exchanger with a circular mouthpiece (B1) and a circular mouthpiece coupled with a free-flow piece (B3) (P = .01). In the subjective evaluation, acceptability and tolerance differences were found in the ease of carrying out the evaluation, and no difference was found with regard to the degree of discomfort. Ten subjects preferred a filter heat exchanger with a circular mouthpiece (B1), 15 preferred a filter heat exchanger with an oval mouthpiece (B2), and 14 preferred a circular mouthpiece coupled with a free-flow piece (B3).
Conclusions:
A circular mouthpiece coupled with a free-flow piece (B3) appeared to be the most suitable mouthpiece for the impulse oscillometry tests. It assured smaller impedance values for the respiratory system, and subjects expressed the most confidence in using this mouthpiece.
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