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Updated: May 15, 2026

Combining Volumetric Capnography And Barometric Plethysmography To Measure The Lung Structure-function Relationship
Published on: January 8, 2019
Volume rather than flow incentive spirometry is effective in improving chest wall expansion and abdominal
Denise de Moraes Paisani1, Adriana Claudia Lunardi, Cibele Cristine Berto Marques da Silva
1Department of Physical Therapy, School of Medicine, University of São Paulo, São Paulo, Brazil.
Background:
Incentive spirometers are widely used in clinical practice and classified as flow-oriented (FIS) and volume-oriented (VIS). Until recently the respiratory inductive plethysmography used to evaluate the effects of incentive spirometry on chest wall mechanics presented limitations, which may explain why the impact of VIS and FIS remains poorly known.
Objective:
To compare the effects of VIS and FIS on thoracoabdominal mechanics and respiratory muscle activity in healthy volunteers.
Methods:
This cross-sectional trial assessed 20 subjects (12 female, ages 20-40 years, body mass index 20-30 kg/m(2)). All subjects performed 8 quiet breaths and 8 deep breaths with FIS and VIS, in a randomized order. We measured thoracoabdominal chest wall, upper and lower rib-cage, and abdominal volumes with optoelectronic plethysmography, and the muscle activity of the sternocleidomastoid and superior and inferior intercostal muscles with electromyography.
Results:
VIS increased chest wall volume more than did FIS (P = .007) and induced a larger increase in the upper and lower rib-cages and abdomen (156%, 91%, and 151%, respectively, P < .001). By contrast, FIS induced more activity in the accessory muscles of respiration than did VIS (P < .001).
Conclusions:
VIS promotes a greater increase in chest wall volume, with a larger abdominal contribution and lower respiratory muscle activity, than does FIS in healthy adults.
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