Abstract
Purpose To determine whether the analysis of the slow expiratory transpulmonary pressure–volume (PL-V) curve provides an alternative to the single-breath nitrogen test (SBN) for the assessment of the closing volume (CV). Methods SBN test and slow deflation PL-V curve were simultaneously recorded in 40 healthy subjects and 43 COPD patients. Onset of phase IV identified CV in SBN test (CVSBN), whereas in the PL-V curve CV was identified by: a) deviation from the exponential fit (CVexp), and b) inflection point of the interpolating sigmoid function (CVsig). Results In the absence of phase IV, COPD patients exhibited a clearly discernible inflection in the PL-V curve. In the presence of phase IV, CVSBN and CVexp coincided (CVSBN/CVexp = 1.04 ± 0.04 SD), whereas CVsig was systematically larger (CVsig/CVexp = 2.1 ± 0.86). Conclusion The coincidence between CVSBN and CVexp, and the presence of the inflection in the absence of phase IV indicate that the deviation of the PL-V curve from the exponential fit reliably assesses CV.
Original language | English |
---|---|
Pages (from-to) | 60-68 |
Number of pages | 9 |
Journal | Respiratory Physiology and Neurobiology |
Volume | 234 |
DOIs | |
Publication status | Published - Dec 1 2016 |
Externally published | Yes |
Keywords
- Airway resistance
- Closing volume
- Lung pressure-volume curve
- Phase IV
- Single breath nitrogen test
- Single breath oxygen test
ASJC Scopus subject areas
- Neuroscience(all)
- Physiology
- Pulmonary and Respiratory Medicine