Airway occlusion assessed by single breath N2 test and lung P-V curve in healthy subjects and COPD patients

Matteo Pecchiari, Dejan Radovanovic, Pierachille Santus, Edgardo D'Angelo

Research output: Contribution to journalArticlepeer-review


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 languageEnglish
Pages (from-to)60-68
Number of pages9
JournalRespiratory Physiology and Neurobiology
Publication statusPublished - Dec 1 2016
Externally publishedYes


  • 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


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