Airway closure and reopening assessed by the alveolar capsule oscillation technique

David R. Otis, Ferenc Petak, Zoltan Hantos, Jeffrey J. Fredberg, Roger D. Kamm

Research output: Contribution to journalArticle

38 Citations (Scopus)


An alveolar capsule oscillation technique was used to determine 1) the lobe pressure and volume at which airways close and reopen, 2) the effect of expiration rate on closing volume and pressure, 3) the phase in the breathing cycle at which airway closure occurs, and 4) the site of airway closure. Experiments were conducted in excised dog lobes; closure was detected by an abrupt increase in the input impedance of surface-mounted alveolar capsules. Mean transpulmonary pressure (Ptp) at closure was slightly less than zero (Ptp = -2.3 cmH2O); the corresponding mean reopening pressure was Ptp = 14 cmH2O. The expiration rate varied between i and 20% of total lobe capacity per second and had no consistent effect on the closing volume and pressure. When lung volume was cycled up to frequencies of 0.2 Hz, closure generally occurred on expiration rather than inspiration. These observations support the conclusion that mechanical collapse, rather than meniscus formation, is the most likely mechanism producing airway closure in normal excised dog lungs. Analysis of measured acoustic impedances and reopening pressures suggests that closure occurs in the most peripheral airways. Reopening during inspiration was often observed to consist of a series of stepwise decreases in capsule impedance, indicating a sequence of opening events.

Original languageEnglish
Pages (from-to)2077-2084
Number of pages8
JournalJournal of Applied Physiology
Issue number6
Publication statusPublished - Jun 1996


  • airway liquid lining
  • alveolar capsule technique
  • closing capacity
  • closing volume
  • residual volume

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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