Density-dependent reduction of nitric oxide diffusing capacity after pneumonectomy

Connie C W Hsia, Xiao Yan, D. Merrill Dane, Robert L. Johnson

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Airway lengthening after pneumonectomy (PNX) may increase diffusive resistance to gas mixing (1/DG); the effect is accentuated by increasing acinar gas density but is difficult to detect from lung CO-diffusing capacity (DLCO). Because lung NO-diffusing capacity (DLNO) is three- to fivefold that of DLCO, whereas 1/DG for NO and CO are similar, we hypothesized that a density-dependent fractional reduction would be greater for DLNO than for DLCO. We measured DLNO and DLCO at two tidal volumes (VT) and with three background gases [helium (He), nitrogen (N2), and sulfur hexafluoride (SF6)] in immature dogs 3 and 9 mo after right PNX (5 and 11 mo of age). At maturity (11 mo), background gas density had no effect on DLNO, DLCO, or DLNO-to-DLCO ratio in sham controls. In PNX animals, DLNO declined 25-50% in SF6 relative to He and N2, and DLNO/DLCO declined ∼50% in SF6 relative to He at a VT of 15 ml/kg, consistent with a significant 1/DG. At 5 mo of age, DLNO/DLCO declined 25-45% in SF6 relative to He and N2 in both groups, but DLCO increased paradoxically in SF6 relative to N2 or He by 20-60%. Findings suggest that SF6, besides increasing 1/DG, may redistribute ventilation and/or enhance acinar penetration of the convective front.

Original languageEnglish (US)
Pages (from-to)1926-1932
Number of pages7
JournalJournal of applied physiology
Issue number5
StatePublished - May 1 2003


  • Carbon monoxide
  • Dog
  • Helium
  • Lung diffusing capacity
  • Sulfur hexafluoride

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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