Effect of lung volume and intrathoracic pressure on airway mucosal blood flow in man

A. Breitenbücher, A. D. Chediak, A. Wanner

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


We have recently described an inert soluble gas uptake technique (using dimethyl-ether, DME) for the non-invasive measurement of airway mucosal blood flow Q̇aw, in humans. In the present study, we assessed the effects of lung volume and intrathoracic pressure on Q̇aw, in healthy non-smokers (age range 19-52 years). Q̇aw was calculated from the steady-uptake of DME from a 50 ml segment of the antomic dead space. The mean (± SD) Q̇aw of three consecutive measurement at a lung volume of FRC + 300 ml was 8.3 ± 2.3, 8.6±2.6 and 8.3 ± 2.7 ml · min-1 (n = 13; coefficient of variation 14 ± 7%). At zero airway pressure, there was an inverse relationship between apparent Q̇aw on the one hand and lung volume and anatomic dead space (DS) on the other: mean Q̇aw was 12.2 ± 5.3, 8.2 ± 2.5 and 5.3 ± 2.2. ml · min-1 at RV + 300 ml(DS = 131 ± 11 ml), FRC + 300 ml (DS = 153 ± 12 ml) and TCL (DS = 206 ± 22 ml) positions, respectively (n = 11; P < 0.05 among all three). At a lung volume of FRC + 300 ml, an increase in intrathoracic pressure to +25 cmH2O (modified Valsalva maneuver) decreased mean Q̇aw to 3.3 ± 2.8 ml · min-1 while a decrease in intrathoracic pressure to -35 cmH2O (modified Müller maneuver) increased mean Q̇aw to 17.1 ± 7.4ml · min-1 from a control value of 7.2 ± 2.2 ml · min · min- (n = 7; P < 0.05 among all three). These results indicate that lung volume has an effect on apparent Q̇aw, presumably by influencing the depth to which the analyzed anatomical dead space segment extends into the bronchial tree. The results alos show that changes in intrathoracic pressure alter Q̇aw possibly reflecting concomitant changes in left ventricular output and its distribution to intrathoracic and extrathoracic vascular beds.

Original languageEnglish (US)
Pages (from-to)249-258
Number of pages10
JournalRespiration Physiology
Issue number2-3
StatePublished - May 1994


  • Airways, blood flow, lung volume, intrathoracic pressure
  • Blood flow, airways, soluble inert gases
  • Inert gases, soluble, airways blood flow
  • Mammals, humans
  • Pressure, intrathoracic
  • Volume lung

ASJC Scopus subject areas

  • Physiology
  • Pulmonary and Respiratory Medicine


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