title: Maximum static inspiratory and expiratory pressures with different lung volumes.
abstract: BACKGROUND
  Maximum pressures developed by the respiratory muscles can indicate the health of the respiratory system, help to determine maximum respiratory flow rates, and contribute to respiratory power development. Past measurements of maximum pressures have been found to be inadequate for inclusion in some exercise models involving respiration.
  
  
  METHODS
  Maximum inspiratory and expiratory airway pressures were measured over a range of lung volumes in 29 female and 19 male adults. A commercial bell spirometry system was programmed to occlude airflow at nine target lung volumes ranging from 10% to 90% of vital capacity.
  
  
  RESULTS
  In women, maximum expiratory pressure increased with volume from 39 to 61 cmH2O and maximum inspiratory pressure decreased with volume from 66 to 28 cmH2O. In men, maximum expiratory pressure increased with volume from 63 to 97 cmH2O and maximum inspiratory pressure decreased with volume from 97 to 39 cmH2O. Equations describing pressures for both sexes are: Pe/Pmax = 0.1426 Ln( %VC) + 0.3402 R2 = 0.95 Pi/Pmax = 0.234 Ln(100 - %VC) - 0.0828 R2 = 0.96
  
  
  CONCLUSIONS
  These results were found to be consistent with values and trends obtained by other authors. Regression equations may be suitable for respiratory mechanics models.
authors: The Institute for Systems Biology, 1441 North 34th Street, Seattle, WA 98103, USA. clausted@systemsbiology.org
authors: Christopher G
authors: CG
authors: Lausted
authors: Arthur T
authors: AT
authors: Johnson
authors: William H
authors: WH
authors: Scott
authors: Monique M
authors: MM
authors: Johnson
authors: Karen M
authors: KM
authors: Coyne
authors: Derya C
authors: DC
authors: Coursey