Time dependence of recruitment and derecruitment in the lung: a theoretical model

J Appl Physiol (1985). 2002 Aug;93(2):705-13. doi: 10.1152/japplphysiol.01274.2001.


Recruitment and derecruitment (R/D) of air spaces within the lung is greatly enhanced in lung injury and is thought to be responsible for exacerbating injury during mechanical ventilation. There is evidence to suggest that R/D is a time-dependent phenomenon. We have developed a computer model of the lung consisting of a parallel arrangement of airways and alveolar units. Each airway has a critical pressure (Pcrit) above which it tends to open and below which it tends to close but at a rate determined by how far pressure is from Pcrit. With an appropriate distribution of Pcrit and R/D velocity characteristics, the model able to produce realistic first and second pressure-volume curves of a lung inflated from an initially degassed state. The model also predicts that lung elastance will increase transiently after a deep inflation to a degree that increases as lung volume decreases and as the lung becomes injured. We conclude that our model captures the time-dependent mechanical behavior of the lung due to gradual R/D of lung units.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Elasticity
  • Humans
  • Lung / physiology*
  • Lung Injury
  • Lung Volume Measurements
  • Models, Biological*
  • Pressure
  • Pulmonary Atelectasis / physiopathology
  • Respiration, Artificial / adverse effects
  • Time Factors