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

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.

[1]  N. Krug,et al.  Dysfunction of pulmonary surfactant in asthmatics after segmental allergen challenge. , 1999, American Journal of Respiratory and Critical Care Medicine.

[2]  Albert-László Barabási,et al.  Avalanches and power-law behaviour in lung inflation , 1994, Nature.

[3]  T. Petty,et al.  Positive end-expiratory pressure. Physiology, indications, and contraindications. , 1973 .

[4]  J. Bates,et al.  Effects of cool, dry air stimulation on peripheral lung mechanics in asthma. , 2000, American journal of respiratory and critical care medicine.

[5]  D. Niewoehner,et al.  Human lung pressure-volume relationships: alveolar collapse and airway closure. , 1981, Journal of applied physiology: respiratory, environmental and exercise physiology.

[6]  J. Bates,et al.  Mechanical behaviour of the canine respiratory system at very low lung volumes. , 1994, Respiration physiology.

[7]  J. C. Smith,et al.  Surface forces in lungs. I. Alveolar surface tension-lung volume relationships. , 1986, Journal of applied physiology.

[8]  David W. Kaczka,et al.  Airway constriction pattern is a central component of asthma severity: the role of deep inspirations. , 2001, American journal of respiratory and critical care medicine.

[9]  B Jonson,et al.  Pressure-volume curves and compliance in acute lung injury: evidence of recruitment above the lower inflection point. , 1999, American journal of respiratory and critical care medicine.

[10]  J. Grotberg,et al.  Frequency dependence of pressure--volume loops in isolated dog lobes. , 1980, Journal of biomechanics.

[11]  D. Gaver,et al.  Effects of surface tension and viscosity on airway reopening. , 1990, Journal of applied physiology.

[12]  D. Tierney,et al.  Surface forces in the lung, atelectasis, and transpulmonary pressure. , 1966, Journal of applied physiology.

[13]  F. Plum.  Handbook of Physiology. , 1960 .

[14]  J. Mead,et al.  RELATION OF VOLUME HISTORY OF LUNGS TO RESPIRATORY MECHANICS IN ANESTHETIZED DOGS , 1959 .

[15]  J. Mead,et al.  Mechanical factors in distribution of pulmonary ventilation. , 1956, Journal of applied physiology.

[16]  R. Kamm,et al.  Role of pulmonary surfactant in airway closure: a computational study. , 1993, Journal of applied physiology.

[17]  J. Hildebrandt,et al.  Pressure-volume data of cat lung interpreted by a plastoelastic, linear viscoelastic model. , 1970, Journal of applied physiology.

[18]  J. Hildebrandt,et al.  Dynamic compliance, limit cycles, and static equilibria of excised cat lung. , 1971, Journal of applied physiology.

[19]  L. Mount.  The ventilation flow‐resistance and compliance of rat lungs , 1955, The Journal of physiology.

[20]  E. Roupie,et al.  Significance of the changes in the respiratory system pressure-volume curve during acute lung injury in rats. , 2001, American journal of respiratory and critical care medicine.

[21]  B Jonson,et al.  Influence of tidal volume on alveolar recruitment. Respective role of PEEP and a recruitment maneuver. , 2001, American journal of respiratory and critical care medicine.

[22]  B Suki,et al.  Airway inhomogeneities contribute to apparent lung tissue mechanics during constriction. , 1996, Journal of applied physiology.

[23]  R C Schroter,et al.  Bulk elastic properties of excised lungs and the effect of a transpulmonary pressure gradient. , 1973, Respiration physiology.

[24]  G. N. Franz,et al.  Trapped gas and lung hysteresis. , 1981, Respiration physiology.

[25]  J. Bates,et al.  Estimation of time-varying respiratory mechanical parameters by recursive least squares. , 1991, Journal of applied physiology.

[26]  G. N. Franz,et al.  Contribution of opening and closing of lung units to lung hysteresis. , 1995, Respiration physiology.

[27]  K. Hickling,et al.  Best compliance during a decremental, but not incremental, positive end-expiratory pressure trial is related to open-lung positive end-expiratory pressure: a mathematical model of acute respiratory distress syndrome lungs. , 2001, American journal of respiratory and critical care medicine.

[28]  H. E. Stanley,et al.  Life-support system benefits from noise , 1998, Nature.

[29]  J. Bates,et al.  Two-compartment modelling of respiratory system mechanics at low frequencies: gas redistribution or tissue rheology? , 1991, The European respiratory journal.

[30]  H. Frndova,et al.  The open lung during small tidal volume ventilation: concepts of recruitment and "optimal" positive end-expiratory pressure. , 1999, Critical care medicine.

[31]  G. N. Franz,et al.  Lung Area–Volume Models in Relation to the Recruitment–Derecruitment of Individual Lung Units , 2001, Annals of Biomedical Engineering.

[32]  S. Sorokin,et al.  The Respiratory System , 1983 .

[33]  J. Fredberg,et al.  Airway closure and reopening assessed by the alveolar capsule oscillation technique. , 1996, Journal of applied physiology.

[34]  H. Eugene Stanley,et al.  Mathematical Modeling of the First Inflation of Degassed Lungs , 1998, Annals of Biomedical Engineering.

[35]  P. Pelosi,et al.  Recruitment and derecruitment during acute respiratory failure: a clinical study. , 2001, American journal of respiratory and critical care medicine.

[36]  H. T. Moriya,et al.  Nonlinearity of respiratory mechanics during bronchoconstriction in mice with airway inflammation. , 2002, Journal of applied physiology.

[37]  R. Anafi,et al.  Mechanics of edematous lungs. , 2001, Journal of applied physiology.

[38]  J. Mead,et al.  Contribution of compliance of airways to frequency-dependent behavior of lungs. , 1969, Journal of applied physiology.

[39]  J. Bates,et al.  Respiratory mechanics in the normal dog determined by expiratory flow interruption. , 1989, Journal of applied physiology.

[40]  P. Pelosi,et al.  Recruitment and derecruitment during acute respiratory failure: an experimental study. , 2001, American journal of respiratory and critical care medicine.

[41]  Per Bak,et al.  How Nature Works , 1996 .

[42]  K. Hickling,et al.  The pressure-volume curve is greatly modified by recruitment. A mathematical model of ARDS lungs. , 1998, American journal of respiratory and critical care medicine.

[43]  David M. Raup,et al.  How Nature Works: The Science of Self-Organized Criticality , 1997 .

[44]  E SALAZAR,et al.  AN ANALYSIS OF PRESSURE-VOLUME CHARACTERISTICS OF THE LUNGS. , 1964, Journal of applied physiology.

[45]  D. Frazer,et al.  Trapped air in ventilated excised rat lungs. , 1976, Journal of applied physiology.

[46]  H E Stanley,et al.  Avalanche dynamics of crackle sound in the lung. , 2001, Physical review letters.