title: Early patterns of static pressure-volume loops in ARDS and their relations with PEEP-induced recruitment.
abstract: OBJECTIVE
  Evaluation of low-flow pressure-volume loop at the bedside in ARDS, as an aid to assess recruitment produced by PEEP.
  
  
  METHODS
  Low-flow pressure-volume loop at the bedside were obtained on the first day of respiratory support in 54 successive pulmonary ARDS patients (49 of whom had pneumonia) treated between April 1999 and June 2002. From the loop obtained at ZEEP, we determined manually the lower inflexion point (LIP). By superimposing the pressure-volume loop at ZEEP and at PEEP, we evaluated recruitment obtained at a constant elastic pressure of 20 cm H2O.
  
  
  RESULTS
  We observed two different types of loops, according to the pattern of the inflation limb. In type 1 (38 cases) the inflation limb was characterized by an inflexion zone, resulting from a progressive or a sudden improvement in compliance. In type 2 (16 patients) the inflation limb was virtually linear, without significant improvement in compliance during inflation, which remained particularly low (26+/-9 cm H2O). Use of a low PEEP (6+/-2 cm H2O) produced a substantial recruitment in type-1 patients (74+/-53 ml), which was marginally improved by a higher PEEP (89+/-54 ml). In type 2, recruitment produced by PEEP was significantly lower (48+/-26 ml, p=0.006).
  
  
  CONCLUSIONS
  Pressure-volume loop at bedside confirmed that a low PEEP was sufficient to obtain recruitment in ARDS. This study also individualized a group of pulmonary ARDS patients exhibiting a markedly reduced compliance, in whom recruitment obtained by PEEP was limited.
authors.affiliation: Medical Intensive Care Unit, University Hospital Ambroise Paré, Assistance Publique Hôpitaux de Paris, 9 avenue Charles de Gaulle, 92104, Boulogne Cedex, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Vieillard-Baron
authors.forename: Sebastien
authors.initials: S
authors.lastname: Prin
authors.forename: Karim
authors.initials: K
authors.lastname: Chergui
authors.forename: Bernard
authors.initials: B
authors.lastname: Page
authors.forename: Alain
authors.initials: A
authors.lastname: Beauchet
authors.forename: François
authors.initials: F
authors.lastname: Jardin
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D016009:Chi-Square Distribution; D003422:Critical Care / Q000379:methods; D005260:Female; D005652:Functional Residual Capacity; D006801:Humans; D008170:Lung Compliance; D008176:Lung Volume Measurements; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D019095:Point-of-Care Systems; D011175:Positive-Pressure Respiration / Q000379:methods*; D011446:Prospective Studies; D011659:Pulmonary Gas Exchange; D012128:Respiratory Distress Syndrome / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy*; D015656:Respiratory Mechanics; D012720:Severity of Illness Index; D013147:Spirometry; D013990:Tidal Volume; D013997:Time Factors; D016896:Treatment Outcome