title: End-Expiratory Volume and Oxygenation: Targeting PEEP in ARDS Patients.
abstract: BACKGROUND
  Changes in end-expiratory lung volume (∆EELV) in response to changes in PEEP (∆PEEP) have not been reported in mechanically ventilated patients with ARDS. The purpose of this study was to determine the utility of measurements of ∆EELV in determining optimal PEEP in ARDS patients.
  
  
  METHODS
  Nine patients with ARDS were prospectively recruited. ∆EELV was measured using magnetometers during serial decremental PEEP trials. Changes in PaO2 (∆PaO2) were simultaneously measured. Static respiratory system compliance (CRS), ∆PaO2/∆PEEP, and ∆EELV/∆PEEP were calculated at each level of PEEP.
  
  
  RESULTS
  For the group, ∆EELV decreased by 1.09 ± 0.13 L (mean ± SD) as PEEP was reduced from 20 to 0 cm H2O with the greatest changes in ∆EELV occurring over the mid range of the decremental PEEP curve. Optimal values for CRS, ∆EELV/∆PEEP, and ∆PaO2/∆PEEP could be identified for each patient and occurred at PEEP levels ranging from 10 to 17.5 cm H2O. There was a significant correlation (r = 0.712, p = 0.047) between ∆PaO2/∆PEEP and ∆EELV/∆PEEP.
  
  
  CONCLUSIONS
  ∆EELV can be measured from a decremental PEEP curve. Since ∆EELV is highly correlated with ∆PaO2, measures of ∆PaO2/∆PEEP may provide a surrogate for measures of ∆EELV/∆PEEP. Combining measures of ∆EELV/∆PEEP with measures of CRS may provide a novel means of determining optimal PEEP in patients with ARDS.
authors.affiliation: Pulmonary, Critical Care, and Sleep Medicine, Mid-Western Regional Hospital, Dooradoyle, Limerick, Ireland. brian_casserly@brown.edu.|University Hospital Limerick, Dooradoyle, Limerick, Ireland. brian_casserly@brown.edu.
authors.forename: Brian
authors.initials: B
authors.lastname: Casserly
authors.affiliation: Division of Pulmonary, Critical Care and Sleep Medicine, The Memorial Hospital of Rhode Island, 111 Brewster Street, Pawtucket, RI, USA.
authors.forename: F Dennis
authors.initials: FD
authors.lastname: McCool
authors.affiliation: Director of Statistical Consulting Unit, University of Limerick, Limerick, Ireland.
authors.forename: Jean
authors.initials: J
authors.lastname: Saunders
authors.affiliation: University of Limerick, Limerick, Ireland.
authors.forename: Narendran
authors.initials: N
authors.lastname: Selvakumar
authors.affiliation: Division of Pulmonary, Critical Care and Sleep Medicine, Rhode Island Hospital, 593 Eddy Street, Providence, RI, USA.
authors.forename: Mitchell M
authors.initials: MM
authors.lastname: Levy
mesh_terms: D005260:Female; D005652:Functional Residual Capacity; D006801:Humans; D008168:Lung / Q000503:physiopathology; D008170:Lung Compliance; D008176:Lung Volume Measurements; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D010313:Partial Pressure; D011175:Positive-Pressure Respiration / Q000379:methods; D011446:Prospective Studies; D012128:Respiratory Distress Syndrome / Q000503:physiopathology* / Q000628:therapy*
chemical_list: D010100:Oxygen
keywords: Acute respiratory distress syndrome; Compliance; Lung volume