title: Bedside estimation of recruitable alveolar collapse and hyperdistension by electrical impedance tomography.
abstract: OBJECTIVE
  To present a novel algorithm for estimating recruitable alveolar collapse and hyperdistension based on electrical impedance tomography (EIT) during a decremental positive end-expiratory pressure (PEEP) titration.
  
  
  METHODS
  Technical note with illustrative case reports.
  
  
  METHODS
  Respiratory intensive care unit.
  
  
  METHODS
  Patients with acute respiratory distress syndrome.
  
  
  METHODS
  Lung recruitment and PEEP titration maneuver.
  
  
  RESULTS
  Simultaneous acquisition of EIT and X-ray computerized tomography (CT) data. We found good agreement (in terms of amount and spatial location) between the collapse estimated by EIT and CT for all levels of PEEP. The optimal PEEP values detected by EIT for patients 1 and 2 (keeping lung collapse <10%) were 19 and 17 cmH(2)O, respectively. Although pointing to the same non-dependent lung regions, EIT estimates of hyperdistension represent the functional deterioration of lung units, instead of their anatomical changes, and could not be compared directly with static CT estimates for hyperinflation.
  
  
  CONCLUSIONS
  We described an EIT-based method for estimating recruitable alveolar collapse at the bedside, pointing out its regional distribution. Additionally, we proposed a measure of lung hyperdistension based on regional lung mechanics.
authors.affiliation: Respiratory Intensive Care Unit, University of São Paulo School of Medicine, São Paulo, Brazil.
authors.forename: Eduardo L V
authors.initials: EL
authors.lastname: Costa
authors.forename: João Batista
authors.initials: JB
authors.lastname: Borges
authors.forename: Alexandre
authors.initials: A
authors.lastname: Melo
authors.forename: Fernando
authors.initials: F
authors.lastname: Suarez-Sipmann
authors.forename: Carlos
authors.initials: C
authors.lastname: Toufen
authors.forename: Stephan H
authors.initials: SH
authors.lastname: Bohm
authors.forename: Marcelo B P
authors.initials: MB
authors.lastname: Amato
mesh_terms: D000328:Adult; D000465:Algorithms; D017097:Electric Impedance; D020342:Finite Element Analysis; D006801:Humans; D055370:Lung Injury / Q000209:etiology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D019095:Point-of-Care Systems; D011175:Positive-Pressure Respiration / Q000009:adverse effects* / Q000592:standards; D001261:Pulmonary Atelectasis / Q000209:etiology / Q000503:physiopathology; D011999:Recruitment, Neurophysiological / Q000502:physiology*; D012128:Respiratory Distress Syndrome / Q000628:therapy; D012131:Respiratory Insufficiency / Q000628:therapy