Potential for lung recruitment estimated by the recruitment-to-inflation ratio in acute respiratory distress syndrome a clinical trial

Lu Chen, Lorenzo Del Sorbo, Domenico L. Grieco, Detajin Junhasavasdikul, Nuttapol Rittayamai, Ibrahim Soliman, Michael C. Sklar, Michela Rauseo, Niall D. Ferguson, Eddy Fan, Jean Christophe M. Richard, Laurent Brochard

Research output: Contribution to journalArticlepeer-review


Rationale: Response to positive end-expiratory pressure (PEEP) in acute respiratory distress syndrome depends on recruitability. We propose a bedside approach to estimate recruitability accounting for the presence of complete airway closure. Objectives: To validate a single-breath method for measuring recruited volume and test whether it differentiates patients with different responses to PEEP. Methods: Patients with acute respiratory distress syndrome were ventilated at 15 and 5 cm H2O of PEEP. Multiple pressure–volume curves were compared with a single-breath technique. Abruptly releasing PEEP (from 15 to 5 cm H2O) increases expired volume: the difference between this volume and the volume predicted by compliance at low PEEP (or above airway opening pressure) estimated the recruited volume by PEEP. This recruited volume divided by the effective pressure change gave the compliance of the recruited lung; the ratio of this compliance to the compliance at low PEEP gave the recruitment-to-inflation ratio. Response to PEEP was compared between high and low recruiters based on this ratio. Measurements and Main Results: Forty-five patients were enrolled. Four patients had airway closure higher than high PEEP, and thus recruitment could not be assessed. In others, recruited volume measured by the experimental and the reference methods were strongly correlated (R2 = 0.798; P, 0.0001) with small bias (221 ml). The recruitment-to-inflation ratio (median, 0.5; range, 0–2.0) correlated with both oxygenation at low PEEP and the oxygenation response; at PEEP 15, high recruiters had better oxygenation (P = 0.004), whereas low recruiters experienced lower systolic arterial pressure (P = 0.008). Conclusions: A single-breath method quantifies recruited volume. The recruitment-to-inflation ratio might help to characterize lung recruitability at the bedside.

Original languageEnglish
Pages (from-to)178-187
Number of pages10
JournalAmerican Journal of Respiratory and Critical Care Medicine
Issue number2
Publication statusPublished - Jan 15 2020
Externally publishedYes


  • Acute respiratory distress syndrome
  • Artificial respiration
  • Mechanical ventilators
  • Positive-pressure respiration
  • Respiratory mechanics

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine
  • Critical Care and Intensive Care Medicine


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