title: Quantifying unintended exposure to high tidal volumes from breath stacking dyssynchrony in ARDS: the BREATHE criteria.
abstract: OBJECTIVE
  Breath stacking dyssynchrony generates higher tidal volumes than intended, potentially increasing lung injury risk in acute respiratory distress syndrome (ARDS). Lack of validated criteria to quantify breath stacking dyssynchrony contributes to its under-recognition. This study evaluates performance of novel, objective criteria for quantifying breath stacking dyssynchrony (BREATHE criteria) compared to existing definitions and tests if neuromuscular blockade eliminates high-volume breath stacking dyssynchrony in ARDS.
  
  
  METHODS
  Airway flow and pressure were recorded continuously for up to 72 h in 33 patients with ARDS receiving volume-preset assist-control ventilation. The flow-time waveform was integrated to calculate tidal volume breath-by-breath. The BREATHE criteria considered five domains in evaluating for breath stacking dyssynchrony: ventilator cycling, interval expiratory volume, cumulative inspiratory volume, expiratory time, and inspiratory time.
  
  
  RESULTS
  The observed tidal volume of BREATHE stacked breaths was 11.3 (9.7-13.3) mL/kg predicted body weight, significantly higher than the preset volume [6.3 (6.0-6.8) mL/kg; p < 0.001]. BREATHE identified more high-volume breaths (≥2 mL/kg above intended volume) than the other existing objective criteria for breath stacking [27 (7-59) vs 19 (5-46) breaths/h; p < 0.001]. Agreement between BREATHE and visual waveform inspection was high (raw agreement 96.4-98.1 %; phi 0.80-0.92). Breath stacking dyssynchrony was near-completely eliminated during neuromuscular blockade [0 (0-1) breaths/h; p < 0.001].
  
  
  CONCLUSIONS
  The BREATHE criteria provide an objective definition of breath stacking dyssynchrony emphasizing occult exposure to high tidal volumes. BREATHE identified high-volume breaths missed by other methods for quantifying this dyssynchrony. Neuromuscular blockade prevented breath stacking dyssynchrony, assuring provision of the intended lung-protective strategy.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, University of California, San Diego, 200 West Arbor Drive, #8409, San Diego, CA, 92103, USA. jbeitler@ucsd.edu.
authors.forename: Jeremy R
authors.initials: JR
authors.lastname: Beitler
authors.affiliation: Division of Sleep and Circadian Disorders, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.|Department of Allergy, Immunology, and Respiratory Medicine and Central Clinical School, The Alfred and Monash University, Melbourne, Australia.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Sands
authors.affiliation: Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Boston, MA, USA.
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Loring
authors.affiliation: Division of Pulmonary and Critical Care Medicine, University of California, San Diego, 200 West Arbor Drive, #8409, San Diego, CA, 92103, USA.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Owens
authors.affiliation: Division of Pulmonary and Critical Care Medicine, University of California, San Diego, 200 West Arbor Drive, #8409, San Diego, CA, 92103, USA.
authors.forename: Atul
authors.initials: A
authors.lastname: Malhotra
authors.affiliation: Division of Pulmonary and Critical Care Medicine, University of California, San Diego, 200 West Arbor Drive, #8409, San Diego, CA, 92103, USA.
authors.forename: Roger G
authors.initials: RG
authors.lastname: Spragg
authors.affiliation: Departments of Medicine and Anesthesia, and the Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, USA.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Matthay
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital, Boston, MA, USA.
authors.forename: B Taylor
authors.initials: BT
authors.lastname: Thompson
authors.affiliation: Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Boston, MA, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Talmor
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D001239:Inhalation / Q000502:physiology; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012121:Respiration, Artificial / Q000009:adverse effects*; D012128:Respiratory Distress Syndrome / Q000503:physiopathology / Q000628:therapy*; D012129:Respiratory Function Tests / Q000379:methods*; D056152:Respiratory Rate / Q000502:physiology; D013990:Tidal Volume / Q000502:physiology*; D055397:Ventilator-Induced Lung Injury / Q000517:prevention & control*; D012122:Ventilators, Mechanical
keywords: Acute lung injury; Acute respiratory distress syndrome; Mechanical ventilation; Patient–ventilator dyssynchrony; Respiratory mechanics; Ventilator-induced lung injury