title: The effect of high-frequency oscillatory ventilation combined with tracheal gas insufflation on extravascular lung water in patients with acute respiratory distress syndrome: a randomized, crossover, physiologic study.
abstract: OBJECTIVE
  High-frequency oscillation combined with tracheal gas insufflation (HFO-TGI) improves oxygenation in patients with acute respiratory distress syndrome (ARDS). There are limited physiologic data regarding the effects of HFO-TGI on hemodynamics and pulmonary edema during ARDS. The aim of this study was to investigate the effect of HFO-TGI on extravascular lung water (EVLW).
  
  
  METHODS
  We conducted a prospective, randomized, crossover study. Consecutive eligible patients with ARDS received sessions of conventional mechanical ventilation with recruitment maneuvers (RMs), followed by HFO-TGI with RMs, or vice versa. Each ventilatory technique was administered for 8 hours. The order of administration was randomly assigned. Arterial/central venous blood gas analysis and measurement of hemodynamic parameters and EVLW were performed at baseline and after each 8-hour period using the single-indicator thermodilution technique.
  
  
  RESULTS
  Twelve patients received 32 sessions. Pao2/fraction of inspired oxygen and respiratory system compliance were higher (P<.001 for both), whereas extravascular lung water index to predicted body weight and oxygenation index were lower (P=.021 and .029, respectively) in HFO-TGI compared with conventional mechanical ventilation. There was a significant correlation between Pao2/fraction of inspired oxygen improvement and extravascular lung water index drop during HFO-TGI (Rs=-0.452, P=.009).
  
  
  CONCLUSIONS
  High-frequency oscillation combined with tracheal gas insufflation improves gas exchange and lung mechanics in ARDS and potentially attenuates EVLW accumulation.
authors.affiliation: First Department of Critical Care Medicine and Pulmonary Services, National and Kapodistrian University of Athens Medical School, Evaggelismos General Hospital, Athens, Greece. Electronic address: vrettou@hotmail.com.
authors.forename: Charikleia S
authors.initials: CS
authors.lastname: Vrettou
authors.affiliation: First Department of Critical Care Medicine and Pulmonary Services, National and Kapodistrian University of Athens Medical School, Evaggelismos General Hospital, Athens, Greece.
authors.forename: Spyros G
authors.initials: SG
authors.lastname: Zakynthinos
authors.affiliation: First Department of Critical Care Medicine and Pulmonary Services, National and Kapodistrian University of Athens Medical School, Evaggelismos General Hospital, Athens, Greece.
authors.forename: Sotirios
authors.initials: S
authors.lastname: Malachias
authors.affiliation: First Department of Critical Care Medicine and Pulmonary Services, National and Kapodistrian University of Athens Medical School, Evaggelismos General Hospital, Athens, Greece.
authors.forename: Spyros D
authors.initials: SD
authors.lastname: Mentzelopoulos
mesh_terms: D000328:Adult; D001784:Blood Gas Analysis; D001835:Body Weight; D018592:Cross-Over Studies; D015633:Extravascular Lung Water / Q000502:physiology*; D005260:Female; D006612:High-Frequency Ventilation / Q000379:methods* / Q000706:statistics & numerical data; D006801:Humans; D007327:Insufflation / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011654:Pulmonary Edema / Q000503:physiopathology / Q000517:prevention & control*; D012119:Respiration; D012128:Respiratory Distress Syndrome / Q000503:physiopathology / Q000628:therapy*
keywords: Acute respiratory distress syndrome; Extravascular lung water; High-frequency ventilation