title: Mechanistic scheme and effect of "extended sigh" as a recruitment maneuver in patients with acute respiratory distress syndrome: a preliminary study.
abstract: OBJECTIVE
  To devise a new form of sigh ("extended sigh") capable of providing a sufficient recruiting pressure x time, and to test it as a recruitment maneuver in patients with acute respiratory distress syndrome.
  
  
  METHODS
  Prospective uncontrolled clinical trial.
  
  
  METHODS
  Medical intensive care unit of a university-affiliated hospital.
  
  
  METHODS
  Twenty consecutive patients diagnosed with acute respiratory distress syndrome (18 men, 2 women, age 59 +/- 10 yrs).
  
  
  METHODS
  From baseline settings of tidal volume (Vt) 8 mL/kg and positive end-expiratory pressure (PEEP) 10 cm H2O on volume control mode with the high pressure limit at 40 cm H2O, the Vt-PEEP values were changed to 6-15, 4-20, and 2-25, each step being 30 secs (inflation phase). After Vt-PEEP 2-25, the mode was switched to continuous positive airway pressure of 30 cm H2O for a duration of 30 secs (pause), after which the baseline setting was resumed following the reverse sequence of inflation (deflation phase). This extended sigh was performed twice with 1 min of baseline ventilation between.
  
  
  RESULTS
  Airway pressures and hemodynamic parameters were traced at each step during the extended sigh. Arterial blood gases and physiologic parameters were determined before the extended sigh (pre-extended sigh), at 5 mins after two extended sighs (post-extended sigh), and then every 15 mins for 1 hr. In our average patient, the recruiting pressure x time of the inflation phase was estimated to be 32.8-35.4 cm H2O x 90 secs. Compared with the inflation phase, inspiratory pause pressure of the deflation phase was lower at Vt-PEEP 6-15 (28.9 +/- 2.7 cm H2O vs. 27.3 +/- 2.8 cm H2O) and 4-20 (31.8 +/- 2.9 cm H2O vs. 31.1 +/- 2.9 cm H2O; both p <.05). Compared with pre-extended sigh, Pao2 (81.5 +/- 15.3 mm Hg vs. 104.8 +/- 25.0 mm Hg; p <.001) and static respiratory compliance both increased post-extended sigh (27.9 +/- 7.9 mL/cm H2O vs. 30.2 +/- 9.7 mL/cm H2O; p =.009). Improvement in these parameters was sustained above pre-extended sigh for the duration of the study. Major hemodynamic or respiratory complications were not noted during the study.
  
  
  CONCLUSIONS
  We present a new form of sigh (i.e., extended sigh) capable of achieving an augmented recruiting pressure x time through a prolonged inflation on a gradually increased end-expiratory pressure. In view of the sustained effect and absence of major complications in our patients, extended sigh could be a useful recruitment maneuver in acute respiratory distress syndrome.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea. cmlim@www.amc.seoul.kr
authors.forename: C M
authors.initials: CM
authors.lastname: Lim
authors.forename: Y
authors.initials: Y
authors.lastname: Koh
authors.forename: W
authors.initials: W
authors.lastname: Park
authors.forename: J Y
authors.initials: JY
authors.lastname: Chin
authors.forename: T S
authors.initials: TS
authors.lastname: Shim
authors.forename: S D
authors.initials: SD
authors.lastname: Lee
authors.forename: W S
authors.initials: WS
authors.lastname: Kim
authors.forename: D S
authors.initials: DS
authors.lastname: Kim
authors.forename: W D
authors.initials: WD
authors.lastname: Kim
mesh_terms: D000403:Airway Resistance; D005260:Female; D006439:Hemodynamics; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000378:metabolism; D011175:Positive-Pressure Respiration; D011446:Prospective Studies; D012128:Respiratory Distress Syndrome / Q000503:physiopathology*; D015656:Respiratory Mechanics / Q000502:physiology*; D018709:Statistics, Nonparametric; D013990:Tidal Volume
chemical_list: D010100:Oxygen