title: Tidal volume lower than 6 ml/kg enhances lung protection: role of extracorporeal carbon dioxide removal.
abstract: BACKGROUND
  Tidal hyperinflation may occur in patients with acute respiratory distress syndrome who are ventilated with a tidal volume (VT) of 6 ml/kg of predicted body weight develop a plateau pressure (PPLAT) of 28 < or = PPLAT < or = 30 cm H2O. The authors verified whether VT lower than 6 ml/kg may enhance lung protection and that consequent respiratory acidosis may be managed by extracorporeal carbon dioxide removal.
  
  
  METHODS
  PPLAT, lung morphology computed tomography, and pulmonary inflammatory cytokines (bronchoalveolar lavage) were assessed in 32 patients ventilated with a VT of 6 ml/kg. Data are provided as mean +/- SD or median and interquartile (25th and 75th percentile) range. In patients with 28 < or = PPLAT < or = 30 cm H2O (n = 10), VT was reduced from 6.3 +/- 0.2 to 4.2 +/- 0.3 ml/kg, and PPLAT decreased from 29.1 +/- 1.2 to 25.0 +/- 1.2 cm H2O (P < 0.001); consequent respiratory acidosis (Paco2 from 48.4 +/- 8.7 to 73.6 +/- 11.1 mmHg and pH from 7.36 +/- 0.03 to 7.20 +/- 0.02; P < 0.001) was managed by extracorporeal carbon dioxide removal. Lung function, morphology, and pulmonary inflammatory cytokines were also assessed after 72 h.
  
  
  RESULTS
  Extracorporeal assist normalized Paco2 (50.4 +/- 8.2 mmHg) and pH (7.32 +/- 0.03) and allowed use of VT lower than 6 ml/kg for 144 (84-168) h. The improvement of morphological markers of lung protection and the reduction of pulmonary cytokines concentration (P < 0.01) were observed after 72 h of ventilation with VT lower than 6 ml/kg. No patient-related complications were observed.
  
  
  CONCLUSIONS
  VT lower than 6 ml/Kg enhanced lung protection. Respiratory acidosis consequent to low VT ventilation was safely and efficiently managed by extracorporeal carbon dioxide removal.
authors.affiliation: Dipartimento di Anestesiologia e Medicina degli Stati Critici, Università di Torino, Ospedale S. Giovanni Battista-Molinette, Corso Dogliotti 14, Turin, Italy.
authors.forename: Pier Paolo
authors.initials: PP
authors.lastname: Terragni
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Del Sorbo
authors.forename: Luciana
authors.initials: L
authors.lastname: Mascia
authors.forename: Rosario
authors.initials: R
authors.lastname: Urbino
authors.forename: Erica L
authors.initials: EL
authors.lastname: Martin
authors.forename: Alberto
authors.initials: A
authors.lastname: Birocco
authors.forename: Chiara
authors.initials: C
authors.lastname: Faggiano
authors.forename: Michael
authors.initials: M
authors.lastname: Quintel
authors.forename: Luciano
authors.initials: L
authors.lastname: Gattinoni
authors.forename: V Marco
authors.initials: VM
authors.lastname: Ranieri
mesh_terms: D000142:Acidosis, Respiratory / Q000628:therapy; D000368:Aged; D000399:Air Pressure; D002245:Carbon Dioxide / Q000097:blood / Q000302:isolation & purification*; D002302:Cardiac Output / Q000502:physiology; D016207:Cytokines / Q000097:blood; D015199:Extracorporeal Membrane Oxygenation; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008168:Lung / Q000000981:diagnostic imaging / Q000473:pathology; D008171:Lung Diseases / Q000473:pathology / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D011014:Pneumonia / Q000473:pathology; D011175:Positive-Pressure Respiration; D012121:Respiration, Artificial / Q000009:adverse effects; D012128:Respiratory Distress Syndrome / Q000628:therapy; D012129:Respiratory Function Tests; D013990:Tidal Volume / Q000502:physiology*; D014057:Tomography, X-Ray Computed
chemical_list: D016207:Cytokines; D002245:Carbon Dioxide