title: Ventilation with lower tidal volumes versus traditional tidal volumes in adults for acute lung injury and acute respiratory distress syndrome.
abstract: BACKGROUND
  Patients with acute respiratory distress syndrome (ARDS) and acute lung injury (ALI) require mechanical ventilatory support. ALI/ARDS is further complicated by ventilator-induced lung injury. Lung-protective ventilation strategies may lead to improved survival.
  
  
  OBJECTIVE
  To assess the effects of ventilation with lower tidal volume (Vt) on morbidity and mortality in adults patients affected by ALI/ARDS. A secondary objective was to determine whether the comparison between low and conventional Vt is different if a plateau airway pressure of greater than 30 to 35 cm H20 was used.
  
  
  METHODS
  We searched The Cochrane Central Register of Controlled Trials (CENTRAL), The Cochrane Library issue 3, 2002; MEDLINE (1966 to June 2002); EMBASE and CINAHL (1982 to June 2002); intensive care journals and conference proceedings; databases of ongoing research, reference lists and 'grey literature'.
  
  
  METHODS
  Randomized trials comparing ventilation using lower Vt and/or low airway driving pressure (plateau pressure 30 cm H2O or less), resulting in Vt of 7 ml/kg or less versus ventilation that uses Vt in the range of 10 to 15 ml/kg, in adults (16 year-old or greater).
  
  
  METHODS
  Two reviewers independently assessed trial quality and extracted data. Wherever appropriate, results were pooled. Fixed and random effects models were applied.
  
  
  RESULTS
  Five trials, involving 1202 patients, were eligible. The test for heterogeneity gave a P-value of 0.12. Ventilation with lower Vt was associated with a decreased mortality at the end of the follow up period for each trial: 216/605 (35.7%) versus 249/597 (41.7%), relative risk (RR) 0.85 (CI 0.74 to 0.98). The effect of the intervention was not statistically significant when a random effects model was used: RR 0.91 (CI 0.72 to 1.14). Mortality at day 28 was significantly reduced by lung-protective ventilation: RR 0.74 (CI 0.61 to 0.88). The comparison between low and conventional Vt was not significantly different if a plateau pressure less than or equal to 31 cm H2O in control group was used: RR 1.13 (CI 0.88 to 1.45). There was insufficient evidence about morbidity and long term outcomes.
  
  
  CONCLUSIONS
  Clinical heterogeneity, such as different lengths of follow up and higher plateau pressure in control arms in two trials make the interpretation of the combined results difficult. Mortality is significantly reduced at day 28 and the effects on long term mortality are uncertain, although the possibility of a clinically relevant benefit cannot be excluded. There is no evidence that low Vt ventilation is beneficial in patients where hypercapnia is potentially harmful.
authors.affiliation: Department of Anaesthesia and Intensive care, Azienda Ospedaliera Desenzano, Loc. Montecroce, Desenzano (BS), Italy.
authors.forename: N
authors.initials: N
authors.lastname: Petrucci
authors.forename: W
authors.initials: W
authors.lastname: Iacovelli
mesh_terms: D000328:Adult; D006801:Humans; D016032:Randomized Controlled Trials as Topic; D012121:Respiration, Artificial / Q000379:methods*; D012128:Respiratory Distress Syndrome / Q000401:mortality / Q000628:therapy*; D013990:Tidal Volume