title: Tidal volume and mortality in mechanically ventilated children: a systematic review and meta-analysis of observational studies*.
abstract: OBJECTIVE
  To determine whether tidal volume is associated with mortality in critically ill, mechanically ventilated children.
  
  
  METHODS
  MEDLINE, EMBASE, and CINAHL databases from inception until July 2013 and bibliographies of included studies without language restrictions.
  
  
  METHODS
  Randomized clinical trials and observational studies reporting mortality in mechanically ventilated PICU patients.
  
  
  METHODS
  Two authors independently selected studies and extracted data on study methodology, quality, and patient outcomes. Meta-analyses were performed using the Mantel-Haenszel random-effects model. Heterogeneity was quantified using I. Study quality was assessed using the Newcastle-Ottawa Score for cohort studies.
  
  
  RESULTS
  Out of 142 citations, seven studies met the inclusion criteria, and additional two articles were identified from references of the found articles. One was excluded. These eight studies included 1,756 patients. Mortality rates ranged from 13% to 42%. There was no association between tidal volume and mortality when tidal volume was dichotomized at 7, 8, 10, or 12 mL/kg. Comparing patients ventilated with tidal volume less than 7 mL/kg and greater than 10 mL/kg or greater than 12 mL/kg and tidal volume less than 8 mL/kg and greater than 10 mL/kg or greater than 12 mL/kg also showed no association between tidal volume and mortality. Limiting the analysis to patients with acute lung injury/acute respiratory distress syndrome did not change these results. Heterogeneity was observed in all pooled analyses.
  
  
  CONCLUSIONS
  A relationship between tidal volume and mortality in mechanically ventilated children could not be identified, irrespective of the severity of disease. The significant heterogeneity observed in the pooled analyses necessitates future studies in well-defined patient populations to understand the effects of tidal volume on patient outcome.
authors.affiliation: 1Division of Paediatric Intensive Care, Department of Paediatrics, Beatrix Children's Hospital, University Medical Center Groningen, Groningen, The Netherlands. 2Department of Epidemiology, University Medical Center Groningen, Groningen, The Netherlands. 3Department of Paediatric Intensive Care, VU University Medical Center, Amsterdam, The Netherlands. 4St. Elisabeth Hospital, Tilburg, The Netherlands. 5Critical Care, Anaesthesiology, Peri-operative Medicine and Emergency Medicine, the University of Groningen, Groningen, The Netherlands.
authors.forename: Pauline
authors.initials: P
authors.lastname: de Jager
authors.forename: Johannes G M
authors.initials: JG
authors.lastname: Burgerhof
authors.forename: Marc
authors.initials: M
authors.lastname: van Heerde
authors.forename: Marcel J I J
authors.initials: MJ
authors.lastname: Albers
authors.forename: Dick G
authors.initials: DG
authors.lastname: Markhorst
authors.forename: Martin C J
authors.initials: MC
authors.lastname: Kneyber
mesh_terms: D055371:Acute Lung Injury / Q000401:mortality; D016638:Critical Illness / Q000401:mortality*; D006801:Humans; D015278:Intensive Care Units, Pediatric / Q000706:statistics & numerical data*; D012121:Respiration, Artificial / Q000379:methods*; D012720:Severity of Illness Index; D013990:Tidal Volume