http://annals.org/ en-us Tue, 19 Mar 2013 00:00:00 GMT Tue, 09 Apr 2013 13:46:34 GMT Silverchair editor@annals.org webmaster@annals.org http://annals.org/article.aspx?articleID=1666738 Tue, 19 Mar 2013 00:00:00 GMT Hill NS. <span class="paragraphSection"><div class="boxTitle">Question</div>In ventilated patients without acute lung injury or the acute respiratory distress syndrome (ARDS), does protective ventilation with lower tidal volumes (V_T) improve outcomes compared with conventional ventilation?<div class="boxTitle">Review scope</div>Included studies compared protective ventilation (lower V_T) with conventional ventilation (higher V_T) in patients who did not meet the consensus criteria for ARDS or acute lung injury and reported on the outcomes of interest, including lung injury {as defined by individual studies, but usually development of acute lung injury}*, mortality, pulmonary infection, atelectasis, time on ventilation, and durations of intensive care unit (ICU) and hospital stays.<div class="boxTitle">Review methods</div>MEDLINE, CINAHL, Web of Science, and Cochrane Central Register of Controlled Trials (all to Aug 2012) were searched for randomized controlled trials (RCTs) and observational studies. 20 studies (<span style="font-style:italic;">n</span> = 2822, mean age 60 y at final visit), including 15 RCTs (<span style="font-style:italic;">n</span> = 925) and 5 observational studies (<span style="font-style:italic;">n</span> = 1897), met the selection criteria. All RCTs scored ≤ 3 on the 5-point Jadad quality assessment scale. Study settings included general ICUs, surgical units, and oncology surgery (4 studies each); coronary artery bypass graft surgery (3 studies); surgical ICUs and cardiac surgery (2 studies each); and neurosurgery (1 study). Ventilation in the protective group was mean V_T 6.45 mL/kg ideal body weight (IBW) (5 to 9 mL/kg IBW) for a median of 6.90 hours and in the conventional group was mean V_T 10.60 mL/kg IBW (9 to 12 mL/kg IBW) for a median of 6.56 hours. Median follow-up time was 21 hours where reported. 6 of 8 RCTs that reported lung injury used the American-European Consensus Conference definition for the outcome.<div class="boxTitle">Main results</div>Meta-analysis showed that protective ventilation reduced lung injury, mortality, pulmonary infection, and atelectasis compared with conventional ventilation (Table). Protective ventilation reduced length of hospital stay (mean 6.9 vs 8.9 d, <span style="font-style:italic;">P</span> = 0.001) but not time on mechanical ventilation (mean 51 vs 47 h, <span style="font-style:italic;">P</span> = 0.21) nor length of ICU stay (mean 3.6 vs 4.6 d, <span style="font-style:italic;">P</span> = 0.42).<div class="boxTitle">Conclusion</div>Protective ventilation with lower tidal volumes reduces lung injury and mortality compared with conventional ventilation in patients without the acute respiratory distress syndrome.Protective vs conventional ventilation in patients without the acute respiratory distress syndrome†OutcomesNumber of trials (<span style="font-style:italic;">n</span>)Weighted event ratesAt a median 21 hProtectiveConventionalRRR (95% CI)NNT (CI)Lung injury8 (2203)4.5%13%64% (49 to 75)13 (11 to 17)Mortality9 (2222)7.0%11%35% (9 to 53)27 (18 to 99)Pulmonary infection4 (1346)4.0%8.6%54% (8 to 77)22 (16 to 153)Atelectasis5 (1287)6.2%9.8%37% (5 to 59)28 (18 to 214)†Abbreviations defined in Glossary. RRR, NNT, and CI calculated from control event rates and relative risks in article using a random-effects model.</span> http://annals.org/article.aspx?articleID=1666738