Table 1: Main characteristics of RCTs for surgical patients included in this study.

AuthorYearSurgeryLow PEEP levelHigh PEEP level

Tusman et al. [21]1999Neurosurgical0 cm H2O10 cm H2O
Neumann et al. [22]1999Abdominal0 cm H2O10 cm H2O
Wetterslev et al. [24]2001Abdominal0 cm H2OBest PEEP
Meininger et al. [25]2005Laparoscopic0 cm H2O 5 cm H2O
Whalen et al. [27]2006Laparoscopic4 cm H2O 12 cm H2O
Talab et al. [29]2009Laparoscopic bariatric0 cm H2O5–10 cm H2O
Reinius et al. [30]2009Bariatric 0 cm H2O10 cm H2O
Kim et al. [26]2010Laparoscopic0 cm H2O 5 cm H2O
Futier et al. [31]2013Abdominal0 cm H2O 6–8 cm H2O
Severgnini et al. [32]2013Abdominal0 cm H2O10 cm H2O