Fig. 3

Boxplot displaying changes of the oxygenation saturation index after lung recruitment for different groups of lung recruitment indication. On each box, the central line indicates the median, and the bottom and top edges represent the 25th and 75th percentiles, respectively. The whiskers extend to the most extreme data points within two times the interquartile range. The ‘+’ symbol indicates the outliers. No statistically significant difference could be found among the groups