Outcome/Subgroup	Studies	Number (n/N)	MD (BLD–GLD)	SE (MD)	Effect estimate (95% CI)	Z test
MD in PaO2 after turning	4	35			See meta‐analysis (subgroup data not included).
4.5.1. subgroup with left lung atelectasis at 10 minutes after turn	Banasik 1987	10/60	‐11.8	4.6	‐11.80 (‐20.82 to ‐2.78)	2.57 (P value = 0.01)
4.5.2. a,bMD in PaO2 at 10 minutes after turn	Remolina 1981	9	‐40.888	13.217	‐40.89 (‐66.79 to ‐14.98)	3.09 (P value = 0.002)
4.5.3. aMD in PaO2 at 15 minutes after turn	Ibanez 1981	10	‐57.2	12.878	‐57.20 (‐82.44 to ‐31.96)	4.44 (P value < 0.00001)
4.5.4. aSubgroup with unilateral atelectasis at 30 minutes after turn	Chan 1992	6/30	0.333	4.558	0.33 (‐8.60 to 9.27)	0.07 (P value = 0.94)