Comparison	Outcome	Result	Analysis
NIV compared to oxygen	pH	MD 0.00 (95% CI ‐0.03 to 0.03)	Analysis 2.7
	PaO₂	MD ‐4.00 mmHg (95% CI ‐13.43 to 5.43)	Analysis 2.8
	PaCO₂	MD ‐1.00 mmHg (95% CI ‐7.10 to 5.10)	Analysis 2.9
	HCO₃	MD 0.00 mmol/L (95% CI ‐3.14 to 3.14)	Analysis 2.10
	SaO₂ %	MD ‐2.00 % (95% CI ‐6.06 to 2.06)	Analysis 2.11
NIV compared to room air	pH	MD 0.01 (95% CI ‐0.02 to 0.04)	Analysis 3.9
	PaO₂	MD ‐2.00 mmHg (95% CI ‐8.58 to 4.58)	Analysis 3.10
	PaCO₂	MD ‐2.00 mmHg (95% CI ‐8.10 to 4.10)	Analysis 3.11
	HCO₃	MD 0.00 mmol/L (95% CI ‐2.55 to 2.55)	Analysis 3.12
	SaO₂ %	MD ‐1.00 % (95% CI ‐4.62 to 2.6)	Analysis 3.13