Fig.4From: The effectiveness of high-flow nasal cannula during sedated digestive endoscopy: a systematic review and meta-analysisSubgroup analysis of hypoxemia incidence between high-flow nasal cannula oxygen (HFNC) and standard nasal cannula oxygen (SNC). hypoxemia was defined as SpO2 < 90%. A Low hypoxemia risk subjects; B High hypoxemia risk subjects. CI confidence interval, M–H Mantel–HaenszelBack to article page