Definitions

AGI was defined as a malfunction of the GI tract in critically ill patients due to acute illness and was categorised into four grades according to its severity.³ Primary AGI was associated with primary disease or direct injury to organs of the GI system, for example, peritonitis, pancreatic or hepatic pathology, abdominal surgery and abdominal trauma.³ Secondary AGI developed as the consequence of a host response in critical illness without primary pathology in the GI system, for example, GI malfunction in a patient with pneumonia, cardiac pathology, non-abdominal surgery or trauma.³ AGI grade I was defined as an increased risk of developing GI dysfunction or failure (a self-limiting condition); AGI grade II was defined as GI dysfunction (a condition that requires interventions); AGI grade III was defined as GI failure (GI function cannot be restored with interventions) and AGI grade IV was defined as dramatically manifesting GI failure (a condition that is immediately life-threatening).³ In this study, we determined AGI grade II or above as severe AGI. Total enteral nutrition (TEN) was defined as full (at least 20 kcal/kg body weight (BW)/day within 72 hours of feeding^{3 9}) enteral nutrition via nasogastric or nasojejunal tube. AGI deterioration was defined as AGI grade from 0 to I/II/III, from I to II/III or from II to III. GI symptoms included nausea, vomiting, diarrhoea, paralysis, high gastric residual volumes, intra-abdominal hypertension and GI bleeding.³ Feeding intolerance (FI) syndrome was a general term indicating intolerance of enteral feeding for whatever clinical reasons, and FI was also considered present if at least 20 kcal/kg BW/day via the enteral route could not be reached within 72 hours of a feeding attempt.³ Sepsis was defined as life-threatening organ dysfunction caused by a dysregulated host response to infection.⁹ The diagnostic criteria of ARDS were in accordance with the Berlin definitions.¹⁰ The definitions of AKI were based on the 2012 Kidney Disease: Improving Global Outcomes guidelines.¹¹ MODS was defined as the combined dysfunction of two or more organs.