Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Pneumonia
RCT	200 people having hepatic resection	Pneumonia 5/100 (5%) with removal of the nasogastric tube at the end of the operation (selective use) 13/100 (13%) with routine nasogastric decompression	P = 0.047	Effect size not calculated	selective use
Postoperative pulmonary complications (unspecified)
Systematic review	2892 people who had undergone abdominal surgery 19 RCTs in this analysis	Pulmonary complications (pneumonia or atelectasis, or both) 148/1448 (10%) with routine nasogastric tube gastric decompression 104/1444 (7%) with selective postoperative nasogastric decompression	RR (for fewer complications) 1.35 95% CI 0.98 to 1.86 P = 0.07		Not significant
RCT	316 people having surgery for colorectal carcinoma	Postoperative pulmonary infection (not further defined) 1/161 (1%) with removal of the nasogastric tube 12–24 hours after surgery (selective use) 7/155 (5%) with routine nasogastric decompression	P = 0.034 The method of randomisation and length of follow-up of the RCT were unclear	Effect size not calculated	selective use
RCT	40 people having surgery of the infrarenal aorta	Postoperative respiratory complications (not further defined) 0/20 (0%) with removal of the nasogastric tube at the time of tracheal extubation (selective use) 5/20 (25%) with routine use	P = 0.023 The method of randomisation and length of follow-up of the RCT were unclear	Effect size not calculated	selective use