Small bowel feeding and risk of pneumonia in adult critically ill patients: a systematic review and meta-analysis of randomized trials

Introduction: This systematic review and meta-analysis aimed to evaluate the effect of small bowel feeding compared with gastric feeding on the frequency of pneumonia and other patient-important outcomes in critically ill patients. Methods: We searched EMBASE, MEDLINE, clinicaltrials.gov and personal files from 1980 to Dec 2012, and conferences and proceedings from 1993 to Dec 2012 for randomized trials of adult critically ill patients in the intensive care unit (ICU) comparing small bowel feeding to gastric feeding, and evaluating risk of pneumonia, mortality, length of ICU stay, achievement of caloric requirements, duration of mechanical ventilation, vomiting, and aspiration. Independently, in duplicate, we abstracted trial characteristics, outcomes and risk of bias. Results: We included 19 trials with 1394 patients. Small bowel feeding compared to gastric feeding was associated with reduced risk of pneumonia (risk ratio [RR] 0.70; 95% CI, 0.55, 0.90; P = 0.004; I-2 = 0%) and ventilator-associated pneumonia (RR 0.68; 95% CI 0.53, 0.89; P = 0.005; I-2 = 0%), with no difference in mortality (RR 1.08; 95% CI 0.90, 1.29; P = 0.43; I-2 = 0%), length of ICU stay (WMD -0.57; 95% CI -1.79, 0.66; P = 0.37; I-2 = 0%), duration of mechanical ventilation (WMD -1.01; 95% CI -3.37, 1.35; P = 0.40; I-2 = 17%), gastrointestinal bleeding (RR 0.89; 95% CI 0.56, 1.42; P = 0.64; I-2 = 0%), aspiration (RR 0.92; 95% CI 0.52, 1.65; P = 0.79; I-2 = 0%), and vomiting (RR 0.91; 95% CI 0.53, 1.54; P = 0.72; I-2 = 57%). The overall quality of evidence was low for pneumonia outcome. Conclusions: Small bowel feeding, in comparison with gastric feeding, reduces the risk of pneumonia in critically ill patients without affecting mortality, length of ICU stay or duration of mechanical ventilation. These observations are limited by variation in pneumonia definition, imprecision, risk of bias and small sample size of individual trials.