Chapple LS1,2, Summers MJ1,2, Weinel L1,2, Ali Abdelhamid Y1,3, Kar P1, Calnan D4, Hatzinikolas S5, Lange K5, Poole A1, O’Connor S2, Horowitz M5, Jones KL5, Deane A3,5, Chapman M1,2.

1Discipline of Acute Care Medicine, University of Adelaide, 2Intensive Care Unit, Royal Adelaide Hospital, CALHN, SA Health, 3Intensive Care Unit, The Royal Melbourne Hospital, Victoria, 4Nuclear Medicine, Royal Adelaide Hospital, CALHN, SA Health, 5Discipline of Medicine, University of Adelaide


Background: Enteral Feeding (tube feeding) is standard care in critically ill mechanically ventilated patients. Critically ill patients frequently exhibit delayed gastric emptying and associated feed intolerance, which are frequently managed by the prescription of energy-dense formulae. However, these formulae have a higher fat content and may delay gastric emptying (GE) further.

Aim:  To compare the rate of GE of isocaloric 1 and 2 kcal/ml liquid nutrient boluses in critically ill patients.

Methods:  A randomised, blinded, cross-over study was performed in mechanically ventilated adults on two consecutive days. Following a four hour fast, in random order, patients received an isocaloric, radiolabeled, intragastric bolus via naso-gastric tube of either 200ml of a 1kcal/ml or 100ml of a 2kcal/ml enteral formula. GE was measured using scintigraphy. Total areas under the curve from baseline to 120 minutes (AUC120) were determined for gastric retention and small intestinal calorie delivery. Group differences were compared using a paired mixed effects model. Data are presented as mean ± SE.

Results:  Eighteen patients were studied (M:F 14:4; age 55.2 ± 5.3 years). Gastric retention at 120min was greater with the energy-dense formula (standard: 17.0±5.9 vs energy-dense: 32.5±7.1; difference 12.7 (90% CI 0.8–30.1) %). Caloric delivery was not improved with the energy-dense formula (AUC120: 13038±1119 vs 9763±1346 kcal/120min; P=0.057).

Conclusion:  In critical illness, administration of an energy-dense formula does not reduce gastric retention, increase calorie delivery to the small intestine, nor improve glucose absorption or glucose control; instead, there is a signal for delayed gastric emptying.

Matt is a Research Dietitian who has been working within the ICU Research team for over 10 years. Matt completed his undergraduate Bachelor of Science majoring in nutrition in 2007 and commenced a Research Scientist role within ICU Research shortly thereafter. A few years later Matt undertook a Master of Dietetics, graduating in 2014.

Matt’s research interests include nutrient absorption in critically ill patients, as well as nutritional intake and outcomes following ICU stay. In addition to research experience in ICU, Matt has experience as a clinical dietitian in the outpatient setting as well as dietitian experience in the elite team sport environment.

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