Background & aims: Preoperative starvation has many undesirable effects but the minimum length of fasting is limited by gastric emptying, which may be dependent on nutrient content, viscosity and osmolarity of the feed. We compared the gastric emptying of two types of preoperative metabolic preconditioning drinks [Oral Nutritional Supplement (ONS) (Fresenius Kabi, Germany) and preOp® (Nutricia Clinical Care, UK)] in healthy volunteers. Methods: Twenty (10 male, 10 female) healthy adult volunteers were studied on 3 separate occasions in a randomised crossover manner. Volunteers ingested 400 ml preOp®, which is a clear carbohydrate drink (CCD) (50 g carbohydrate, 0 g protein), 70 g ONS (50 g carbohydrate and 15 g glutamine) dissolved in water to a total volume of 400 ml (ONS400) and 300 ml (ONS300). Gastric emptying time was measured using magnetic resonance imaging. Results: Mean (95% CI) T50 and T100 gastric emptying times for CCD were significantly lower (p < 0.001) compared with ONS400 and ONS300. T50 was 47 (39-55), 78 (69-87) and 81 (70-92) min for CCD, ONS400 and ONS300 respectively. Correspondingly T100 was 94 (79-110), 156 (138-173) and 162 (140-184) min. Residual gastric volumes returned to baseline 120 min after CCD and 180 min after ONS400 and ONS300. Conclusions: The faster gastric emptying for CCD compared to ONS400 and ONS300 signifies that gastric emptying may be more dependent on nutrient load than volume or viscosity in healthy volunteers. While it is safe to give CCD 2 h preoperatively, ONS400 and ONS300 should be given at least 3 h preoperatively.
All Science Journal Classification (ASJC) codes
- Nutrition and Dietetics
- Critical Care and Intensive Care Medicine