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 preOpยฎ (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 400ml preOpยฎ, which is a clear carbohydrate drink (CCD) (50g carbohydrate, 0g protein), 70g ONS (50g carbohydrate and 15g glutamine) dissolved in water to a total volume of 400ml (ONS400) and 300ml (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 (39โ55), 78 (69โ87) and 81 (70โ92)min for CCD, ONS400 and ONS300 respectively. Correspondingly T100 was 94 (79โ110), 156 (138โ173) and 162 (140โ184)min. Residual gastric volumes returned to baseline 120min after CCD and 180min 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 2h preoperatively, ONS400 and ONS300 should be given at least 3h preoperatively.