The current study shows that compared to plain water, the commercial carbohydrate beverage, Resource® given pre-gastroscopy resulted in higher gastric residual volume (GRV) post-gastroscopy. Our study demonstrated a higher GRV after carbohydrate load, different from a previously reported study [10]. The gastric residual volume was measured via direct aspiration during gastroscopy; a more accurate measurement than other indirect measurements for example dilutional or aspiration from the nasogastric tube [1, 10]. However, this method might overestimate gastric residual volume. None of participants were obese and BMIs were similar at baseline in both groups, however obesity was not found to be a confounding factor in a study [13], although insulin resistance was not investigated in the current study.
The carbohydrate beverage used in this study was Resource® (Nestle Health Science, Malaysia), consisting of 53.6 g of carbohydrate in the form of maltodextrin. To achieve adequate induction of insulin release and shift body metabolism from fasting to a fed state, 50g of carbohydrate is sufficient [5]. Polymer and low osmolality carbohydrates including maltodextrin have been shown to reduce gastric emptying time [8]. However, a study comparing the gastric emptying rate of water and protein drinks in older men and women concluded that higher protein content drinks significantly reduced the gastric emptying rate [14]. With Resource®, the 9g of whey protein might contribute to higher GRV by reducing gastric emptying. In addition, higher osmolality beverage also delay gastric emptying [15, 16], and with an osmolality of 770 mOsm/kg H2O in Resource®, this could be another contributing factor to a higher GRV.
Prolonged fasting imposes stress on patients both physiologically and psychologically. Carbohydrate loading provides energy and fluid replenishment while reducing anxiety and lethargy related to fasting [10]. This explains why only anxiety but not other variables of well-being was significantly reduced after carbohydrate beverage. In addition, there was less hunger and thirst with carbohydrate beverage after adjustment for BMI, age, and time interval for drinks to procedure. Other studies have also reported that carbohydrate loading improved hunger and thirst [10, 17, 18].
There were no reported adverse events during the study. There was no pulmonary aspiration, failed or incomplete endoscopy secondary to overt GRV or choking. Although group B had higher GRV, there was no evidence of choking or aspiration. This finding reassures that usage of carbohydrate and clear fluid up to 2 hours prior to gastroscopy is relatively safe [19].
There are study limitations. Participants with comorbidities such as diabetes mellitus, chronic kidney disease, gastro-oesophageal reflux disease and acute gastritis were not excluded, and these conditions might cause delayed gastric emptying. An ideal carbohydrate load should be free from protein or hyperosmolar additives which may affect gastric emptying however such ideal beverage is not commercially available.
In conclusion, carbohydrate beverage results in higher GRV post-procedure, reduces anxiety post-procedure, and improves hunger and thirst after adjustment for confounding factors. The beverage given pre-procedure does not result in adverse events post-procedure.