Physiological impact of oral carbohydrate preload in healthy volunteers

Oral carbohydrate loading has become a key component of Enhanced Recovery After Major Surgery (ERAS) pathways, with potential improvements in patient comfort, nausea and vomiting, ileus and length of stay. The contribution of each component of ERAS, including carbohydrate beverages, remains unclear. We aimed to determine the impact of standardized oral carbohydrate fluid loading on haemodynamics, stroke volume and gastric state in a group of healthy volunteers.

Twenty-three volunteer participants free of known cardiovascular or gastrointestinal disease, consumed 400 mL of a proprietary carbohydrate solution. Heart rate (HR), blood pressure (BP), stroke volume (SV) and gastric cross-sectional area (CSA) were measured with bedside ultrasound at baseline, 30/60/120 min post-ingestion.

There were small decreases in HR, BP (<10%) that were statistically significant. There were small increases (<10%) in SV at 30 and 60 min post-ingestion, but SV had returned to baseline by 120 min. There were no changes in SV variation. Gastric CSA increased immediately post-ingestion, then decreased in a linear fashion before returning to baseline by 120 min.

In a standard 400 mL dose of a carbohydrate beverage, only small increases in SV could be demonstrated in the first-hour post-ingestion. All patients had largely returned to their baseline SV and gastric CSA state within 2 h post-fluid ingestion. A mild decrease in HR and BP was noted that persisted at 120 min. A 400 mL carbohydrate beverage does not appear to have favourable cardiovascular effects in a healthy population.