Liberal fluid fasting: impact on gastric pH and residual volume in healthy children undergoing general anaesthesia for elective surgery

Abstract

Background: The paediatric preoperative fasting time of 2 h for clear fluids, as suggested by guidelines, is often exceeded. Shorter preoperative fasting has been proposed to avoid potential outcomes such as dehydration, ketoacidosis, reduced arterial blood pressure, and patient discomfort. The aim of this study was to investigate whether liberal clear fluid intake until premedication significantly reduces actual fasting time and impacts gastric pH and residual volume.

Methods: Children (1-16 yr old, ASA I or II) undergoing elective procedures with general anaesthesia requiring tracheal intubation were randomised for clear fluid intake until premedication with midazolam (liberal) or 2 h fluid fasting (standard). Actual fasting times were recorded. Gastric content was sampled after tracheal intubation with an orogastric tube to determine gastric pH and residual volume. Data are presented as median [interquartile range].

Results: We included 162 children aged 1.1-16 yr; gastric pH was determined in 138 patients. Patients' characteristics were similar in the two groups. The liberal fasting group had significantly shorter fasting times (48 [18.5-77.5] vs 234 [223.5-458.5] min; P<0.001). No significant difference was observed regarding gastric pH (1.6 [1.5-1.8] vs 1.6 [1.4-1.7]; P=0.237) or residual volume (0.38 [0.1-1.1] vs 0.43 [0.13-0.73] ml kg^-1; P=0.535). Twelve patients (15%) in the liberal group (median fluid fasting 32 min) vs one patient (1%) had gastric residual volumes >2 ml kg^-1 (P=0.001).

Conclusion: Fluid intake until premedication allows for significantly shorter fasting times. Elevated gastric residual volumes may occur more often in patients with fasting times of 30 min or shorter.

Clinical trial registration: NCT02603094.

Keywords: anesthesia, general; child; fasting; residual volume.