Optimal volumes of early oral fluid intake in the post-anesthesia care unit for patients not under postoperative fasting orders: a meta-analysis and trial sequential analysis of clinical recovery and safety outcomes.

INTRODUCTION: Postoperative recovery in the post-anaesthesia care unit (PACU) is frequently complicated by thirst, oropharyngeal dryness, and postoperative nausea and vomiting (PONV). Early oral fluid intake has been proposed to alleviate these discomforts. However, its optimal timing and volume remain uncertain. We conducted a systematic review and meta-analysis with trial sequential analysis (TSA) to evaluate the safety and clinical outcomes of PACU-initiated early oral fluid intake in adults after general anaesthesia, focusing on administered fluid volume.

METHODS: We systematically searched PubMed/MEDLINE, Embase, CENTRAL, Ovid, Web of Science, and Wanfang Database for studies published from January 2014 to December 2024. Eligible studies enrolled adults (≥18 years) recovering in the PACU after general anaesthesia who received early oral fluid intake versus delayed intake or standard fasting. Primary outcome was PONV incidence. Secondary outcomes included thirst alleviation, oropharyngeal discomfort, patient satisfaction, time to PACU discharge, and gastrointestinal recovery. Subgroup analyses by fluid volume and timing were considered exploratory. Two reviewers independently screened studies, extracted data, and assessed risk of bias. Random-effects models were used. TSA and GRADE were applied to the primary outcome.

RESULTS: Thirteen studies (11 randomised controlled trials, 2 non-randomised studies) involving 4,528 adults were included. Early oral fluid intake significantly reduced PONV incidence (RR 0.60, 95% CI 0.50 to 0.73; moderate certainty). TSA indicated that the cumulative evidence crossed the trial sequential monitoring boundary, supporting the robustness of this finding. Exploratory subgroup analyses suggested that volumes of 20-49 mL and 100-199 mL were associated with lower PONV. Early oral intake also shortened time to first flatus (MD -3.27 hours; low certainty). Evidence for thirst alleviation, patient satisfaction, oropharyngeal discomfort, and PACU discharge time was of very low certainty owing to substantial heterogeneity and imprecision. No aspiration events were observed, although trials were not powered to exclude rare adverse events.

CONCLUSIONS: PACU-initiated early oral fluid intake appears feasible and was associated with reduced PONV in appropriately selected adults after general anaesthesia. Evidence for secondary outcomes remains limited by heterogeneity and risk of bias. Larger, standardized trials are needed to define optimal timing and volume and to strengthen evidence for patient-reported and recovery outcomes.