Ayano Ando, Runa Tokunaga, Takahiro Mihara, Makoto Kaneko
Background/Objectives: Postoperative thirst is a common and distressing symptom among surgical patients; however, standardized management guidelines remain limited. Oral care interventions using cold stimulation (e.g., ice chips, popsicles, and menthol-infused products) may relieve postoperative thirst, but variation in intervention protocols and outcome measures has so far precluded clear clinical recommendations. This protocol outlines a systematic review evaluating the effectiveness of cold-stimulation oral care interventions in reducing thirst intensity among adult surgical patients during the immediate postoperative period, defined as the first 6 h after emergence from general anesthesia. Methods: Randomized controlled trials (RCTs) comparing cold-stimulation oral care with standard care will be included; as pre-specified at registration, quasi-randomized trials will be considered only if fewer than three eligible RCTs are identified (appraised with ROBINS-I and reported separately). MEDLINE, Cochrane Library, EMBASE, CINAHL Plus and trial registries were searched. Risk of bias will be assessed using the Cochrane Risk of Bias tool version 2.0. The primary outcome is change in thirst intensity; secondary outcomes are oral dryness, patient satisfaction, and adverse events. Continuous outcomes will be pooled as mean differences, or as standardized mean differences across differing scales, and dichotomous outcomes as risk ratios, with 95% confidence intervals. Random-effects meta-analysis will be performed in R where appropriate, otherwise narrative synthesis, with pre-specified subgroup and sensitivity analyses. Certainty of evidence will be rated using GRADE. Conclusions: This protocol was developed in accordance with PRISMA-P and prospectively registered in PROSPERO (CRD420251139881). The review will clarify the effectiveness and safety of cold-stimulation oral care for postoperative thirst and support perioperative nursing practice.