Permitted does not mean consumed: Real-world drinking behaviour after the implementation of a liberal fasting protocol

BACKGROUND: Liberal preoperative fasting protocols permit clear-fluid intake up to 1 h before anaesthesia. Such policies define what patients are allowed to drink rather than what they actually consume. Real-world drinking behaviour under such protocols remains poorly characterised. METHODS: We conducted a descriptive observational study following the implementation of a liberal clear-fluid fasting protocol. Patient-reported timing of the last fluid intake was recorded at induction of anaesthesia at two time points, 4 and 8 months after implementation. In a separate exploratory substudy, drinking behaviour was characterised in 25 patients by serial measurement of fluid consumption over 1 h. RESULTS: At 4 months, 37 of 58 patients (64%) reported drinking within the final hour before anaesthesia. At 8 months, after reinforcement of the protocol and inclusion of black coffee as a permitted clear fluid, 51 of 73 patients (70%) reported drinking within 1 h. In the exploratory substudy, drinking patterns were highly heterogeneous, ranging from immediate consumption to no intake despite availability. CONCLUSION: Removal of traditional fasting barriers does not standardise patient behaviour. Liberal fasting protocols are permissive and actual preoperative fluid intake is often limited. These findings have implications for how permitted intake is interpreted in physiological and protocol implementation contexts.