Preoperative Oral Rehydration Solution Intake Volume Does Not Affect Relative Change of Mean Arterial Blood Pressure and Crystalloid Redistribution During General Anesthesia in Low-risk Patients: an Observational Cohort Study

Despite the implementation of liberal preoperative fasting routines, it is unclear whether preoperative oral rehydration solution intake volume affects blood pressure during general anesthesia. We enrolled 60 patients (American Society of Anesthesiologists status I/II) undergoing tympanoplasty. Patients drank 200-1,000 ml oral rehydration solution until 2-3 h before anesthesia induction. Anesthesia was induced by propofol and maintained with sevoflurane and remifentanil. Coinciding with anesthesia induction, 15 ml/kg Ringer's acetate solution was administered intravenously over 60 min followed by 1 ml/kg Ringer's acetate solution over the next 30 min. Mean arterial blood pressure (MAP) and whole-body bioelectrical resistance for extracellular fluid (R e) during anesthesia were compared between retrospectively classified intake groups of oral rehydration solution. There were no differences in mean MAP during the 30-90 min period relative to baseline [0.67 (0.60-0.74), 0.65 (0.61-0.76), 0.64 (0.60-0.70), P = 0.96] and relative R e at 90 min [0.945 (0.018), 0.944 (0.021), 0.943 (0.021), P = 0.95] between the small (n = 14), intermediate (n = 29), and large (n = 17) intake groups. The intake volume of preoperative oral rehydration solution does not affect the magnitude of hypotension during general anesthesia in low-risk patients undergoing minor surgery.