Perioperative continuous body weight measurements with load cells under the bed legs in patients undergoing abdominal surgery

Abstract

BACKGROUND Both excessive positive fluid balance and body weight increase after surgery are risk factors for poor postoperative outcomes. The use in clinical practice and the value of perioperative body weight measurements are unclear at present, possibly due to difficulty in measuring body weight in patients lying on the bed and insufficient clinical research. OBJECTIVES To investigate the relationship between intraoperative fluid balance and body weight change and perioperative nightly body weight change pattern throughout the hospital stay with contact-free unconstraint load cells placed under the bed legs. DESIGN Observational and exploratory study. SETTING A single university hospital. PATIENTS Twenty adult patients were undergoing elective abdominal surgery under general anaesthesia. MAIN OUTCOME MEASURES Body weight. RESULTS Immediately after surgery, body weight increased significantly by 2.7 ± 1.3 kg, equivalent to a 5% increase from the preoperative body weight. This increase was not correlated with (P = 0.178) the intraoperative fluid balance and was significantly greater than the intraoperative fluid balance 1.5 ± 0.4 kg (P < 0.001). The body weight returned to the preoperative level on postoperative day (POD)3 and further significantly decreased to 97% of the preoperative body weight at POD6 (P < 0.001). This physiological nocturnal weight loss pattern was maintained throughout hospitalisation except when fluid was infused. Compared with their preoperative status, patients stayed in bed longer with smaller body movements and left the bed less frequently during the daytime until POD3. Conversely, the patients had greater body movements in bed during the night leading to smaller diurnal variation in the body movements in bed after POD4. CONCLUSION Both perioperative fluid balance calculation and body weight measurement may have different but mutually complementary roles in perioperative managements. Postoperative fluid and nutrition management strategies are potentially new directions for treatment through continuous weight monitoring during the perioperative period. Trial registration : UMIN Clinical Trials Registry (UMIN000040164).