Change in Total Body Water as a Metric for Predicting Need for Outpatient Intravenous Fluids in Postoperative Bariatric Patients

Background Dehydration drives a significant proportion of readmissions following bariatric surgery. Routinely performed body composition testing and total body water (TBW) calculations may present a novel method for diagnosing dehydration for outpatient intervention. We sought to determine if a change in TBW from preoperative baseline could help identify bariatric patients requiring outpatient intravenous fluid (IVF) administration for dehydration. Methods The VUMC Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program database was retroactively queried for all patients undergoing bariatric surgery at an accredited bariatric surgery center from January 1, 2017 to May 31, 2018. Body composition test results presurgery and postsurgery were extracted from the electronic health record. Change in TBW was compared between patients requiring outpatient IVF and those who did not use multivariable logistic regression. Results 583 patients underwent surgery over the study period (388 laparoscopic Roux-en-Y gastric bypass, 195 sleeve). 62 (10.6%) required outpatient fluid administration for dehydration. After multivariable analysis, patients with an increased hospital length of stay at index operation were more likely to require outpatient IVF (odds ratio [OR] 1.65, 95% CI 1.22-2.2). Preexisting diabetes diagnosis was protective (OR 0.35, 95% CI 0.16-0.74). Neither 1-week nor 1-month change in TBW from preoperative baseline was significantly different between patients receiving outpatient IVF and those who did not. Conclusion Increased hospital length of stay predicts patients at risk of postoperative dehydration requiring IVF administration. Body composition testing and TBW were not useful in distinguishing between populations. Further research is needed to examine the efficacy of outpatient IVF in preventing hospital readmissions for dehydration.