Usefulness of Bioelectrical Impedance Analysis as a Guidance of Fluid Management in Critically Ill Patients after Major Abdomen Surgery; a Single Center, Prospective Cohort Study

Purpose: We evaluated the patterns and changes in bioelectrical impedance analysis parameters of patient who underwent abdominal surgery throughout the early period in surgical intensive care unit stay. Materials and Methods: From May 2019 to April 2020, patients admitted to surgical intensive care unit for more than 48 hours after surgery were enrolled. Body composition and volume status of patients were measured prospectively using portable bioelectrical impedance analysis device every morning for three days from the day of intensive care unit admission. Overhydration was defined as the case where the value of extracellular water ratio is above 0.390, and the participants were daily classified into overhydration or normohydration group. Relationship between daily volume status measured by bioelectrical impedance analysis and outcomes was assessed. Results: 107 patients who underwent abdominal surgery and 26 patients who underwent endovascular surgery were reviewed as control group. During the first postoperative 48 hours, most of them showed overhydration status, while the rate of overhydaration was significantly lower in the control group. Overhydration status on day 3 was significant predictors of postoperative morbidities (OR 5.709, 95% CI 2.199~14.819, P<0.001) and in-hospital mortality (OR 4.244, 95% CI 1.398~12.883, P<0.001). Conclusion: Overhydration status by extracellular water ratio on postoperative day 3 needs careful monitoring and appropriate interventions to improve the postoperative morbidities and in-hospital mortality. Bioelectrical impedance analysis could be a simple, easy and useful tool to monitor the volume status of patients who requiring intensive fluid resuscitation after abdominal surgery.