Bioimpedance spectroscopy fluid analysis in acute high-risk abdominal surgery, a prospective clinician-blinded observational feasibility study

Abstract

Objective assessment of fluid status in critical surgical care may help optimize perioperative fluid administration and prevent postoperative fluid retention. We evaluated the feasibility of hydration status and fluid distribution assessment by Bioimpedance spectroscopy Analysis (BIA) in patients undergoing acute high-risk abdominal (AHA) surgery. This observational study included 73 patients undergoing AHA surgery. During the observational period (0-120 h), we registered BIA calculated absolute fluid overload (AFO) and relative fluid overload (RFO), defined as AFO/extracellular water ratio, as well as cumulative fluid balance and weight. Based on RFO values, hydration status was classified into three categories: dehydrated (RFO < - 10%), normohydrated (- 10% ≤ RFO ≤ + 15%), overhydrated RFO > 15%. We performed a total of 365 BIA measurements. Preoperative overhydration was found in 16% of patients, increasing to 66% by postoperative day five. The changes in BIA measured AFO correlated with the cumulative fluid balance (r2 = 0.44, p < .001), and change in weight (r2 = 0.55, p < .0001). Perioperative overhydration measured with BIA was associated with worse outcome compared to patients with normo- or dehydration. We have demonstrated the feasibility of obtaining perioperative bedside BIA measurements in patients undergoing AHA surgery. BIA measurements correlated with fluid balance, weight changes, and postoperative clinical complications. BIA-assessed fluid status might add helpful information to guide fluid management in patients undergoing AHA surgery.

Keywords: Bioimpedance spectroscopy; Emergency laparotomy; Fluid assessment; Fluid overload.

Fig. 1

Distribution of hydration status by Bioimpedance Spectroscopy Analysis in the early perioperative period: dehydration (RFO <  − 10%), normohydration (− 10% ≤ RFO ≤  + 15%), overhydration RFO > 15%. RFO relative fluid overload

Fig. 2

Relationship between fluid balance, changes in weight, and changes in absolute fluid overload on postoperative day five in acute high-risk abdominal surgery: A Absolute fluid overload and cumulative fluid balance; B Absolute fluid overload and changes in weight; C Cumulative fluid balance and changes in weight

Fig. 3

Associations between pre- to 6 h postoperative changes in volume status and net fluid balance in patients undergoing acute high-risk abdominal surgery. Regression equations are as follows: A Change in intra cellular volume; B Change in extra cellular volume; C Change in total body volume; D Change in intra cellular volume and extra cellular volume. Pearson correlation test. R² = coefficient of determination

Fig. 4

Association between cumulative fluid balance and Bioimpedance Spectroscopy Analysis measured overhydration, *statistically significant (p < .01): Daily fluid balance was defined as the difference between total input (all fluids, nutrition, blood products, medications) and total output (losses through urinary, gastrointestinal, or other drainage tubes), not including insensible losses). Cumulated fluid balance was calculated as the algebraic sum of daily fluid balance during the observational period; overhydration: Relative fluid overload > 15%