This single-center study will evaluate whether short-term changes in bioelectrical impedance measurements after a standardized preoperative intravenous fluid infusion can help predict complications following elective colon or rectal surgery. The prospective group will include 120 consecutive adults. After emptying the bladder, participants will be weighed and assessed barefoot on a standing multifrequency bioelectrical impedance device. They will then receive Ionolyte, a balanced isotonic crystalloid, at 15 mL/kg based on the lower of actual and ideal body weight, up to 1,000 mL, over exactly 40 minutes. Participants will empty the bladder again and undergo repeat measurement 60 minutes after infusion start. The main predictor is the continuous change in phase angle, and the main outcome is at least one Clavien-Dindo grade II-V complication within 30 days. A supportive analysis will compare clinical outcomes with 240 consecutive historical controls using existing hospital records. The historical controls do not receive the study procedure and are not included in the prospective enrollment.
Age 18 years or older
Scheduled for elective colon or rectal resection at University Hospital of Split
Written informed consent before research-specific procedures
Able to stand safely and complete both BIA measurements
Emergency surgery
eGFR below 60 mL/min/1.73 m² or oliguria
Heart failure or clinically significant cardiac disease making fluid loading inappropriate
Edema, pulmonary congestion, or clinically significant ascites
Single group
Ionolyte Balanced Isotonic Crystalloid
DrugIonolyte is administered intravenously at 15 mL/kg dosing weight, up to a maximum of 1,000 mL, over exactly 40 minutes. Dosing weight is the lower of actual body weight measured at T0 and ideal body weight calculated from sex and height using the Robinson equations. The infusion rate in mL/h equals the total volume multiplied by 1.5.
Participants With at Least One Clavien-Dindo Grade II-V Postoperative Complication
Number and proportion of participants experiencing at least one postoperative complication graded II, III, IV, or V according to the Clavien-Dindo classification.
Change in Phase Angle
Whole-body/software-reported phase angle at T60 minus T0, analyzed continuously.
Change in Extracellular Water
Extracellular water at T60 minus extracellular water at T0, measured in kilograms and analyzed continuously.
Major Postoperative Complications
Participants with at least one Clavien-Dindo grade III-V complication.
Comprehensive Complication Index
Cumulative postoperative morbidity on the 0-100 CCI scale; higher scores indicate greater morbidity.
Click on the lead sponsor to view all of their trials.
This trial is not recruiting at the moment. You can still explore other options:
