An interventional study of Ionolyte Balanced Isotonic Crystalloid in Postoperative Complications, sponsored by University Hospital of Split. Not yet recruiting at 1 site in Croatia. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-09-16.
Sponsored by University Hospital of Split · Not applicable, Interventional, and Basic science
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.
The prospective component is protocol-assigned, non-randomized, open-label, and single-group. 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. An eGFR of at least 60 mL/min/1.73 m² is an eligibility criterion and is not used to calculate fluid volume.
From infusion start through T60, food, drink, and other intravenous fluids are withheld unless clinically required. Routine walking to the toilet and standing scale is permitted. Only T0 and T60 research BIA measurements are performed. Clinical care takes priority over the protocol, and symptoms or clinician concern require stopping the infusion and performing a medical assessment.
Short-term outcomes are assessed through 90 postoperative days. Long-term outcomes include overall survival and, in participants with malignant disease, recurrence-free survival for up to five years.
The complete ambispective research program also includes 240 consecutive eligible patients operated on immediately before implementation of the prospective protocol. Their data are obtained retrospectively from existing University Hospital of Split records without contact or additional procedures, under the approved waiver of consent. This historical comparison is not a prospectively assigned ClinicalTrials.gov arm and is not included in the anticipated enrollment of 120.
Exclusion Criteria:
Prospective participants undergo standardized BIA and weighing at T0 after bladder emptying, protocol-defined Ionolyte infusion over exactly 40 minutes, repeat bladder emptying, and BIA and weighing at T60, followed by usual elective colon or rectal resection and outcome follow-up.
Drug: Ionolyte Balanced Isotonic Crystalloid
Ionolyte 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.
Also known as: Balanced Isotonic Crystalloid
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.
Time frame: From surgery through postoperative day 30
Change in Phase Angle
Whole-body/software-reported phase angle at T60 minus T0, analyzed continuously.
Time frame: T0 to 60 minutes after infusion start
Change in Extracellular Water
Extracellular water at T60 minus extracellular water at T0, measured in kilograms and analyzed continuously.
Time frame: T0 to 60 minutes after infusion start
Major Postoperative Complications
Participants with at least one Clavien-Dindo grade III-V complication.
Time frame: Through postoperative day 30
Comprehensive Complication Index
Cumulative postoperative morbidity on the 0-100 CCI scale; higher scores indicate greater morbidity.
Time frame: Through postoperative day 30
Surgical-Site Infection
Participants meeting the protocol-defined surgical-site infection criteria.
Time frame: Through postoperative day 30
Anastomotic Leakage
Participants with clinically and/or radiologically diagnosed anastomotic leakage according to the protocol definition.
Time frame: Through postoperative day 30
Number of Participants With Acute Kidney Injury
Participants meeting KDIGO acute kidney injury criteria based on available creatinine and/or valid routine urine-output data.
Time frame: From surgery through postoperative day 30
Length of Hospital Stay
Number of days from the colon or rectal resection to discharge from the hospitalization during which the resection was performed.
Time frame: From colon or rectal resection through discharge from the hospitalization during which the resection was performed, up to 90 days after surgery
Number of Participants With an Unplanned Reoperation
Participants undergoing an unplanned reoperation.
Time frame: Through postoperative day 30
Number of Participants With Hospital Readmission
Participants readmitted after discharge.
Time frame: Through postoperative day 30
All-Cause Mortality
All-cause mortality reported separately at 30 and 90 days.
Time frame: Postoperative days 30 and 90
Overall Survival
Time from surgery to death from any cause; living participants are censored at last known follow-up.
Time frame: Up to 5 years after surgery
Recurrence-Free Survival
For malignant disease with available follow-up, time from surgery to documented recurrence or death according to the statistical analysis plan definition.
Time frame: Up to 5 years after surgery
Change in Intracellular Water
Intracellular water at T60 minus intracellular water at T0, measured in kilograms and analyzed continuously.
Time frame: T0 to 60 minutes after infusion start
Change in Total Body Water
Total body water at T60 minus total body water at T0, measured in kilograms and analyzed continuously.
Time frame: T0 to 60 minutes after infusion start
Change in Extracellular Water to Total Body Water Ratio
The device-reported ECW/TBW ratio at T60 minus the ratio at T0, analyzed continuously.
Time frame: T0 to 60 minutes after infusion start
Change in Whole-Body Resistance at 50 kHz
Whole-body resistance at 50 kHz at T60 minus resistance at T0, measured in ohms and analyzed continuously.
Time frame: T0 to 60 minutes after infusion start
Change in Whole-Body Reactance at 50 kHz
Whole-body reactance at 50 kHz at T60 minus reactance at T0, measured in ohms and analyzed continuously.
Time frame: T0 to 60 minutes after infusion start
Change in Body Weight
Body weight at T60 minus body weight at T0, measured in kilograms and analyzed continuously.
Time frame: T0 to 60 minutes after infusion start
Plan to share: No — Individual participant data will not be made publicly available. The protocol, statistical analysis plan, data-management description, and aggregate results will be shared. Any future controlled sharing would require separate institutional and ethical approval.
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University Hospital of Split