Bioelectrical Response to Preoperative Hydration in Colorectal Surgery (BIA-HYD-CRC)

Bioelectrical Response to Standardized Preoperative Hydration and Its Association With Short- and Long-Term Outcomes After Elective Colon and Rectal Resections: An Ambispective Controlled Cohort Study

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.

Study Overview

• Status: Not yet recruiting
• Conditions: Postoperative Complications
• Intervention / Treatment: Drug: Ionolyte Balanced Isotonic Crystalloid

Detailed Description

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.

• Study Type: Interventional
• Enrollment (Estimated): 120
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Ognjen Barcot, MD, PhD; Phone Number: +38521556691; Email: ognjen.barcot@kbsplit.hr

Study Locations

• Croatia
  • Split-Dalmatia County
    • Split, Split-Dalmatia County, Croatia, 21000
      • University Hospital of Split, Department of Surgery
      • Contact: Petra Nizeteo, MD; Phone Number: +38521551457; Email: petra.nizeteo@kbsplit.hr

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• 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
• Preoperative eGFR at least 60 mL/min/1.73 m²
• Clinically eligible for the protocol fluid volume

Exclusion Criteria:

• 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
• Active implantable electrical device
• Limb amputation, inability to undergo standardized standing BIA, or unsafe standing
• Clinically significant electrolyte abnormality
• Pregnancy
• Contraindication to Ionolyte or any clinician safety concern
• Inability to provide valid informed consent

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: Standardized Ionolyte Hydration and Serial BIA; 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.; Other Names: Balanced Isotonic Crystalloid

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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.	From surgery through postoperative day 30

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Phase Angle	Whole-body/software-reported phase angle at T60 minus T0, analyzed continuously.	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.	T0 to 60 minutes after infusion start
Major Postoperative Complications	Participants with at least one Clavien-Dindo grade III-V complication.	Through postoperative day 30
Comprehensive Complication Index	Cumulative postoperative morbidity on the 0-100 CCI scale; higher scores indicate greater morbidity.	Through postoperative day 30
Surgical-Site Infection	Participants meeting the protocol-defined surgical-site infection criteria.	Through postoperative day 30
Anastomotic Leakage	Participants with clinically and/or radiologically diagnosed anastomotic leakage according to the protocol definition.	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.	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.	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.	Through postoperative day 30
Number of Participants With Hospital Readmission	Participants readmitted after discharge.	Through postoperative day 30
All-Cause Mortality	All-cause mortality reported separately at 30 and 90 days.	Postoperative days 30 and 90
Overall Survival	Time from surgery to death from any cause; living participants are censored at last known follow-up.	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.	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.	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.	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.	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.	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.	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.	T0 to 60 minutes after infusion start

Collaborators and Investigators

• Sponsor: University Hospital of Split
• Investigators: Principal Investigator: Petra Nizeteo, MD, University Hospital of Split

Study record dates

Study Major Dates

• Study Start (Estimated): October 1, 2026
• Primary Completion (Estimated): October 30, 2028
• Study Completion (Estimated): September 30, 2033

Study Registration Dates

• First Submitted: September 8, 2026
• First Submitted That Met QC Criteria: September 12, 2026
• First Posted (Actual): September 16, 2026

Study Record Updates

• Last Update Posted (Actual): September 16, 2026
• Last Update Submitted That Met QC Criteria: September 12, 2026
• Last Verified: September 1, 2026

More Information

Terms related to this study

• Keywords: Body Composition; Colorectal Surgery; Bioelectrical Impedance Analysis; Phase Angle; Clavien-Dindo Classification; Extracellular Water; Intracellular Water; Preoperative Hydration; Balanced Isotonic Crystalloid; Perioperative Fluid Therapy
• Additional Relevant MeSH Terms: Pathologic Processes; Pathological Conditions, Signs and Symptoms; Postoperative Complications
• Other Study ID Numbers: BIA-HYDRATE-CRC; 2181-147/01-06/LJ.Z.-26-02 (Other Identifier: Ethics Committee, University Hospital of Split); 2181-147/01-06/LJ.Z.-26-04 (Other Identifier: Ethics Committee, University Hospital of Split)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: 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.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No