The investigators propose a multicenter randomized trial to test the renal safety of 6% hydroxyethyl starch (HES) 130/0.4 combined with sodium acetate Ringer's crystalloid solution in moderate-to-high cardiovascular risk patients having major abdominal surgery. The reference group will only be given sodium acetate Ringer's crystalloid.

The investigators propose a multicenter randomized trial to test the renal safety of 6% hydroxyethyl starch (HES) 130/0.4 combined with sodium acetate Ringer's crystalloid solution in moderate-to-high cardiovascular risk patients having major abdominal surgery. The reference group will only be given sodium acetate Ringer's crystalloid.

The investigators will test the primary hypothesis that the maximum decrease in serum Cystatin-C-based estimated glomerular filtration rate (eGFR) from preoperatively through the initial 3 postoperative hospital days is non-inferior in patients who are randomized to a goal-directed combination of HES and crystalloid volume replacement versus goal-directed crystalloid alone.

Secondarily, the investigators will determine the long-term renal safety (cystatin C-based eGFR on postoperative 1 and 3 months) of HES and its effect on major adverse cardiovascular events and the length of hospitalization. Exploratory outcomes will include intraoperative hemodynamic indices, postoperative gastrointestinal indicators, the rate of unscheduled transferring to intensive care unit, the incidence of hospital re-admission within 30 days, the incidence of renal replacement therapy within 90 days after surgery, and the incidence of acute kidney injury based on serum creatine within 7 days.

Inclusion Criteria:

• Are at least 45 years old;

• Scheduled for elective open or laparoscopic gastrointestinal surgery expected to last ≥2 hours;

• Having general anesthesia;

• Expected to require at least overnight hospitalization;

• Subject to at least one of the following risk factors:

  1. Age ≥65 years;
  2. History of peripheral arterial disease;
  3. History of coronary artery disease;
  4. History of stroke or transient ischemic attack;
  5. Diabetes requiring medication;
  6. Current smoking or 15-pack-year history of smoking tobacco;
  7. Body mass index ≥30 kg/m2;
  8. Preoperative high-sensitivity troponin T ≥14 ng/L or troponin I equivalent, defined as ≥15 ng/L (Abbott assay), 19 ng/L (Siemens assay), or 25% of the 99% percentile for other assays - all within 6 months;
  9. B-type natriuretic protein (BNP) ≥80 ng/L or N-terminal B-type natriuretic protein (NT-ProBNP) ≥200 ng/L within six months.

Exclusion Criteria:

• Participate in conflicting studies;
• Are designated American Society of Anesthesiologists physical status 4;
• Are pregnant and/or breastfeeding;
• Have hypoproteinemia (serum albumin <30 g/L) or were given preoperative intravenous colloids, including albumin;
• Have recent intracranial or cerebral hemorrhage;
• Have preoperative acute kidney injury or chronic renal insufficiency (Serum Creatine ≥140 µmol/L for men, Serum Creatine≥120 µmol/L for women and/or oliguria/anuria) or renal replacement therapy;
• Have severe hepatic impairment (Alanine Transaminase (ALT) and/or Aspartate Aminotransferase (AST) more than two times the upper limit of normal);
• Are in congestive heart failure or have pulmonary edema;
• Are critically ill or septic;
• Have electrolyte disorders such as hypernatremia, hyperchloremia, hyperkalemia, or severe alkalosis;
• Are fluid overloaded or dehydrated;
• Have clinically meaningful coagulation or bleeding disorders;
• Had a solid organ transplant;
• Have a current serious burn injury;
• Have a mental illness that precludes adequate consent or cooperation with the proposed trial;
• Have known hypersensitivity or contraindication to Volulyte 6% or any sodium acetate Ringer solution component.

Individual participant data that underlie the results reported in this article, after deidentification (text, tables, figures, and appendices).

Beginning 9 months and ending 36 months following article publication.

Investigators whose proposed use of the data has been approved by an independent review committee ("learned intermediary") identified for individual participant data meta-analysis.

Specifically, everyone except anesthesia clinicians will be blinded to treatment. Anesthesia clinicians who are not blinded will conduct treatment and record intraoperative conditions. Outcome assessors responsible for postoperative follow-up are blinded to patient randomization; Statistical analysis performed independently by the designated blinded statistician. Emergency unblinding will only be done by an investigator and/or dedicated authorized personnel (e.g., the Pharmacovigilance Department of the Sponsor).