BIA-Guided vs. Conventional Fluid Resuscitation in ICU Patients

In this study aimed to compare bioelectrical impedance analysis (BIA)-guided fluid resuscitation with conventional fluid management strategies in patients admitted to the intensive care unit (ICU) following major surgery. The primary objective is to evaluate whether BIA-guided fluid therapy reduces 28-day mortality by optimizing fluid balance and preventing volume-related complications. Secondary outcomes include cumulative fluid balance, ICU and hospital length of stay, duration of mechanical ventilation, and need for vasopressor or inotropic support. This study is expected to provide evidence for the clinical utility and applicability of BIA in guiding postoperative fluid therapy in critically ill patients.

Inclusion Criteria: * Undergoing major surgery under general anesthesia(Major surgery defined as: vascular clamping or organ ischemia, intraoperative blood loss \>1000 mL, need for \>10 mcg/min norepinephrine infusion, surgery duration \>4 hours, or requirement for perioperative blood transfusion) * Admission to the intensive care unit (CU) after surgery * Informed consent obtained Exclusion Criteria: * Refusal to participate or failure to provide informed consent * Undergoing laparoscopic or emergency surgery * Severe major organ dysfunction:Acute kidney injury stage 2 or 3 (KDIGO 2012) • Acute or chronic liver failure (ALT \>3x or Child A-C cirrhosis * Conditions preventing accurate BIA measurement: • Limb amputation • Metallic cardiac or joint prostheses • Pacemakers or intracardiac stents * Body mass index \>35 kg/m or \< 18 kg/m * Contraindications to lactated Ringer's solution (e.g. hypercalcemia, increased intracranial pressure)