GDFT and Postoperative Cognitive Function in Geriatric Cancer Surgery

Postoperative neurocognitive disorders, including early postoperative cognitive decline, represent a significant source of morbidity in geriatric patients undergoing major abdominal cancer surgery. These impairments are multifactorial and are thought to arise from the interaction of perioperative hemodynamic instability, impaired cerebral autoregulation, systemic inflammatory responses, and age-related reductions in physiological reserve.

Among perioperative factors, intraoperative fluid management plays a central role in maintaining adequate tissue perfusion and organ function. Both hypovolemia and fluid overload have been associated with adverse outcomes, including impaired microcirculatory perfusion and potential effects on cerebral oxygen delivery. Traditional fluid management strategies, typically based on fixed formulas and static physiological parameters, may not adequately reflect inter-individual variability, particularly in elderly patients with altered cardiovascular compliance and limited adaptive capacity.

Goal-directed fluid therapy (GDFT) has emerged as an individualized hemodynamic management strategy aimed at optimizing stroke volume and tissue perfusion through the use of dynamic indicators of fluid responsiveness. While randomized trials and meta-analyses have demonstrated that GDFT can improve perioperative outcomes such as complication rates and length of hospital stay, its impact on postoperative cognitive outcomes remains insufficiently characterized, especially in oncologic geriatric populations.

Recent advances in non-invasive hemodynamic monitoring technologies, including the use of pleth variability index (PVI) and perfusion index (PI), allow continuous assessment of fluid responsiveness without the need for invasive cardiac output monitoring. These tools offer a practical and safer alternative in routine clinical practice, particularly in elderly patients where invasive monitoring may not always be feasible.

This study is designed as a prospective observational cohort study conducted in geriatric patients undergoing elective major abdominal cancer surgery. Patients are managed according to standard clinical practice, and intraoperative fluid management strategy-either PVI/PI-guided GDFT or conventional fluid therapy-is determined by the attending anesthesiologist. No intervention is assigned by the study protocol, and no modification of routine clinical care is performed.

The primary objective of the study is to evaluate the association between intraoperative fluid management strategy and postoperative cognitive trajectory. Cognitive function is assessed using the Mini-Mental State Examination (MMSE) at three time points: preoperatively (baseline), postoperative day 1, and postoperative day 7. The primary outcome is defined as the change in MMSE scores over time.

To appropriately account for repeated cognitive measurements and potential confounding, longitudinal statistical models will be employed. Specifically, mixed-effects modeling will be used to evaluate the interaction between time and fluid management strategy, while adjusting for clinically relevant covariates, including age, ASA physical status, duration of surgery, and intraoperative blood loss.

Secondary objectives include evaluating the association between fluid management strategy and intraoperative physiological parameters, including total fluid administered, mean arterial pressure, heart rate, estimated blood loss, and net fluid balance.

Given the observational nature of the study, results will be interpreted as associations rather than causal effects. The study aims to generate clinically relevant evidence regarding whether individualized, non-invasive, goal-directed fluid strategies are associated with improved early postoperative cognitive recovery and optimized perioperative physiological stability in geriatric surgical patients.

Inclusion criteria

• Age ≥ 65 years (geriatric patients)
• Scheduled for elective major abdominal cancer surgery
• American Society of Anesthesiologists (ASA) Physical Status I-IV
• Eastern Cooperative Oncology Group (ECOG/WHO/Zubrod) performance status ≥ 2
• Ability to complete cognitive assessments
• Provision of written informed consent

Exclusion criteria

• Severe cardiac dysfunction (Cardiac Index ≤ 2.2 L/min/m²)
• History of neurological or psychiatric disorders (e.g., dementia, Alzheimer's disease)
• Use of medications that significantly affect cognitive function
• Severe hepatic or renal failure
• Prior chemotherapy or radiotherapy before surgery
• Intraoperative or perioperative blood transfusion
• Prolonged mechanical ventilation (inability to extubate immediately after surgery)
• Pre-existing cognitive impairment (baseline Mini-Mental State Examination [MMSE] score < 24)