EASIX Score and Post-Induction Hypotension in Frail Patients Undergoing Non-Cardiac Surgery

Evaluation of the Relationship Between Endothelial Activation and Stress Index (EASIX) and Post-Induction Hypotension in Frail Patients Undergoing Non-Cardiac Surgery: A Prospective Observational Cohort Study

Post-induction hypotension (PIH) is a common and clinically significant hemodynamic complication following general anesthesia induction. Frail patients are particularly vulnerable due to impaired vascular reactivity and endothelial dysfunction. The Endothelial Activation and Stress Index (EASIX), calculated from routine laboratory parameters (LDH, creatinine, and platelet count), may serve as a preoperative biomarker to identify patients at risk for PIH.

This prospective observational cohort study aims to evaluate the association between preoperative EASIX score and the occurrence of post-induction hypotension in frail patients undergoing elective non-cardiac surgery under general anesthesia. A total of 160 patients with a Clinical Frailty Scale (CFS) score of 4 or above will be enrolled. Mean arterial pressure will be measured every 2 minutes for the first 15 minutes after induction. PIH is defined as MAP below 65 mmHg and/or a decrease of 20% or more from baseline.

EASIX is calculated as: LDH (U/L) × Creatinine (mg/dL) / Platelet count (10⁹/L), using routine preoperative laboratory values obtained within 24 hours before surgery.

All patients will receive a standardized anesthesia induction protocol: midazolam 0.05 mg/kg, fentanyl 2 mcg/kg, propofol 2 mg/kg, and rocuronium 0.6 mg/kg intravenously, followed by endotracheal intubation after 2 minutes of mask ventilation. Anesthesia maintenance will consist of 2% sevoflurane and remifentanil 0.2 mcg/kg/min infusion.

The primary outcome is the occurrence of PIH within the first 15 minutes after induction. Secondary outcomes include the diagnostic performance of EASIX (ROC-AUC analysis) and the interaction between frailty severity and EASIX on PIH development. Multivariable logistic regression will be performed adjusting for age, sex, ASA classification, baseline MAP, antihypertensive medication use, fasting duration, and induction agent doses.

Inclusion Criteria:

• Age 18 years or older
• Scheduled for elective non-cardiac surgery under general anesthesia
• Clinical Frailty Scale (CFS) score of 4 or above
• Available routine preoperative laboratory values (LDH, creatinine, platelet count) within 24 hours before surgery

Exclusion Criteria:

• Cardiac surgery
• Emergency surgery
• Preoperative vasopressor infusion
• Severe hematological disease
• Missing laboratory data required for EASIX calculation