Diastolic Shock Index for Predicting Postspinal Hypotension

This prospective observational study aims to evaluate the diagnostic performance of the preoperative Diastolic Shock Index in predicting postspinal hypotension and to compare its performance with other shock indices, including the Shock Index, Modified Shock Index, and Age Shock Index. The study will include patients aged 50 years and older undergoing elective unilateral inguinal hernia surgery under spinal anesthesia. Hemodynamic parameters will be recorded before and after spinal anesthesia as part of routine clinical monitoring. The primary outcome is the development of postspinal hypotension. Secondary outcomes include vasopressor requirement, total ephedrine dose, lowest intraoperative mean arterial pressure, and the diagnostic performance of the evaluated shock indices using receiver operating characteristic curve analysis. No additional intervention beyond routine anesthetic and perioperative care will be performed for study purposes.

Inclusion Criteria: * Age 50 years or older * Scheduled for elective unilateral inguinal hernia surgery * Scheduled to undergo surgery under spinal anesthesia * American Society of Anesthesiologists physical status I-III * Provision of written informed consent Exclusion Criteria: * Refusal to participate in the study * Emergency surgery * Bilateral inguinal hernia surgery * Contraindication to spinal anesthesia * Failure of spinal anesthesia or conversion to general anesthesia due to failed spinal block * Requirement for additional general anesthesia or deep sedation during surgery * Operation duration exceeding 120 minutes * Atrial fibrillation, atrial flutter, frequent ventricular ectopy, or other arrhythmias preventing reliable heart rate assessment * Presence of a permanent cardiac pacemaker * Severe valvular heart disease * New York Heart Association class III-IV heart failure * Preoperative use of vasopressor or inotropic therapy * Severe hepatic failure or end-stage renal disease * Neurological disease that may significantly affect autonomic nervous system function * Preoperative hemodynamic instability, defined as systolic arterial pressure \180 mmHg, or heart rate \120 beats/min * Missing study data or inability to obtain records in accordance with the study protocol