Diastolic Shock Index for Predicting Postspinal Hypotension

This prospective observational study will include patients aged 50 years and older undergoing elective unilateral inguinal hernia surgery under spinal anesthesia. The study aims to evaluate the performance of the preoperative Diastolic Shock Index in predicting postspinal hypotension and to compare it with the Shock Index, Modified Shock Index, and Age Shock Index. Baseline systolic, diastolic, and mean arterial pressures and heart rate will be recorded before spinal anesthesia and used to calculate the four shock indices. Hemodynamic parameters will also be recorded at 5, 10, 15, and 20 minutes after spinal anesthesia as part of routine clinical monitoring, without any additional intervention for research purposes.Postspinal hypotension will be defined as a decrease in systolic arterial pressure of at least 25% from baseline and/or a systolic arterial pressure below 90 mmHg. The primary outcome will be postspinal hypotension, while secondary outcomes will include ephedrine requirement, total ephedrine dose, lowest intraoperative mean arterial pressure, and the diagnostic performance of the evaluated indices. Receiver operating characteristic curve analysis will be used to compare the indices and determine the optimal cut-off value for the Diastolic Shock Index, with a minimum of 85 patients planned for inclusion.