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.

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 <90 mmHg or >180 mmHg, or heart rate <50 or >120 beats/min
• Missing study data or inability to obtain records in accordance with the study protocol