General Anesthesia, Lower Extremity Surgery, Tissue Perfusion, Tourniquet-Induced Ischemia-Reperfusion Injury
Conditions
Brief summary
This prospective, single-center observational study compares the effects of general anesthesia and spinal anesthesia on tissue perfusion in patients undergoing lower extremity surgery with tourniquet use. Tissue oxygenation in the limb distal to the tourniquet is monitored noninvasively using near-infrared spectroscopy (NIRS), and perfusion loss is quantified using an area-under-the-curve (AUC) approach. The primary objective is to evaluate whether spinal anesthesia better preserves distal tissue oxygenation during tourniquet inflation compared with general anesthesia. Secondary objectives are to assess reperfusion response after tourniquet release using changes in NIRS values at 20 minutes relative to baseline, the presence of early hyperemia (rSO₂ overshoot), and the association between tourniquet duration and perfusion loss. Additional exploratory analyses evaluate selected metabolic and inflammatory markers, including pH, lactate, and potassium.
Interventions
None listed
Sponsors
Prof. Dr. Cemil Tascıoglu Education and Research Hospital Organization
Study design
Observational model
COHORT
Time perspective
PROSPECTIVE
Eligibility
Sex/Gender
ALL
Age
18 Years to 65 Years
Inclusion criteria
* Age 18 to 65 years * Scheduled for elective lower extremity orthopedic surgery * ASA physical status I or II * Expected operation duration 30 to 120 minutes * Expected tourniquet duration 30 to 90 minutes * Informed about the anesthesia method and agreed to participate voluntarily * No contraindication to neuraxial block
Exclusion criteria
* Refusal to participate * History of peripheral arterial disease, diabetic neuropathy, or advanced vascular insufficiency * Severe or uncontrolled systemic disease, including ASA III or higher * Coagulopathy, local infection, or contraindication to spinal anesthesia * Body mass index greater than 35 kg/m² * Pregnancy or impaired consciousness * Intraoperative hemodynamic instability or anticipated instability * Need for additional intraoperative sedative or analgesic medication * Inability to obtain adequate and reliable NIRS signal for technical reasons
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Percentage AUC Loss During Tourniquet Inflation | From tourniquet inflation to tourniquet deflation during surgery | Distal tissue oxygenation/perfusion loss measured by near-infrared spectroscopy (NIRS) as the percentage area-under-the-curve (AUC) loss of regional tissue oxygen saturation (rSO₂) during tourniquet inflation. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Reperfusion Response Assessed by ΔNIRS | Baseline to 20 minutes after tourniquet deflation | Change in distal regional tissue oxygen saturation (rSO₂) measured by NIRS, defined as the 20th minute after tourniquet deflation minus baseline value. |
| Early Hyperemia (rSO₂ Overshoot) | Within 5 minutes after tourniquet deflation | Mean Change in Regional Oxygen Saturation (rSO₂) Above Baseline After Tourniquet Deflation |
| Association Between Tourniquet Duration and Percentage AUC Loss | Intraoperative period, during tourniquet use | Correlation between tourniquet duration and percentage AUC loss in distal tissue oxygenation/perfusion. |
Countries
Turkey (Türkiye)
Outcome results
None listed