Comparison of the Effects of General Anesthesia and Spinal Anesthesia on Tissue Perfusion in Patients Undergoing Lower Extremity Surgery (Perf-LEX)

Comparison of the Effects of Anesthesia Techniques on Tissue Perfusion in Patients Undergoing Lower Extremity Surgery With Tourniquet Use

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.

Study Overview

• Status: Completed
• Conditions: General Anesthesia; Tissue Perfusion; Lower Extremity Surgery; Tourniquet-Induced Ischemia-Reperfusion Injury

• Study Type: Observational
• Enrollment (Actual): 60

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Sisli
    • Istanbul, Sisli, Turkey (Türkiye)
      • Cemil Tasciogu Research and Training Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: N/A

• Sampling Method: Non-Probability Sample

Study Population

Adults aged 18 to 65 years with ASA physical status I-II who were scheduled for elective lower extremity orthopedic surgery with tourniquet use at Prof. Dr. Cemil Taşcıoğlu City Hospital between 01 March 2025 and 30 September 2025. Eligible patients were assessed consecutively and enrolled after providing informed consent. Patients were analyzed in 2 observational cohorts according to anesthesia method used in routine clinical practice: general anesthesia and spinal anesthesia.

Description

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

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort
General Anesthesia Group; Patients undergoing lower extremity surgery under general anesthesia.
Spinal Anesthesia Group; Patients undergoing lower extremity surgery under spinal anesthesia.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Percentage AUC Loss During Tourniquet Inflation	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.	From tourniquet inflation to tourniquet deflation during surgery

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Reperfusion Response Assessed by ΔNIRS	Change in distal regional tissue oxygen saturation (rSO₂) measured by NIRS, defined as the 20th minute after tourniquet deflation minus baseline value.	Baseline to 20 minutes after tourniquet deflation
Association Between Tourniquet Duration and Percentage AUC Loss	Correlation between tourniquet duration and percentage AUC loss in distal tissue oxygenation/perfusion.	Intraoperative period, during tourniquet use
Early Hyperemia (rSO₂ Overshoot)	Mean Change in Regional Oxygen Saturation (rSO₂) Above Baseline After Tourniquet Deflation	Within 5 minutes after tourniquet deflation

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Metabolic and Inflammatory Markers	Mean Change in pH, Lactate, K+ Across Perioperative Time Points Description: pH, Lactate, K+ will be measured preoperatively, before tourniquet inflation, and after tourniquet release. Changes from each participant's own preoperative baseline will be compared according to anesthesia method.	Perioperative period

Collaborators and Investigators

• Sponsor: Prof. Dr. Cemil Tascıoglu Education and Research Hospital Organization

Study record dates

Study Major Dates

• Study Start (Actual): March 25, 2025
• Primary Completion (Actual): September 12, 2025
• Study Completion (Actual): December 25, 2025

Study Registration Dates

• First Submitted: March 11, 2026
• First Submitted That Met QC Criteria: March 11, 2026
• First Posted (Actual): March 16, 2026

Study Record Updates

• Last Update Posted (Actual): May 28, 2026
• Last Update Submitted That Met QC Criteria: May 24, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Other Study ID Numbers: TK-LEP-001

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data will not be shared because no formal data-sharing plan was established for this thesis-based observational study, and sharing is limited by institutional and ethics requirements.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No