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NCT Number: NCT07474480

Comparison of the Effects of General Anesthesia and Spinal Anesthesia on Tissue Perfusion in Patients Undergoing Lower Extremity Surgery

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.

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Key information

Conditions

Tissue Perfusion General Anesthesia Lower Extremity Surgery Tourniquet-Induced Ischemia-Reperfusion Injury

Age range

18 year–65 year

Sex eligibility

All sexes

Study type

Observational

Primary location

Cemil Tasciogu Research and Training Hospital

Istanbul, Sisli, Turkey (Türkiye)

Who can participate

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

Primary outcomes

  1. Percentage AUC Loss During Tourniquet Inflation

    Time frame: 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 outcomes

  1. Reperfusion Response Assessed by ΔNIRS

    Time frame: 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.

  2. Early Hyperemia (rSO₂ Overshoot)

    Time frame: Within 5 minutes after tourniquet deflation

    Mean Change in Regional Oxygen Saturation (rSO₂) Above Baseline After Tourniquet Deflation

  3. Association Between Tourniquet Duration and Percentage AUC Loss

    Time frame: Intraoperative period, during tourniquet use

    Correlation between tourniquet duration and percentage AUC loss in distal tissue oxygenation/perfusion.

Other outcomes

  1. Metabolic and Inflammatory Markers

    Time frame: Perioperative period

    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.

Sponsors and collaborators

Lead sponsor

Prof. Dr. Cemil Tascıoglu Education and Research Hospital Organization

Other

Registry information

Official study title

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

Acronym: Perf-LEX

Important dates

Study start
2025
Primary completion
2025
Study completion
2025
First posted
Mar 16, 2026
Registry last updated
May 28, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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