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

May 24, 2026 updated by: Taylan Kırdan, Prof. Dr. Cemil Tascıoglu Education and Research Hospital Organization

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

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
60

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

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

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

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

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
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

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
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.
From tourniquet inflation to tourniquet deflation during surgery

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
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.
Baseline to 20 minutes after tourniquet deflation
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.
Intraoperative period, during tourniquet use
Early Hyperemia (rSO₂ Overshoot)
Time Frame: Within 5 minutes after tourniquet deflation
Mean Change in Regional Oxygen Saturation (rSO₂) Above Baseline After Tourniquet Deflation
Within 5 minutes after tourniquet deflation

Other Outcome Measures

Other Outcome Measures

For clinical trials, a planned measurement described in the protocol that is used to determine the effect of an intervention/treatment on participants. For observational studies, a measurement or observation that is used to describe patterns of diseases or traits, or associations with exposures, risk factors, or treatment. Types of outcome measures include primary outcome measure and secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
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.
Perioperative period

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Prof. Dr. Cemil Tascıoglu Education and Research Hospital Organization

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
March 25, 2025

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
September 12, 2025

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 25, 2025

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
March 11, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 11, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
March 16, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
May 28, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
May 24, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
March 1, 2026

More Information

Terms related to this study

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant 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

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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