Changes in Tissue Microcirculation During Ischemic Conditioning: Pilot Study

Study Overview
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Brief Summary
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Changes in tissue microcirculation during ischemic conditioning (4 cycles of 5-min ischemia and 5-min reperfusion) has not been well documented. In previous studies, there was difference in changes in microcirculation, such as recovery slope and occlusion slope, between healthy subjects and cardiac surgery patients. Moreover, the occlusion slope, which reflects local tissue oxygen consumption during ischemic period, is anticipated to decrease during repeated ischemia-reperfusion cycle by its protecting effect, however there has not been well-conducted study. The purpose of the study is to evaluate the changes in microcirculation measured by tissue oxygen saturation during ischemic conditioning between healthy volunteers and cardiac surgery patients.

Detailed Description
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Subjects who are male healthy volunteers (aged 20-45) or who are scheduled to receive cardiac surgery (aged 20-80) will undergo ischemic conditioning, consisting of 4 cycles of 5-min ischemia with pressure of 200 mmHg on upper extremity followed by 5-min reperfusion with no pressure. During ischemic conditioning, changes in tissue microcirculation (baseline tissue saturation, occlusion slope during ischemia, and recovery slope during reperfusion) will be observed using tissue oxygen saturation sensor attached to the thenar muscle of the hand. For cardiac surgery patients, the study will be conducted before anesthesia induction on the surgery day to exclude any potential effect of anesthetics.

Official Title
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Changes in Tissue Microcirculation During Ischemic Conditioning: Pilot Study

Conditions
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Microcirculation

Intervention / Treatment
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* Procedure: ischemic conditioning


Participation Criteria
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Eligibility Criteria
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<Healthy volunteers> Inclusion Criteria: Age 20-45 No underlying chronic disease Male volunteer Exclusion Criteria: Under taking prescription drugs Taking herbal medicines within 2 weeks Baseline systolic blood pressure > 150 mmHg or diastolic pressure > 100 mmHg Body mass index < 18 kg/m^2 or > 30 kg/m^2 Vigorous exercise, excessive alcohol, smoking or caffeine within 24 hours Any abnormalities on upper extremities Do not consent to participate <Cardiac surgery patients> Inclusion Criteria: Age 20-80 Scheduled for cardiac surgery Exclusion Criteria: Baseline systolic blood pressure > 150 mmHg or diastolic pressure > 100 mmHg Body mass index < 18 kg/m^2 or > 30 kg/m^2 Uncontrolled diabetes Under taking beta-blockers Severe renal dysfunction, chronic kidney disease, on hemodialysis Any abnormalities on upper extremities (i.e, AV fistula on arms) Peripheral vascular disease, peripheral neuropathy, coagulopathy Vigorous exercise, excessive alcohol, smoking or caffeine within 24 hours Pregnant Emergency surgery Do not consent to participate

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Diagnostic
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Healthy volunteers<br>Healthy male volunteers will receive ischemic conditioning (4 cycles of 5-min ischemia followed by 5-min reperfusion on upper extremity) while measuring changes in tissue microcirculation at the thenar muscle. | Procedure: ischemic conditioning<br>* Four cycles of 5-min inflation of pneumatic cuff on upper extremity up to 200 mmHg, followed by 5-min deflation with no pressure.<br>|
| Active Comparator: Cardiac surgery patients<br>Patients scheduled for cardiac surgery will receive ischemic conditioning (4 cycles of 5-min ischemia followed by 5-min reperfusion on upper extremity) while measuring changes in tissue microcirculation at the thenar muscle. | Procedure: ischemic conditioning<br>* Four cycles of 5-min inflation of pneumatic cuff on upper extremity up to 200 mmHg, followed by 5-min deflation with no pressure.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in microcirculation during ischemic conditioning | Changes in occlusion slope during ischemia and recovery slope during reperfusion | During 4-cycles of 5-min ischemia followed by 5-min reperfusion | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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tissue oxygen saturation, ischemic conditioning