Changes in the Microvascular Reactivity on Leg During Spinal Anesthesia

Study Overview
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Brief Summary
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Anesthesia alters microcirculation and tissue oxygen saturation (StO2). We sought to examine changes in StO2 using near-infrared spectroscopy and a vascular occlusion test (VOT) during spinal anesthesia. This prospective observational study was included 51 patients without comorbidities who underwent elective surgery under spinal anesthesia. We measured the StO2 in the lower extremity during VOT before and after intrathecal injection.

Detailed Description
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The vascular occlusion test (VOT) procedure was conducted twice in each patient, before and 15 min after intrathecal injection. An near-infrared spectroscopy (NIRS) sensor (INVOSTM 5100C Cerebral/Somatic Oximeter; Medtronic, Minneapolis, MN, USA) was attached to the patient's gastrocnemius muscle. A tourniquet (A.T.S ® 3000 Automatic Tourniquet System; Zimmer Inc., Warsaw, IL, USA) was applied to the thigh and inflated to a pressure value 50 mmHg over the patient's baseline systolic blood pressure in the leg and maintained for 5 min. After a 5-min ischemic period, the tourniquet was rapidly deflated to 0 mmHg. The tissue oxygen saturation (StO2) data was continuously recorded during the VOT procedure. After confirmation of spinal anesthesia using cold sensitivity, the VOT procedure was repeated in the same manner as mentioned above. The occlusion slope and recovery slope were calculated based on the measured StO2 data. The occlusion slope was defined as the descending slope of StO2 value until it reached the minimum value. The recovery slope was calculated from the deflation of the tourniquet until the recovery of StO2 to the maximum value.

Official Title
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Changes in the Microvascular Reactivity on Leg During Spinal Anesthesia

Conditions
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Spinal Anesthesia

Intervention / Treatment
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* Diagnostic Test: Vascular occlusion test


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: The patients who were scheduled for spinal anesthesia 18< age < 60 years old Exclusion Criteria: American Society of Anesthesiologists physical status class > III, allergy or sensitivity to study medications, alcohol or drug abuse history, body mass index > 35 kg/ m2 or < 15 kg/m2, p regnancy or breastfeeding status, diabetes and on insulin treatment, untreated or uncontrolled arterial hypertension, peripheral arterial disease, corticosteroid treatment, coagulopathy, and lower limb deformities or burns patients who may not tolerate VOT

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Intervention/Treatment |
| --- |
|Diagnostic Test: Vascular occlusion test|The VOT procedure was conducted twice in each patient, before and 15 min after intrathecal injection. An NIRS sensor (INVOSTM 5100C Cerebral/Somatic Oximeter; Medtronic, Minneapolis, MN, USA) was attached to the patient's gastrocnemius muscle. A tourniquet (A.T.S ® 3000 Automatic Tourniquet System; Zimmer Inc., Warsaw, IL, USA) was applied to the thigh and inflated to a pressure value 50 mmHg over the patient's baseline systolic blood pressure in the leg and maintained for 5 min. After a 5-min ischemic period, the tourniquet was rapidly deflated to 0 mmHg. The StO2 data was continuously recorded during the VOT procedure. After confirmation of spinal anesthesia using cold sensitivity, the VOT procedure was repeated in the same manner as mentioned above. The occlusion slope and recovery slope were calculated based on the measured StO2 data.|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change of recovery slope between baseline and after spinal anesthesia | Recovery slope is related to microvascular reactivity, was calculated from the deflation of the tourniquet until the recovery of tissue oxygen saturation to the highest value | baseline and immediately after spinal anesthesia | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Microvascular Circulation, Spectroscopy, near-infrared, Spinal anesthesia