Does Anesthetic Technique Affect Pneumatic Tourniquet Pressures in Upper Limb Fracture Surgery?

Study Overview
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Brief Summary
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In pneumatic tourniquet applications, the use of an individualized, lowest-effective tourniquet pressure (TP) has been recommended, in order to avoid pressure related complications. The aim of this study is to compare the effects of general anesthesia and axillary block on arterial occlusion pressure (AOP) estimation based TP settings in upper limb fracture surgery. After, ethical committee approval 80 adult patients undergoing upper limb fracture surgery who gave their signed informed consent will be included. The age below 18 and above 85 years, American Society of Anesthesiology (ASA) physical status >2, any contraindication to axillary block or GA, adverse reaction history to anesthetic drugs, severe anemia, and refusal to give informed consent will be the exclusion criteria. The patients will be randomized to one of two study groups using a computer-generated randomization list to receive GA (Group 1) and axillary block (Group 2). Main endpoints are initial and maximal blood pressures, AOP, initial and maximal TPs, and tourniquet time. Additionally, the surgeon will evaluate the quality of bloodless surgical area with respect to the amount of blood using a 4-point scale (1: Excellent= No blood in the surgical field, 2: Good= Some blood in the surgical field but no interference with surgery, 3: Fair= Blood in the surgical field but no significant interference with surgery, 4: Poor= Blood in the surgical field obscures the view) at the beginning, in the middle, and at the end of the surgical procedure. The patients will be observed for signs of tourniquet related complications by a blind investigator. SPSS 20.0 for Windows is used for data analysis. The t test and the χ2 test will be used for continuous and categorical data respectively. A P value below 0.05 will be considered as statistically significant.

Official Title
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Does Anesthetic Technique Affect Pneumatic Tourniquet Pressures in Upper Limb Fracture Surgery? A Comparison of General Anesthesia and Axillary Brachial Plexus Block

Conditions
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Initial Systolic Blood Pressure (mmHg), Arterial Occlusion Pressure (mmHg), Tourniquet Time (Minutes), Quality of Bloodless Surgical Field (4 Point Scale), Initial Tourniquet Pressure (mmHg), Maximal Systolic Blood Pressure (mmHg), Maximal Tourniquet Pressure (mmHg)

Intervention / Treatment
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* Procedure: Upper limb fracture surgery and arterial occlusion pressure (AOP) estimation based tourniquet pressure (TP) setting


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adult patients undergoing upper limb fracture surgery Exclusion Criteria: The age below 18 and above 85 years, American Society of Anesthesiology (ASA) physical status >2 Any contraindication to axillary block or general anesthesia Any contraindication to tourniquet use Adverse reaction history to anesthetic drugs Severe anemia Refusal to give informed consent

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 85 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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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Group 1 (General anesthesia group)<br>Upper limb fracture surgery will be performed with the aid of pneumatic tourniquet. General anesthesia will be induced with intravenous (IV) thiopental sodium and fentanyl. Rocuronium will be used as the neuromuscular blocking agent. Endotracheal tube will be placed and anesthesia will be maintained with sevoflurane and IV fentanyl while the lungs were ventilated with O2-N2O (50-50%) to achieve an EtCO2 at 30-35 mm Hg. | Procedure: Upper limb fracture surgery and arterial occlusion pressure (AOP) estimation based tourniquet pressure (TP) setting<br>* Upper limb fracture surgery will be performed with the aid of a pneumatic tourniquet. The cuff (11 cm) of the tourniquet will be placed around the arm with the distal edge 5 cm above the olecranon. AOP estimation formula according to initial systolic blood pressure (SBP) and Tissue Padding Coefficient (KTP) values (AOP= [SBP+10]/KTP) from a list (Table 1) will be used to calculate AOP (17). After calculation of AOP, a safety margin of 20 mmHg will be added to AOP to determine the TP (TP=AOP+20 mm Hg). Exsanguination of the limb will be provided with an Esmarch bandage and the cuff will be inflated to the predetermined TP. TP will be manually raised in response to each 10 mmHg increase in SBP during the surgical procedure.<br>|
| Active Comparator: Group 2 (Multiple injection axillary block group)<br>Multiple injection axillary block will be performed with the aid of a nerve stimulator. When the slight twitching of the motor response from the relevant muscles is achieved (at 0.4 mA, 2Hz, 0.1 ms) % 18-20 ml of Bupivacaine 0.5 (90-100 mg) will be injected. | Procedure: Upper limb fracture surgery and arterial occlusion pressure (AOP) estimation based tourniquet pressure (TP) setting<br>* Upper limb fracture surgery will be performed with the aid of a pneumatic tourniquet. The cuff (11 cm) of the tourniquet will be placed around the arm with the distal edge 5 cm above the olecranon. AOP estimation formula according to initial systolic blood pressure (SBP) and Tissue Padding Coefficient (KTP) values (AOP= [SBP+10]/KTP) from a list (Table 1) will be used to calculate AOP (17). After calculation of AOP, a safety margin of 20 mmHg will be added to AOP to determine the TP (TP=AOP+20 mm Hg). Exsanguination of the limb will be provided with an Esmarch bandage and the cuff will be inflated to the predetermined TP. TP will be manually raised in response to each 10 mmHg increase in SBP during the surgical procedure.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Initial and maximal systolic blood pressure (mmHg) | Initial and maximal systolic blood pressures define the systolic blood pressures measured and recorded by the patient monitor just before tourniquet inflation and during tourniquet application respectively. | Intraoperative | 
| Arterial occlusion pressure (mmHg) | Arterial occlusion pressure is the minimal tourniquet pressure required to cease arterial blood flow to the limb and calculated with AOP estimation formula according to initial SBP and Tissue Padding Coefficient (KTP) values (AOP= [SBP+10]/KTP) from a list. | Intraoperative | 
| Initial and maximal tourniquet pressures (mmHg) | Initial and maximal tourniquet pressures define first adjusted and maximal tourniquet pressures during surgery. | Intraoperative | 
| Tourniquet time (minute) | Tourniquet time defines the time period between the inflation and deflation of the tourniquet cuff at the beginning and end of the surgery respectively. | Intraoperative | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The quality of bloodless surgical area | The quality of bloodless surgical area will be evaluated by the surgeon respect to the amount of blood using a 4-point scale (1: Excellent= No blood in the surgical field, 2: Good= Some blood in the surgical field but no interference with surgery, 3: Fair= Blood in the surgical field but no significant interference with surgery, 4: Poor= Blood in the surgical field obscures the view) at the beginning, in the middle, and at the end of the surgical procedure. | Intraoperative | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Pneumatic tourniquet, Pressure, Upper extremity, General anesthesia, Axillary brachial plexus block.