Adductor Canal Blocks With Bupivacaine and Magnesium After Same-day Discharge Total Knee Arthroplasty Improve Post-operative Pain Relief and Decrease Opioid Consumption: a Prospective Randomized Controlled Trial

Study Overview
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Brief Summary
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The purpose of this study is to determine whether the addition of magnesium to bupivacaine for the post-operative adductor canal blocks (ACB) can decrease opioid consumption and improve pain management for patients after same-day discharge total knee arthroplasty (TKA). The investigators will assess whether the addition of magnesium will decrease visual analog scale (VAS) pain scores, decrease post-operative total opioid consumption (oral morphine equivalents), decrease the incidence of post-operative nausea and vomiting (PONV), and improve patient satisfaction in comparison to when magnesium is not administered.

Detailed Description
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Total knee arthroplasty (TKA) is one of the most common elective surgical procedures in the United States . The number of TKA procedures has doubled in each of the past two decades and is expected to top 3.4 million per year in the United States by 2030. Within the last 10-15 years significant changes have taken place in the anesthetic management of patients undergoing total knee arthroplasty (TKA). In the past, the majority of patients underwent general anesthesia and were managed post-operatively with a PCA (patient controlled analgesia) pump. More recently anesthesiologists have begun to use neuraxial anesthesia (spinal anesthesia) combined with regional anesthesia (peripheral nerve block (PNB)) techniques combined with monitored anesthesia care (MAC) for many of these surgeries. Regional anesthesia is used to block the sensation in a specific part of body during and after surgery. It offers numerous advantages over conventional general anesthesia, including faster recovery time, fewer side effects, no need for an airway device during surgery, and a dramatic reduction in post-surgical pain and reduction in opioid use following surgery. The use of local anesthetic peripheral nerve blocks for surgical anesthesia and postoperative pain management has increased significantly with the advent of ultrasound-guided techniques. However, the duration of traditional amide-based and ester-based regional anesthesia is normally limited to only a few hours. Techniques including continuous catheter placement or serial injections can be used to enhance the duration and effect of regional anesthesia for postoperative pain control. But these approaches can increase the risk of infection, toxicity, and cost. Therefore, alternative methods of extending the clinical duration of nerve blocks have been a topic of significant interest. Magnesium sulfate, an NMDA receptor antagonist, exerts it analgesic effects by at least two mechanisms: it acts as a physiological calcium antagonist by blocking NMDA receptors and it inhibits the inflammatory response through the reduction of inflammatory cytokines. Magnesium has also been shown to decrease peripheral nerve excitability. Addition of magnesium to intravenous regional anesthesia for chronic limb pain management has demonstrated improvement in quality of blockade and prolonged the duration of analgesia. Magnesium decreased intraoperative opioid consumption and tourniquet pain. Magnesium improved the quality of anesthesia and prolonged the time for first postoperative analgesic requirement. Overall, the addition of magnesium to local anesthetic is effective both for perineural (nerve blocks) and intravenous regional anesthesia. In a recent meta-analysis of randomized controlled trials, Li et al. evaluated seven trials involving 493 patients. Investigators concluded that the addition of magnesium as an adjuvant to PNB prolonged the postoperative duration time of analgesia, sensory, and motor block. Studies have consistently shown that addition of magnesium to local anesthetic significantly prolongs peripheral nerve blocks, including femoral nerve blocks with bupivacaine, interscalene blocks with bupivacaine, and axillary blocks with prilocaine and levobupivacaine. All of these papers denied adjuvant-related toxicity or side effects; however, nausea was two to three times more likely in the first 12 hours after interscalene blocks with 200mg magnesium in the study by Lee et al. This side effect was not reported in studies using 150mg magnesium. The purpose of this study is to determine whether the addition of magnesium to bupivacaine for the post-operative adductor canal blocks can decrease opioid consumption and improve pain management for patients after total knee arthroplasty (TKA). The investigators will assess whether the addition of magnesium will decrease visual analog scale (VAS) pain scores, decrease post-operative total opioid consumption (oral morphine equivalents), decrease the incidence of post-operative nausea and vomiting (PONV), and improve patient satisfaction in comparison to when magnesium is not administered.

Official Title
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Adductor Canal Blocks With Bupivacaine and Magnesium After Same-day Discharge Total Knee Arthroplasty Improve Post-operative Pain Relief and Decrease Opioid Consumption: a Prospective Randomized Controlled Trial

Conditions
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Post-operative Pain, Acute

Intervention / Treatment
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* Drug: Adding Magnesium as an adjuvant to the adductor canal Block (ACB) for same-day discharge total knee arthroplasty


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: - Patients undergoing unilateral primary total knee arthroplasty with spinal anesthetic and MAC followed by a unilateral adductor canal block with ultrasound guidance. Exclusion Criteria: Patients on chronic anticoagulation upon admission Patients with significant genetic or acquired clotting/bleeding disorders (hemophilia, DIC, etc.) or significant platelet dysfunction Patients with prior back surgery or leg surgery that precludes spinal or regional anesthesia Infection at sites for regional/spinal anesthesia Allergy to local anesthetics

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 100 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: Supportive Care
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| No Intervention: No_Mg<br>Ctrl Group. Post-operatively all patients will have an ultrasound-guided adductor canal block (ACB) with 30cc of 0.25% bupivacaine. Patients in this Arm (selected randomly) will not receive Mg (the intervention) in the block; instead they will receive 0.3mL of sterile saline. | |
| Experimental: Mg<br>Treatment Group. Post-operatively all patients will have an ultrasound-guided adductor canal block (ACB) with 30cc of 0.25% bupivacaine. Patients in this Arm (selected randomly) will receive 150 mg Mg (0.3 mL-the intervention) in the block. | Drug: Adding Magnesium as an adjuvant to the adductor canal Block (ACB) for same-day discharge total knee arthroplasty<br>* Post-operatively all patients will have an ultrasound-guided adductor canal block (ACB) with 30cc of 0.25% bupivacaine. Half of the patients (selected randomly using random number table) will receive 150mg of magnesium sulfate (0.3mL) in the block and the other half will receive 0.3 mL of saline in the block.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Total opioid consumption (oral morphine equivalents) in the first 24 hours after surgery | Measuring the post surgical total opioid consumption in the first 24 hours after surgery by calculating oral morphine equivalents (mg) | The first 24 hours after surgery | 
| Total opioid consumption (oral morphine equivalents) in the second 24 hours after surgery | Measuring the post surgical total opioid consumption in the second 24 hours after surgery by calculating oral morphine equivalents (mg) | The second 24 hours after surgery | 
| Visual analog scale (VAS) pain score at 24 hours after surgery | Determining pain scores using Visual analog scale (VAS) at 24 hours after surgery (0-10, Higher scores mean worse outcome) | 24 hours after surgery | 
| Visual analog scale (VAS) pain score at 48 hours after surgery | Determining pain scores using Visual analog scale (VAS) at 48 hours after surgery (0-10, Higher scores mean worse outcome) | 48 hours after surgery | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Percentage of incidence of post-operative nausea/ vomiting in first 48 hours after surgery | The incidence of nausea or vomiting in the first 48 hours after surgery is recorded | First 48 hours after surgery | 
| Overall patient satisfaction in first 48 hours after surgery | Patient satisfaction scores averaged over the first 48 hours after surgery (0-10, higher scores are better) | First 48 hours after surgery | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Same-day discharge total knee arthroplasty; Magnesium; Adductor canal block; Post-operative opioid consumption; Post-operative pain management