Magnesium and Postoperative Pain

Study Overview
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Brief Summary
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With ongoing advancements in healthcare leading to prolonged life expectancy, orthopedic surgeries are increasingly performed in elderly patients. Total knee arthroplasty, in particular, has been increasing with the growing demand for improved mobility and quality of life. Total knee arthroplasty is performed on patients with advanced and painful osteoarthritis of the knees, but it can result in moderate to severe postoperative pain during the recovery period. To relieve anxiety or stress during surgery under regional anesthesia, sedation can be provided. Dexmedetomidine is a sedative-analgesic agent acting as α2-adrenergic receptor agonist, and its analgesic effect has been well established in various procedures or surgeries. Magnesium has been reported to produce important analgesic effects including the suppression of neuropathic pain, potentiation of morphine analgesia, and attenuation of morphine tolerance. Although the exact mechanism is not yet fully understood, the analgesic properties of magnesium are believed to stem from regulation of calcium influx into the cell and antagonism of N-methyl-D-aspartate (NMDA) receptors in the central nervous system. In this study, investigators will evaluate the reducing effect of magnesium on the post-total knee arthroplasty pain in patients sedated with dexmedetomidine under spinal anesthesia.

Official Title
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The Influence of Intraoperative Magnesium Sulfate Administration on Postoperative Pain After Total Knee Arthroplasty in Patients Sedated With Dexmedetomidine Under Spinal Anesthesia: A Randomized-controlled Trial

Conditions
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Arthritis Knee, Magnesium Sulfate, Dexmedetomidine

Intervention / Treatment
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* Drug: Magnesium Sulfate
* Drug: Normal saline


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients who undergo total knee arthroplasty under spinal anesthesia Patients who want to sedation during the surgery American Society of Anesthesiologists physical status classification 1 and 2 Exclusion Criteria: General anesthesia Patients who do not want to sedation during the surgery Patients who do not receive patient controlled analgesia postoperatively Muscular disease Hypermagnesemia Atrioventricular block

Ages Eligible for Study
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Minimum Age: 50 Years
Maximum Age: 75 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: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Placebo Comparator: Saline<br>Patient who received normal saline during the operation | Drug: Normal saline<br>* Normal saline group receives the same volume of normal saline, administered according to the same method as in the magnesium group.<br>|
| Experimental: Magnesium<br>Patient who received magnesium sulfate during the operation | Drug: Magnesium Sulfate<br>* Magnesium group receives magnesium sulfate (50 mg/kg) in 100 mL of normal saline over 15 min during induction of anesthesia, followed by a continuous magnesium sulfate infusion (15 mg/kg/h) until the end of surgery.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Patient controlled analgesia (PCA) | Amounts of PCA consumption | Postoperative 24 hour | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Numerical rating scale | Postoperative pain score | Postoperative 24 hour | 
| Rescue analgesics | Amounts of the analgesics administered to mange the postoperative pain | Postoperative 24 hour | 
| Nausea | Incidence of nausea | Postoperative 24 hour | 
| Vomiting | Incidence of vomiting | Postoperative 24 hour | 
| Antiemetics | Amounts of antiemetics consumption | Postoperative 24 hour |