Perineural Methylene Blue Infusion in Lower Limb Amputation Surgery

Study Overview
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Brief Summary
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This prospective randomized controlled study will be conducted to evaluate the analgesic effect of continuous perineural infusion of methylene blue with bupivacaine on acute postoperative pain and to evaluate its preventive role against chronic phantom pain in patients undergoing lower limb amputation surgery

Detailed Description
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Post amputation pain remains an extremely challenging pain condition to treat, so the prevention of phantom pain is our goal to decrease its incidence. Methylene blue, an inhibitor of nitric oxide synthase and guanylate cyclase, has been widely applied for a variety of pain-related diseases due to its characteristic abilities, such as the blocking of pain transmission, antioxidant, and anti-inflammatory effects. Methylene blue can maintain local anesthesia for approximately 20 days so it can be used as a nerve block to relieve pain, especially refractory neuropathic pain.

Official Title
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The Preventive Value of Continuous Perineural Methylene Blue Infusion in Patients Undergoing Lower Limb Amputation Surgery

Conditions
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Perineural, Methylene Blue, Lower Limb Amputation

Intervention / Treatment
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* Drug: Bupivacaine methylene blue
* Drug: bupivacaine saline


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients of both genders, suffering from vascular insufficiency of one or both lower limbs and scheduled for above or below knee amputation under general anesthesia. Exclusion Criteria: Patients with a history of allergy to local anesthetics. Patients with allergy to methylene blue. Anticoagulant use or coagulopathy.

Ages Eligible for Study
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Minimum Age: 18 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: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Bupivacaine methylene blue group<br>Patients in this group will receive the following regimen through the perineural catheter: Bolus dose of 1 ml methylene blue 1% (10 mg) plus 19 ml bupivacaine 0.25% will be given intraoperatively before wound closure, and perineural infusion of methylene blue plus bupivacaine 0.25% (1 ml of methylene blue added to each 49 ml of bupivacaine 0.25%) will be started in the recovery room at a rate of 2-5 ml/hour for 72 hours postoperatively | Drug: Bupivacaine methylene blue<br>* Patients in this group will receive the following regimen through the perineural catheter: Bolus dose of 1 ml methylene blue 1% (10 mg) plus 19 ml bupivacaine 0.25% will be given intraoperatively before wound closure, and perineural infusion of methylene blue plus bupivacaine 0.25% (1 ml of methylene blue added to each 49 ml of bupivacaine 0.25%) will be started in the recovery room at a rate of 2-5 ml/hour for 72 hours postoperatively<br>|
| Active Comparator: Bupivacaine saline group<br>Patients in this group will receive the following regimen through the perineural catheter: Bolus dose of 1 ml normal saline plus 19 ml bupivacaine 0.25% will be given intraoperatively before wound closure, and perineural infusion of bupivacaine 0.25% will be started in the recovery room at a rate of 2-5 ml/hour for 72 hours postoperatively | Drug: bupivacaine saline<br>* Patients in this group will receive the following regimen through the perineural catheter: Bolus dose of 1 ml normal saline plus 19 ml bupivacaine 0.25% will be given intraoperatively before wound closure, and perineural infusion of bupivacaine 0.25% will be started in the recovery room at a rate of 2-5 ml/hour for 72 hours postoperatively<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Degree of postoperative pain | Degree of postoperative pain will be assessed using visual analogue scale which is a 10 cm scale ranging from (0 = no pain to 10 = worst possible pain) | 3 days after surgery | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidence of phantom limb pain | Incidence of phantom limb pain at day 6 after surgery then at 1, 3, 6, 9 months after surgery | 9 months after surgery | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Perineural, Methylene blue, Lower limb amputation