Dexmedetomidine in Serratus Plane Block for Mastectomy

Study Overview
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Brief Summary
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The serratus plane block (SPB) described by Blanco et al, 2013 is a progression from the work with the Pecs I and II blocks. The serratus muscle is a superficial and easily identified muscle and considered a true landmark to perform thoracic wall blocks because lateral cutaneous branches of the intercostal nerves pierce it in the mid-axillary line. A local anesthetic (LA) is injected under ultrasound (US) guidance either superficial or deep to serratus anterior muscle providing predictable and relatively long-lasting regional anesthesia, which would be suitable for surgical procedures performed on the chest wall. The linear US probe of frequency (6-13 MHz) is placed over the mid-clavicular region in a sagittal plane.The ribs are counted inferiorly and laterally until the fifth rib in the midaxillary line is identified.The latissimus dorsi, teres major, and serratus muscles are identified.

Detailed Description
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Possible regional techniques for breast surgery include selective intercostal nerve blockade, thoracic paravertebral blockade, thoracic epidural, intrapleural, local wound infiltration. Each of these techniques has advantages and disadvantages. In general, local or wound infiltration is safe but limited in terms of duration of action, depending on the local anesthetic (LA) used. More invasive techniques such as selective intercostal nerve blocks and thoracic paravertebral blockade may be complicated by pneumothorax or transient Horner's syndrome These techniques are also may be associated with higher risk of local anesthetic toxicity. Besides the neurological side-effects associated with thoracic epidural and paravertebral blocks such as post-sympathectomy hypotension and bradycardia, total spinal block, paraplegia, epidural hematoma, unpredictable spread, intravascular injection also requires special skill precluding their routine use in the setting of day-case surgery. With the use of ultrasound (US) devices in anesthetic practice, newer regional techniques based on detailed knowledge of innervations of the breast are developed as the pectoral nerve (Pecs) block I and II.The breast innervations briefly include lateral and medial pectoral nerves that arise from the brachial plexus innervating the pectoral muscles.The anterior divisions of the thoracic intercostal nerves from T2 to T6. They give off lateral and anterior branches. The Lateral branches pierce the external intercostalis and the serratus anterior muscles at the mid-axillary line to give off anterior and posterior terminal cutaneous branches. The lateral cutaneous branch of the second intercostal nerve does not divide and it is called the intercostobrachial nerve.The Anterior branches pierce the internal intercostalis muscle, the intercostal membranes, and pectoralis major to supply the breast in its medial aspect.The long thoracic nerve passes on the serratus anterior muscle supplying it. The thoracodorsal nerve innervates the latissimus dorsi muscle.

Official Title
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Comparative Study of Bupivacaine Versus Bupivacaine-Dexmedetomidine in Ultrasound Guided Serratus Plane Block for Patients Undergoing Modified Radical Mastectomy

Conditions
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Postoperative Pain

Intervention / Treatment
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* Drug: Bupivacaine-Dexmedetomidine
* Drug: Bupivacaine
* Drug: General anesthesia


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients of American Society of Anesthesiologists (ASA) grade I - III. Scheduled for unilateral modified radical mastectomy. Exclusion Criteria: Patient with the skin infection in the axilla. Allergy to local anesthetics of the amide type. Patient refusal.

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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Female

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 |
| --- | --- |
| Experimental: Bupivacaine-Dexmedetomidine group<br>After general anesthesia, patients will receive a cocktail of isobaric bupivacaine 2.5 mg/ml plus 5 micrograms (mcg)/ml adrenaline and 1mcg/kg dexmedetomidine in a volume of 0.5 ml/kg injected superficial to serratus muscle between and below latissimus dorsi muscle. | Drug: Bupivacaine-Dexmedetomidine<br>* isobaric bupivacaine 2.5 mg/ml plus 5 micro gram/ml adrenaline and 1 micro gram/kg dexmedetomidine in a volume of 0.5 ml/kg<br>|
| Active Comparator: Bupivacaine group<br>After general anesthesia, patients will receive a cocktail of isobaric bupivacaine 2.5 mg/ml plus 5 micrograms (mcg)/ml adrenaline in a volume of 0.5 ml/kg injected superficial to serratus muscle between and below latissimus dorsi muscle. | Drug: Bupivacaine<br>* isobaric bupivacaine 2.5 mg/ml plus 5 micro gram/ml adrenaline in a volume of 0.5 ml/kg<br>|
| Placebo Comparator: Saline group<br>This group will serve as a control and blinding group and will receive saline infiltration in the same manner. | Drug: General anesthesia<br>* Normal saline in a volume of 0.5 ml/kg<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The time of the first analgesia request | minutes | 24 hours postoperative | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The total analgesic requirements (Ketorolac) | milligram | 24 hours postoperative | 
| Pain assessed by Visual Analogue Scale | Visual Analogue Scale: between 0 and 10 (0 representing no pain and 10 is the worst imaginable pain) | Postoperative: immediately after surgery, 2, 4, 6,10, 16, 24 hours postoperative | 
| Amount of fentanyl consumption | microgram | Intraoperative. | 
| Mean arterial blood pressure | millimeter mercury | intraoperative every 30 minutes, and postoperative at 2, 4, 6, 10, 16, 24 hours | 
| Heat rate | Beat per minute | intraoperative every 30 minutes, and postoperative at 2, 4, 6, 10, 16, 24 hours | 
| Sedation assessed by the observer's assessment of alertness & sedation score | sedation score (1-5): 5 = patient respond to name spoken in normal voice. 4 = patient asleep but arousable to normal tone voice. 3 = patient asleep but arousable to loud voice. 2 = patient asleep but arousable by mild prodding or shaking. 1 = comatose. | postoperative:10, 20, 30 minutes after extubation | 
| The Incidence of postoperative nausea and vomiting | percent | postoperative for 24 hours | 
| Patient satisfaction assessed by a visual analogue score | A score (0-10): 0 is the least satisfaction,10 the maximum satisfaction. | postoperative 24 hours after surgery |