Midazolam in Supraclavicular Brachial Plexus Block
Condition: Forearm Surgeries
Study type: Interventional
Phase: Phase 2

Summary: 
      An effective brachial plexus block (BPB) provides a useful alternative to general anesthesia
      for upper arm surgery producing complete muscular relaxation. It provides surgical anesthesia
      in upper extremity surgery, post-operative analgesia and chronic pain management. In addition
      to surgical procedure on conscious patients and early eating after the procedure make
      regional anesthesia more attractive.

      Brachial plexus block also maintains stable intraoperative hemodynamic and associated
      sympathetic block. The sympathetic block decreases postoperative pain, vasospasm and edema.
      The nerve of brachial plexus may be blocked anywhere along its course. The approach for
      blocking brachial plexus nerve is interscalene, supraclavicular, infraclavicular and axillary
      approach.

      Supraclavicular approach for blockade of the brachial plexus is the most commonly used
      approach in providing surgical anesthesia. In recent years, the technique has gained
      importance as regional anesthetic technique for surgical, diagnostic and therapeutic purposes
      in interventional pain management. It includes blocking of the brachial plexus where it is
      most compactly arranged, with fewer requirements of the anesthetic solution and rapid onset
      of action. Supraclavicular nerve block is technically easy to perform because of reliable and
      fixed landmark but association of pneumothorax is a profound complication.

      The extent of blockade following injection into the sheath surrounding the brachial plexus
      may depend on the volume and concentration of local anesthetic (LA) used. Because of
      bupivacaine long duration of action, it is used most frequently among local anesthetics for
      BPB.

      Inevitably, the effects of single-injection BPB dissipate after several hours unmasking the
      moderate-to-severe pain of the surgical insult. Efforts to prolong BPB duration by increasing
      LA dose are limited by their narrow therapeutic window and indeed may not be effective as
      recent studies have demonstrated equivalent analgesic duration with volumes as low as 5 ml.

      Midazolam is known to produce antinociception and potentiate the effect of LA when given in
      neuraxial block. It produces this effect by its action on Gamma Aminobutyric Acid-A (GABA-A)
      receptors and also on the peripheral nerves which contain these receptors.

      Several studies showed midazolam to be effective when used in intrathecal, epidural and
      caudal blocks and now recently midazolam with bupivacaine has been found to improve analgesic
      characteristics in peripheral blocks compared to bupivacaine alone. Due to the high blood
      concentration of benzodiazepine through conventional routes and profound sedation, proper
      assessment of analgesic effect was difficult to obtain. With the advent of the less toxic
      water soluble benzodiazepine (midazolam), it became possible to use it directly over the
      nerve tissues.
    

Detailed description: 
      The day prior to surgery, all patients will undergo pre-anesthetic checkup including detailed
      history, thorough general, physical, systemic examination and weight of the patient. All
      patients will be kept nil by mouth for at least 6 hours.

        -  Written consent, coagulation profile, intravenous line, emergency resuscitation
           equipments including airway devices, advanced cardiac life support drugs for LA toxicity
           will be available.

        -  Patients will be monitored using standard monitoring (ECG, non-invasive blood pressure
           and pulsoximetry)

        -  All patients will be lightly sedated with 1 mg midazolam I.V. SonoAce 6 ultrasound
           machine with high frequency linear probe will be used in our study.

      Palpation of the subclavian artery in the supraclvicular fossa, just lateral to the
      sternocledomastoid and above the clavicle (landmark located one finger or 1 cm above the
      clavicle at the junction of inner 2/3 and outer 1/3 of clavicle).

      Position to perform supraclavicular BPB; the anesthetist will stand behind the patient's
      head, with the ultrasound machine on the side being blocked. The head of the bed is slightly
      raised to allow the shoulder to drop somewhat the patient's head will be turned to the
      opposite side, resting directly on the table without a pillow, the hand holding the probe
      will rest against the patient's jaw, the probe is placed in the supraclavicular fossa in a
      coronal oblique plane, the needle will be inserted from the lateral side, The pulsating
      hypoechoic supraclavicular artery is identified, lying above the hyperechoic first rib, the
      probe is then angled until both the first rib and the pleura are also seen simultaneously,
      The nerve structures (trunks or divisions) are usually visualized as a collection of
      hypoechoic round structures (a bunch of grapes) lying superior and postero-lateral to the
      subclavian artery. A 3 cm long 22 G needle with 10 cc syringe filled with respective LA agent
      will be inserted directing downward, forward and medially at the angle of 20° to the skin
      till the parasthesia elicited in the hand or the 1st rib hit, then the needle will be fixed
      at that point. After the negative aspiration respective agents will be given. A gentle
      massage over the area will be done with an idea of uniform spread. All brachial plexus
      injections will be administered slowly with repeated aspiration to prevent or detect early
      intravascular injection. The end of the injection will be considered time 0.
    

Intervention name(s): Bupivacaine; Midazolam; Midazolam
Intervention type(s): Drug; Drug; Drug
Intervention description(s): 20 ml of 0.5% bupivacaine using supraclavicular BPB.; midazolam 0.03 mg/kg dissolved in 5 ml normal saline (0.9%) using supraclavicular BPB; 0.03 mg/kg of midazolam by I.V. route
Intervention MeSH terms: Midazolam; Bupivacaine
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Group A: patients will receive 20 ml of 0.5% bupivacaine + 5 ml normal saline (0.9%) using supraclavicular BPB.
Group B: patients will receive 20 ml of 0.5% bupivacaine + midazolam 0.03 mg/kg dissolved in 5 ml normal saline (0.9%) using supraclavicular BPB.
Group C: patients will receive 20 ml of 0.5% bupivacaine + 5 ml normal saline (0.9%) using supraclavicular BPB + 0.03 mg/kg of midazolam by I.V. route at the same time of the block.
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Prevention
Keywords: midazolam; brachial plexus block