Neostigmine Versus Dexamethasone as Adjuvants to Lidocaine During Intravenous Local Anesthesia
Condition: Adjuvants, Anesthesia
Study type: Interventional
Phase: Phase 2/Phase 3

Summary: 
      Intravenous regional anesthesia (IVRA) is described firstly in 1908 by August Bier. It is
      simple, safe, reliable, less cost, efficient method in forearm surgery. The advantage of this
      method has fast return of motor and sensory function which enables patients for earlier
      discharge. However, this method has disadvantages such as tourniquet pain, insufficient
      muscle relaxation and postoperative analgesia.

      Lidocaine inhibits action potential propagation within neuronal tissue by binding to
      receptors in Na+ channels located on the nerve cell membrane. Lidocaine IVRA is safe and
      effective and is associated with a rapid onset (4.5 minutes) of anesthesia after injection
      and termination of analgesia (5.8 ± 0.5 minutes) once the tourniquet is deflated.

      Neostigmine is a typical cholinesterase inhibitor. It increases the level of acetylcholine
      (Ach) and indirectly stimulates both nicotinic and muscarinic receptors. In anesthesia,
      neostigmine is a drug that has been used for reversal of residual neuromuscular block.
      Administration of neostigmine by intrathecal and epidural routes has been found to cause
      analgesia by inhibition of the breakdown of Ach in the spinal cord.

      Dexamethasone is commonly used in anesthesia to prevent postoperative nausea and vomiting
      (PONV). Two recent meta-analyses have documented that dexamethasone also reduced
      postoperative pain and opioid requirement. Intravenous dexamethasone has also been shown to
      improve postoperative pain control in patients receiving spinal or epidural morphine.

      Hong et al reported that intravenous dexamethasone in combination with a caudal block with
      ropivacaine prolonged the duration of postoperative analgesia without adverse effects in
      children undergoing orchidopexy. So the investigators expect that addition of dexamethasone
      or neostigmine will affect duration and postoperative analgesia in bier block.
    

Detailed description: 
      This study will be a prospective clinical randomized controlled double-blind study using a
      computer-generated randomization. Neither the doctor "investigator" nor the participant
      "patient" will be aware of the group allocation or the drug used. The study drugs will be
      prepared by one of the supervisor anesthesiologists (not included in the procedure,
      observation or data collection).

      The study will be carried out in Assiut University Hospital after approval from our local
      ethical committee.

      Patients

      The patients will be classified in two groups:

      According to sample size calculator. Group D: will include 30 patients and will receive
      intravenous 3mg/kg lidocaine 2 % (diluted with normal saline to 40 ml) + 8 mg dexamethasone
      for bier block.

      Group N: will include 30 patients and will receive intravenous 3mg/kg lidocaine 2 % (diluted
      with normal saline to 40 ml) + 0.5 mg neostigmine for bier block.

      Methods

      Before the procedure, the patient should be:

        -  Starved for 6-8 hours.

        -  Monitored closely (standard monitoring applied: HR, NIBP, SaO2 and RR)

        -  Adequately informed about the procedure and have consented to it.

      The equipments required for IVRA include:

      - Pneumatic tourniquet (checked for leaks before the procedure) and a pressure gauge.

        -  Esmarch bandage or Rhys-Davis exsanguination.

        -  Local anesthetic solution and the adjuvants.

        -  Resuscitation equipments and drugs.

      Technique:

      IVRA of the arm: a 22 G cannula is placed intravenously as distal as possible in the arm to
      be anesthetized. Venous access is established in the opposite arm to allow administration of
      fluids or other drugs if necessary. The double tourniquet (two tourniquets each 6 cm wide) or
      a single one (14 cm wide) is applied on the operated arm with generous layers of padding,
      ensuring that no wrinkles are formed and the tourniquet edges do not touch the skin.

      The arm is exsanguinated either by using the Esmarch bandage or a Rhys-Davis exsanguinator.
      If this is impossible, exsanguination can be achieved by elevating the arm for 2-3 minutes
      while compressing the axillary artery. The distal tourniquet is inflated to at least 100 mm
      Hg higher than the patient's systolic blood pressure (250 - 300 mmHg). The proximal
      tourniquet is inflated to the same pressure.

      After ensuring inflation, the distal cuff is deflated. Before injecting local anesthetic, it
      must be confirmed that no radial pulse is palpable. The local anesthetic is then injected
      slowly. A standard volume for injection into the upper limb is 40 ml, which can be increased
      to 50 ml in a fit, large adult.

      If the injection is too rapid, the venous pressure may exceed the tourniquet pressure and the
      local anesthetic solution may escape into the systemic circulation. Surgical anesthesia is
      usually achieved within 15 minutes. The distal tourniquet, which overlies part of the
      anesthetized arm, can then be inflated and the proximal one deflated to relieve tourniquet
      pain. The cuff should not be deflated until 20 minutes after local anesthetic injection
      because systemic toxic doses of local anesthetic may occur.

      Cuff deflation should be performed in cycles with deflation/inflation times of less than 10
      seconds until the patient no longer exhibits signs of systemic toxicity (e.g. tingling of the
      lips, tinnitus or drowsiness). Therefore, the patient should be monitored closely for 30
      minutes following tourniquet release. So, the investigators expect that addition of
      dexamethasone or neostigmine will affect duration and postoperative analgesia.

      Data collection:

        1. Patient's data: include patient's gender, age, weight, height, BMI and ASA
           classification.

        2. Preoperative data:

             1. Basic Monitoring: heart rate (HR), non-invasive blood pressure (NIBP), arterial
                oxygen saturation (SaO2), respiratory rate (RR) will be recorded.

             2. Preoperative investigations: prothrombin time, prothrombin concentration and INR to
                avoid any risk of internal bleeding.

             3. Basal assessment of motor power and sensation of the limb:

        1. Motor power: Motor block was evaluated by thumb abduction (radial nerve), thumb
           adduction (ulnar nerve), thumb opposition (median nerve), and flexion at the elbow
           (musculocutaneous nerve) on a 3-point scale for motor function (0: normal motor
           function, 1: reduced motor strength but able to move fingers, 2: complete motor block).

        2. Sensation: Sensory block (4 nerves) was assessed by ice packs using a 3-point scale: 0:
           normal sensation, 1: loss of sensation of cold (analgesia), 2: loss of sensation of
           touch (anesthesia).

           d- The standard value of visual analogue scale will be set as the score during passive
           exercise before the surgery.

        3. Introperative data:

             1. Basic Monitoring: heart rate (HR), non-invasive blood pressure (NIBP), arterial
                oxygen saturation (SaO2), respiratory rate (RR) will be recorded every 10 minutes
                till the end of surgery.

             2. Sensory and motor block: Sensory and motor blocks will be evaluated every 5 minutes
                until 20 minutes after injection.

           Onset time will be defined as the time interval between the end of total local
           anesthetic administration and complete sensory block. Complete sensory block will be
           defined by anesthetic block (score 2) on all nerve territories.

           Complete motor block will be defined as absence of voluntary movement on hand and
           forearm (score 0).

           c- Duration of surgery.

        4. Postoperative data:

             1. Duration of sensory and motor block:

                Duration of sensory block will be defined as the time interval between the end of
                local anesthetic administration and the complete resolution of anesthesia on all
                nerves.

                Duration of motor block will be defined as the time interval between the end of
                local anesthetic administration and the recovery of complete motor function of the
                hand and forearm.

             2. Duration of analgesia: interval between onsets of the block to the time of the
                first analgesic requirement.

             3. Analgesia assessment:

           Postoperatively, a Post-Anesthesia Care Unit (PACU) nurse will assess the quality of
           analgesia. The pain score will be recorded using the Visual Analouge Scale (VAS) 2, 4,
           6, 12 and 24 hours after surgery. Significant pain is defined as one that has a score of
           ≥ 4 and as a consequence required a supplementary dose of analgesia. Intravenous
           Paracetamol 15 mg/kg, will be administered and recorded.

           d- Documentation of any complications: Includes local anesthetic toxicity & drug
           additives complications.

           Local anesthetic toxicity:

           • Initial symptoms are subjective and include perioral tingling or numbness,
           lightheadedness, tinnitus, metallic taste, slurred speech, auditory and visual
           disturbances.

           • Minor symptoms usually do not require treatment. If any of these occur observe patient
           closely and identify any potential reasons for systemic toxicity eg: check for cuff
           failure - re-inflate.

             -  Significant neurotoxicity: Objective signs are usually excitatory: twitching,
                fasciculation and seizures:

                - Check for cuff failure - re-inflate immediately

                - Administer Midazolam 2.5-5.0 mg iv

                  -  Support the ABC's as indicated Most seizures are self-limiting but can be
                     potentiated by hypoxia, acidosis and hypercarbia so these should be treated
                     aggressively.

             -  Significant cardiotoxicity: if occurs (eg: hypotension, bradycardia and
                arrhythmias):

           Give oxygen and adopt an ACLS approach Check for cuff failure - re-inflate immediately
           Bicarbonate may be indicated to address acidaemia.

           Drug additives complications:

           All patients will be monitored for any complications that may occur from any adjuvant
           drugs used in the study and will be treated promptly.

           Statistical analysis All data will be collected and analyzed using SPSS version 20
           (SPSS, Inc., Chicago, Illinios, USA). Normally distributed data will be expressed as
           mean ± standard deviation, range, numbers and percentages. A probability (p) value of
           less than 0.05 will be considered statistically significant.
    

Intervention name(s): Neostigmine; Dexamethasone
Intervention type(s): Drug; Drug
Intervention description(s): Patients will receive intravenous 3mg/kg lidocaine 2 % (diluted with normal saline to 40 ml) + 0.5 mg neostigmine for Bier block.; Patients will receive intravenous 3mg/kg lidocaine 2 % (diluted with normal saline to 40 ml) + 8 mg dexamethasone for Bier block.
Intervention MeSH terms: Dexamethasone; Neostigmine
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Prevention
Keywords: Neostigmine; Dexamethasone; Intravenous Local Anesthesia