A Comparative Study Between Different Volumes During Erector Spinae Block for Pain Control
Condition: Postoperative Pain Management
MeSH terms: Pain, Postoperative
Study type: Interventional

Summary: 
      Since its first description by Forero et al. there have been many articles and case reports
      including an increasingly number of indications for the ESP block: chronic and acute pain
      treatment, rib fractures management in the emergency setting, treatment of abdominal surgical
      pain, hip arthroplasty , analgesic management in breast surgery,or in spinal surgery.Although
      ESP block successfully reduced postoperative opioid consumption in clinical reports, no
      studies thus have investigated the optimum volume of bupivacaine for ESP block as regard a
      review of the medical literature on December 27th, 2017 that searched terms in 14 articles
      clearly stated the volume of the bolus and the spread of the anesthetic after an injection of
      LA, the volume needed to cover one dermatome widely varies from 2.5 mL to 6.6 mL, with a
      median value of 3.4 mL. Furthermore, the maximum number of dermatomes reached by a single
      bolus in ESP was of 9 dermatomes after a 30 mL bolus.

      Thus, in this study, the investigators evaluate the effect of ESP block which will be
      performed by using three different volumes (2.5, 3.4 ,6.6 ml/segment) of bupivacaine with the
      same concentration ,technique ,site of injection and operation.
    

Detailed description: 
      INTRODUCTION In recent years a number of important fascial plane blocks have been described
      blocking the dorsal, lateral and anterior cutaneous nerves of the thorax and abdome].The
      advantage common to all of these blocks is that they are technically easier to perform with
      lower risk for serious complications.Since its first description by Forero et al. there have
      been many articles and case reports including an increasingly number of indications for the
      ESP block: chronic and acute pain treatment , rib fractures management in the emergency
      setting , treatment of abdominal surgical pain , hip arthroplasty , analgesic management in
      breast surgery ,or in spinal surgery.The ESP block targets the erector spinae plane, which
      lies in the chest wall between the anterior surface of the cephalo caudal oriented erector
      spinae muscles and the posterior surface of the spinal transverse processes. LA is deposited
      in the fascial plane deep to the erector spinae muscle and superficial to the tips of the
      transverse processes, from where it diffuses to the dorsal and ventral rami of spinal nerves,
      achieving an extensive multi-dermatomal sensory block of the posterior, lateral, and anterior
      thoracic wall .Chin et al reported that an injection of 20 ml into the ESP produces clinical
      and radiographic evidence of spread that extends at least three vertebral levels cranially
      and four levels caudally from the site of injection.A study with magnetic resonance imaging
      demonstrated and confirmed that its mechanism of action is likely linked to the
      transforaminal and epidural spread, which may be a potential advantage because the ESP block
      provides abdominal visceral analgesia unlike the others .beside its ability to spread to
      paravertebral and intervertebral spaces and ability to block the sympathetic nerve fibers.
      the ESP block is considered as a peri-paravertebral regional anesthesia technique.LAs, is
      injectted with volumes ranging from 20 mL to 40 mL, and concentrations ranging from
      0.25%-0.5%.even though a higher LA concentration might allow for better diffusion into the
      paravertebral space .

      Open surgery remains common for patients requiring radical or partial nephrectomy and is
      associated with a high incidence of intense immediate postoperative pain and chronic pain in
      the months following surgery. ESP block was for open partial nephrectomy with excellent
      results both in the intraoperative and postoperative period, with a large reduction in the
      use of opioids.

      Although ESP block successfully reduced postoperative opioid consumption in clinical reports,
      no studies thus have investigated the optimum volume of bupivacaine for ESP block as regard a
      review of the medical literature on December 27th, 2017 that searched terms in 14 articles
      clearly stated the volume of the bolus and the spread of the anesthetic after an injection of
      LA, the volume needed to cover one dermatome widely varies from 2.5 mL to 6.6 mL, with a
      median value of 3.4 mL. Furthermore, the maximum number of dermatomes reached by a single
      bolus in ESP was of 9 dermatomes after a 30 mL bolus.

      Thus, in this study, the investigators evaluate the effect of ESP block which will be
      performed by using three different volumes (2.5, 3.4 ,6.6 ml/segment) of bupivacaine with the
      same concentration ,technique ,site of injection and operation.

      Methodology:

      Eighty Patients, aging from 18-50 years with ASA physical status I and II, undergoing open
      simple nephrectomy will be included and randomly distributed into 4 groups with 20 patients
      for each group where group C will not receive erector spinae block and so will be the control
      group while groups which will receive erector spinae block will be E1,E2,E3 and will receive
      0.25% bupivacaine with volumes of 2.5,3.4,6.6 ml/segment respectively.

      The day before surgery, all patients will be instructed to fast for 6-8 hours. On the day of
      the operation,the patient will arrive to the preparation room 1 hour before operation,to
      allow time for the block procedure and a minimum of 45 minutes after the block to pass, an 18
      G cannula insertion, a start of IV fluid drip, and premedication with 0.02-0.03 mg/kg
      intravenous midazolam will be done. All basic monitoring will be applied (ECG/HR/SpO2/NIBP),
      and baseline values for HR, SPO2 ,SBP,DBP and MAP will be documented then every 5 minutes
      till the patient reaches the operating room.

      A mark will be applied on the required level (T8), the midline (spinous processes) and the
      injection points 3 cm from midline.While the patient is in a sitting position with support
      from a member of staff, Preparation of the field with iodine will be made. Using ultrasound
      guidance with a 6-10 MHz linear probe anatomical landmarks will be identified including the
      transverse process at T8 level and the three layers of muscles from posterior to anterior:
      trapezius-rhomboid-erector spinae. After subcutaneous lidocaine 2% injection a 22-G spinal
      needle will be inserted under ultrasound guidance in plane, aiming towards the transverse
      process. After a Gentle contact with the transverse process, the volume of 0.25% bupivacaine
      will be injected according to each group 2.5, 3.4 ,6.6 ml/segment in increments with careful
      repetitive aspiration to avoid intravascular injection.

      Spread of the local anesthetic will be monitored by U/S anterior to erector spinae muscles
      (dividing erector spinae muscles from transverse process with caudal and cephalic spread)
      then the end point of local anesthetic will be marked and the corresponding covered level
      will be assessed caudal and cephalic from T8.onset of the block will be tested by pin brick
      test every 10 minutes after performing the block maximum 30 minutes otherwise it will be
      considered failed block and documented for each group while dermatomal spread will be
      assessed by pin brick test 30 minutes after onset of the block and will be documented.

      Then the patient will be transferred to the OR. All basic monitoring will be applied
      (ECG/HR/SpO2/NIBP) while monitoring of end-tidal CO2, neuromuscular block and depth of
      anesthesia using Bispectral index (BIS) monitor will be initiated after induction of
      anesthesia and values will be recorded for HR, SPO2 ,SBP,DBP ,MAP and ETCO2 every 5 minutes
      till the end of the surgery then for 30 minutes from time of reaching PACU.

      General anesthesia will be inducted with 2 mg/kg propofol, 1μg/kg fentanyl and 0.5 mg/kg
      atracurium to facilitate endotracheal intubation. After intubation the lungs will be
      mechanically ventilated to maintain the ETCO2 35-40 mmHg. Then Patient positioned in the
      lateral position. Anesthesia will be maintained with isoflurane keeping the ET concentration
      of isoflurane 1-2% to maintain the BIS value 40-60. Atracurium besylate top-up doses 0.1mg/kg
      will be given based on the response to train of four ulnar nerve stimulation. Additional
      fentanyl dose of 0.5 µg/kg IV for maximum of 2 µg/kg will be given if HR and or BP increased
      more than 20% from baseline in response to surgical stimulation and the total dose of
      fentanyl will be recorded.

      The patient's pain will be monitored and documented using the Numerical Rating Score (NRS)
      for pain at times 0,30 minutes, 1, 2, 4, 6, 8, 10, 12, 18 and 24 hours. The "zero" point of
      time will be the moment the patient recovered from general anesthesia. Time to first
      analgesic requirement will be recorded. Rescue medication for pain will be given on demand
      including 1 g paracetamol IV when NRS >/= 2 but < 4 and if NRS is 4 or more a 5 mg morphine
      IV with maximum dose of 10 mg every 6 hours and the total consumption of these medications
      will be recorded.
    

Intervention name(s): erector spinae block by 0.25% bupivacaine
Intervention type(s): Procedure
Intervention description(s): A mark will be applied on the required level (T8), the midline (spinous processes) and the injection points 3 cm from midline.While the patient is in a sitting position with support from a member of staff, Preparation of the field with iodine will be made. Using ultrasound guidance with a 6-10 MHz linear probe anatomical landmarks will be identified including the transverse process at T8 level and the three layers of muscles from posterior to anterior: trapezius-rhomboid-erector spinae. After subcutaneous lidocaine 2% injection a 22-G spinal needle will be inserted under ultrasound guidance in plane, aiming towards the transverse process. After a Gentle contact with the transverse process, 0.25% bupivacaine is injected in increments with careful repetitive aspiration to avoid intravascular injection.
Other intervention name(s): erector spinae plane block
Intervention MeSH terms: Bupivacaine
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: 4 groups with 20 patients for each group where group C will not receive erector spinae block and so will be the control group while groups which will receive erector spinae block will be E1,E2,E3 and will receive 0.25% bupivacaine with volumes of 2.5,3.4,6.6 ml/segment respectively.
Masking: Double (Care Provider, Investigator)
Primary purpose: Prevention
Keywords: erector spinae; -block; volume; pain