Erector Spinalis Plane Block in Bariatric Surgery
Condition: Postoperative Pain; Opioid Consumption
MeSH terms: Pain, Postoperative
Study type: Interventional

Summary: 
      Background/objective: Bariatric surgery is often associated with moderate to severe pain. In
      obese individuals, opioids have the potential to induce ventilatory impairment; thus, opioid
      use needs to be limited. This study aimed to compare the novel ultrasound-guided erector
      spinalis plane block (ESPB) technique with controls in terms of intraoperative opioid
      consumption and postoperative pain control. Methods: A total of 63 patients with morbid
      obesity who underwent laparoscopic bariatric surgery were included in this randomized study.
      Patients were randomly assigned to the bilateral erector spina plane block (ESPB) group or
      the control group. To evaluate perioperative pain and to adjust opioid dose, analgesia
      nociception index (ANI) was monitored during surgery. Total opioid dose was recorded for each
      patient. In addition, pain was evaluated using visual analogue scale (VAS) scores for 24
      hours following the operation.
    

Detailed description: 
      Obesity represents a major disease burden and healthcare challenge globally due to its
      increasing prevalence over the last decades. From 1980 to 2013, worldwide prevalence of
      overweight/obesity increased by 27·5% for adults and 47·1% for children, resulting in an
      estimated global total number of obese/overweight individuals slightly more than two billion.
      Obesity is associated with serious conditions including cardiovascular disease, diabetes,
      some cancers, kidney disease, sleep apnea, gout, osteoarthritis, hepatobiliary disease,
      resulting in increased mortality and decreased life expectancy among obese individuals. On
      the other hand, weight loss leads to improvement of these conditions and outcomes. Life-style
      modifications with diet, exercise, and behavioral therapy, pharmacotherapy, and surgery are
      used for the management of obesity. Bariatric surgery represents an effective and a
      sustainable treatment modality in patients with morbid obesity, laparoscopic sleeve
      gastrectomy and gastric bypass being the most common procedures. However, these procedures
      are mostly associated with moderate to severe postoperative pain, which is often a
      combination of abdominal wall pain and visceral pain.Postoperative pain, when not adequately
      controlled, has unfavorable consequences such as impaired quality of life and recovery as
      well as increased risk of surgical complications and persistent postsurgical pain. Patients
      with morbid obesity represent a special group when it comes to perioperative pain management.
      These patients have a higher incidence of sleep-disordered breathing; therefore, opioids have
      the potential to induce ventilatory impairment resulting in increased morbidity/mortality.
      Stepwise and severity based-multi-modal analgesia with opioid-sparing approach can improve
      safety; thus, Enhanced Recovery After Surgery (ERAS) guidelines for bariatric surgery
      currently recommend opioid reduction in bariatric surgery. Both systemic analgesics and
      regional approaches such as transversus abdominis plane (TAP) block, intraperitoneal and
      wound modalities, and neuraxial techniques are being used for postoperative pain control in
      bariatric surgery with some success.

      Ultrasound-guided erector spinae plane block is a novel regional anesthesia technique where
      local anesthetic agent is injected deep into the erector spinae muscle to the fascial plane
      and allowed to diffuse in caudal and cranial direction. It has been shown effective in a
      number of conditions such as thoracic surgery/trauma, painful conditions of the limbs,
      cardiac surgery, breast surgery, and abdominal surgery. To date, only few studies examined
      the use of ESPB in bariatric surgery, all indicating potential benefits of the technique in
      terms of opioid sparing and pain control.

      This study aimed to compare bilateral ultrasound-guided erector spinalis plane block
      technique with controls who received bupivacaine injection to the trocar sites, in terms of
      intraoperative opioid consumption, postoperative pain control in the first 24 hours, and need
      for rescue analgesic.

      METHODS

      Patients Sixty-two patients with morbid obesity who underwent laparoscopic
      bariatric/metabolic surgery (sleeve gastrectomy or gastric bypass) were included in this
      randomized study.

      Patients were required to have a BMI ≥40 kg/m 2 and ASA physical status class 2 or 3.

      Exclusion/drop-out criteria were as follows: any complication (allergic reaction or local
      anesthesia-related complication), failure, or patient refusal during the block procedure;
      switch to open surgery or a change in the planned surgical protocol; analgesia nociception
      index (ANI) and/or bispectral index (BIS) monitoring not possible; or patient does not
      provide consent or withdraws consent at any point after inclusion.

      The study protocol was approved by local ethics committee (Ethics Committee for Clinical
      Studies, Marmara University, Medical Faculty; date, January 3, 2020; number, 09.2020.128).

      All patients provided informed consent prior to study entry and the study was conducted in
      accordance with the Declaration of Helsinki.

      Randomization to the study groups Patients were randomly assigned to the erector spina plane
      block (ESPB) group or the control group using sealed envelopes with 1:1 ratio. ESPB group
      received ultrasound-guided bupivacaine and lidocaine injection at T9 vertebral level before
      anesthesia induction. Control group received 5 ml 0.5% bupivacaine injection to each trocar
      site (total of 25 ml) at the beginning of the operation.

      Erector spinalis plane block technique

      An experienced anesthesiologist performed ESPB in all patients in sitting position
      bilaterally.

      A linear ultrasound probe (6-13 MHz) was used for ultrasound guidance. Injection was done
      using in-plane technique. A 22G block needle (100mm, B-Braun, Germany) was inserted 3- cm
      lateral to the T9 spinous process and advanced in cranio-caudal direction. To separate
      erector spina muscle from the transverse process, initially 1-2 ml saline was injected; then
      20ml 0.5% bupivacaine and 5 ml 0.2% lidocaine were injected following separation. Diffusion
      of the drugs in erector spina plane at cranio-caudal line was ensured. No analgesic or
      sedative was used during the procedure.

      Intraoperative anesthesia management Anesthesia was induced with propofol 2.5-3.5 mg/kg and 1
      mcg/kg bolus dose of remifentanil, which was followed by rocuronium 0.6 mg/kg to aid
      intubation. Corrected body weight (CBW) was used for the dose adjustment of propofol, and
      ideal body weight (IBW) was used for the dose adjustments of remifentanil and rocuronium.
      Total intravenous anesthesia with propofol and remifentanil was used for maintenance and the
      initial doses were as follows: propofol 6-10 mg/kg/h and remifentanil 0.5 mcg/kg/h. Propofol
      and remifentanil dose was adjusted to keep BIS between 40 and 45, and ANI between 50 and 70,
      respectively. Electrocardiography, non-invasive blood pressure, bispectral index (BIS,
      Medtronic, Mineapolis), and ANI were continuously monitored and recorded at every 30 minutes.

      To evaluate perioperative pain and to adjust opioid dose, ANI was continuously monitored
      throughout the surgical procedure. Two ANI electrodes were placed on the sternum and at the
      level of left nipple (to the same places with V1 and V5 ECG electrodes, respectively). Total
      remifentanil dose was recorded for each patient. Depth of anesthesia was monitored to adjust
      propofol dose using BIS (Aspect Medical Systems, Natick, Mass, ABD).

      Fifteen minutes before the completion of the surgical procedure, both groups received 1 g
      paracetamol and the control group received 150 mg tramadol.

      Assessments The primary outcome measure was total intraoperative opioid consumption, and the
      secondary outcome measure was the change in postoperative pain as assessed by 10-point visual
      analogue scale (VAS). A blinded investigator recorded self-assessed VAS scores of the
      patients upon awakening and at 6, 12, and 24 hours. In case VAS ≥ 4, rescue analgesic was
      given (100 mg tramadol). Timing of first analgesic requirement was recorded.

      Statistical analysis Data were analyzed using SPSS (Statistical Package for Social Sciences)
      version 21 software. Mean ± standard deviation or median (range) was used to express
      descriptive data. Both hypothesis tests and graphical method were used to test the
      distribution of continuous variables. Student t test for independent samples or Mann-Whitney
      U test was used to test between-group differences. Fisher's exact test was used to compare
      the two groups in terms of complication frequencies. Two-way ANOVA test for repeated
      measurements was used to examine the significance of differences between groups in
      postoperative VAS scores and intraoperative measurements over time. Two-sided p values
      &lt;0.05 were considered indication of statistical significance.
    

Intervention name(s): erector spina plane block (ESPB) group
Intervention type(s): Other
Intervention description(s): An experienced anesthesiologist performed ESPB in all patients in sitting position bilaterally.
A linear ultrasound probe (6-13 MHz) was used for ultrasound guidance. Injection was done using in-plane technique. A 22G block needle (100mm, B-Braun, Germany) was inserted 3- cm lateral to the T9 spinous process and advanced in cranio-caudal direction. To separate erector spina muscle from the transverse process, initially 1-2 ml saline was injected; then 20 ml 0.5% bupivacaine and 5 ml 0.2% lidocaine were injected following separation. Diffusion of the drugs in erector spina plane at cranio-caudal line was ensured. No analgesic or sedative was used during the procedure.
Other intervention name(s): non-block control group
Allocation: Non-Randomized
Intervention model: Crossover Assignment
Masking: Single (Participant)
Primary purpose: Prevention
Keywords: bariatric surgery; morbid obesity; ultrasound-guidance; erector spinalis plane block (ESPB); visual analogue scale (VAS) score; opioids