Comparison of the Effectiveness of Two Different Block in the Management of Postoperative Analgesia After Lumbar Spinal Surgery

Objective: The aim of this study was to compare the efficacy of US-guided Classic TLIP block and Posterior QLB (QL2) block for postoperative analgesia management after LDH surgery. Our primary aim is to determine the 24-hour opioid requirement, and our secondary aim is to; compare postoperative pain scores (NRS), to evaluate side effects (allergic reaction, nausea, vomiting) associated with opioid use and complications that may occur due to block.

Content: Lumbar spinal surgery is one of the most common operations performed for the treatment of back and leg pain (1). Pain control is an important part of the treatment in these patients who may develop chronic pain. In patients undergoing surgery for lumbar disc herniation (LDH), severe pain may occur in the postoperative period, especially in the operation area, and this pain may become chronic (2). Effective postoperative pain control reduces complications such as hospital-acquired opioids are widely used analgesic agents. Parenteral opioids are preferred for the treatment of acute postoperative pain in most patients who have surgery. Although opioids are widely used in the treatment of acute postoperative pain. They may cause opioid-related adverse events (ORAE) such as nausea, vomiting, allergic reactions, sedation, and respiratory depression (3). In order to reduce the use of systemic opioids, regional anesthesia techniques may be preferred with the increase in the use of ultrasound (US) in daily anesthesia practice (4).

Quadratus lumborum block (QLB) performed under US guidance is an interfacial plane block defined by Blanco (5). This block is used in the management of analgesia after abdominal and lumbar surgery (5-9). Local anesthetic solution is injected around the quadratus lumborum muscle to block the thoracolumbar nerves. In posterior OLB (QL2) block, local anesthetic solution is injected from the posterior part of the muscle and spreads between the Quadratus lumborum and Erector spina muscles (6). Since it is performed under US guidance, it is an easy and reliable method with a low complication rate. and thromboembolism, as it provides early mobilization and early discharge.Thoracolumbar interfacial plane (TLIP) block is a regional analgesia technique performed under US guidance, which was defined by Hand et al. in 2015 (10). Ueshima et al. retrospectively demonstrated that this technique produces effective analgesia after lumbar laminoplasty.

reported in their study (11). In the classical technique, local anesthetic infiltration is performed between the Multifidus and Longissimus muscles in the 4th Lumbar (L4) vertebral region (10). There is no study in the literature comparing classical TLIP block and QL2 block.

In this study, it was aimed to compare the effectiveness of US-guided Classic TLIP block and Posterior QLB (QL2) block for postoperative analgesia management after LDH surgery. Our primary aim is to determine the 24-hour opioid requirement, and our secondary aim is to; to compare postoperative pain scores (NRS), to evaluate side effects (allergic reaction, nausea, vomiting) associated with opioid use and complications that may occur due to block Material and Method Sixty patients with ASA classification I-II, aged 18-65 years, scheduled for lumbar discectomy + laminectomy under general anesthesia will be included in this prospective, randomized study. Patients with a history of bleeding diathesis, taking anticoagulant therapy, allergic or sensitive to local anesthetic and opioid drugs, patients with infection in the area to be blocked, patients who have had previous lumbar surgery, patients using gabapentinoids or corticosteroids, patients who cannot use a patient-controlled anesthesia device, patients with suspected pregnancy , pregnant or lactating mothers and patients who do not accept the procedure will be excluded from the study.

1. General anesthesia After the patients are taken to the operating room, all patients will be premedicated with 2 mg of intravenous midazolam. In anesthesia induction, 2-2.5 mg kg-1 iv propofol, 1-1.5 mcg kg-1 iv fentanyl, 0.6 mg kg-1 iv rocuronium will be intubated. The patient will then be placed in the prone position. Anesthesia will be maintained with 1-2% sevoflurane and 50 mcg/hour remifentanil in a 50% oxygen-air mixture. Mechanical ventilator settings will be adjusted so that tidal volume is 6-8 ml/kg, maximum airway pressure is 30 cmH2 O, end tidal CO2 is 30-35mmHg. If the pulse or mean blood pressure increases by 20% from the preoperative value, a bolus of 25 mcg fentanyl and 0.1 mg kg-1 rocuronium will be administered. Lumbar discectomy + laminectomy will be performed by the same surgical team with the same routine surgical procedure. Patients will receive an analgesic regimen as described post-induction and pre-extubation. To prevent nausea and vomiting, iv 4 mg of ondansetron will be given. Patients with adequate spontaneous breathing will be taken to the postoperative recovery unit after extubating. Patients who reach 12 points in Aldrete scoring will be sent to the service. Before coming to the operating room, the patients will be randomly divided into 2 groups (Group Q= QL2 block group, Group T= Classic TLIP group) each containing 26 patients, using a sealed envelope method.

2. Block technique The block that we use routinely, in accordance with the guidelines and valid, will be applied to the patient in the preoperative block room 30 minutes before the operation starts (5-9).

   1. Posterior QLB process; After aseptic conditions are provided, the convex US probe will be covered with a sterile sheath, and an 80-100 mm block needle will be used. After imaging the abdominal muscles with the anterior approach, the needle will be advanced in the Petit triangle and 1-2 ml of saline will be injected into the posterior border of the quadratus lumborum muscle. After the block location is confirmed, 20 ml of local anesthetic infiltration at a concentration of 0.25% will be applied. The same procedure will be applied to the other side. A total of 30 ml of local anesthetic solution will be used.
   2. Classic TLIP block: Operation after providing aseptic conditions, the high frequency linear US probe will be covered with a sterile sheath, and a 50 mm block needle will be used. The ultrasound probe will be placed vertically at the level of the L3 vertebra. After visualizing the guiding point spinous process and interspinal muscles, the probe will be moved laterally to visualize the longissimus and multifidus muscles. By using the in-plane technique, the block needle will be directed from medial to lateral, and after reaching the interfacial area between the longissimus and multifidus muscles, the block area will be confirmed by administering 5 ml of serum physiologically. Then, 20 ml of 0.25% local anesthetic will be administered. The same procedure will be applied to the other side. A total of 40 ml of local anesthetic solution will be used.
3. Postoperative analgesia management After anesthesia induction, 1 g iv Pracetamol before surgical incision and 20 mg iv Tenoxicam iv 20 mg 30 minutes before the end of the surgical procedure will be administered for postoperative analgesia. In the postoperative period, paracetamol 3x1 gr iv will be administered to the patients and iv Morphine infusion will be performed with a patient-controlled analgesia (PCA) device. By adding 0.5 mg/ml of morphine in the serum physiological, 1 mg bolus, 8 minutes lock time, and a maximum of 6 mg morphine per hour will be adjusted (12). Postoperative patient evaluation will be performed by another non-interventional anesthetist.

Postoperative pain assessment will be made using the NRS scoring (0 = no pain, 10 = most severe pain felt). Resting and mobile NRS scores will be recorded at 0, 2, 4, 8, 16, and 24 hours. NRS score \< 4 will be targeted.

Sedation level will be monitored on a 4-point sedation scale (0=wake, eyes open, 1=sleepy but responds to verbal stimuli, 2=sleepy and difficult to awaken, 3=sleepy, cannot be woken by shaking).

Additional analgesic need, side effects such as nausea, vomiting, itching and complications that may occur due to block will be recorded.

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