Analgesic Efficacy of Intertransverse Process Block Versus Erector Spinae Plane Block

Study Objective: This research aims to obtain objective data to demonstrate theeffectiveness of two regional block techniques in acute pain management. The primaryobjective is to compare the effects of Intertransverse Process Block (ITP) and ErectorSpinae Plane Block (ESP) on Visual Analog Scale (VAS) scores in patients undergoingrobotic colorectal surgery. Secondary outcomes include evaluating the impact of theseblocks on total opioid consumption within the first 24 hours, requirement for rescueanalgesia, block‐related and systemic complications (hematoma,pneumothorax, localanesthetic systemic toxicity, vascular puncture, infection), patient and surgeonsatisfaction assessed using a Likert scale, quality of recovery assessed using the QoR‐15questionnaire, and incedence of postoperative nausea and vomiting.Materials and Methods: This prospective, randomized clinical study will include voluntarypatients aged 18‐65 years, classified as American Society of Anesthesiologists (ASA)physical status I‐III, with a body mass index (BMI) <35 kg/m². All participants will beinformed about the study protocol in detail, and written informed consent will beobtained prior to inclusion. Patients will receive instruction on the use of the VAS forpain assessment, where 0 denotes no pain and 10 denotes the worst imaginable pain.Patients who meet the exclusion criteria will be withdrawn from the study. Participantswill be randomly assigned to one of two groups using a computer‐ generated simplerandomization method (https://www.randomizer.org). Randomization will be performed by ateam member uninvolved in patient care, who will also prepare sealed opaque envelopes toconceal group allocation until shortly before block administration.Study Groups and Block Procedures: Group ITP will receive a bilateral ITP block, andGroup ESP will receive a bilateral ESP block. All patients will be monitored withelectrocardiography, peripheral oxygen saturation (SpO#), and non‐invasive blood pressureprior to the block. Premedication with intravenous midazolam (0.02 mg/kg) will beadministered.ITP Block :Intertransverse Process Block (ITP) block will be performed 30 minutes prior to surgerywith the patient in a sitting position. After skin disinfection with chlorhexidine, theskin and subcutaneous tissues will be anesthetized using 2‐4 mL of 1% lidocaine(Aritmal®, Osel Pharmaceuticals, Turkey). A linear ultrasound probe (Mindray DiagnosticUltrasound System, Model DC‐T6) will be positioned along the medial border of spinousprocesss level of the 10th thoracic vertebrae.Anatomical landmarks, including the erector spinae muscle, transverse processes, andsuperior costotransverse ligament complex at the T10 level, will be identified. Using anin‐plane approach, a 21G 0.8x100 mm echogenic insulated needle (Echoplex®+ , Vygon SA,Écouen, France) will be inserted through the erector spinae muscle toward theintertransverse tissue complex located between the superior costotransverse ligament andthe transverse processes. Proper needle placement will be confirmed with the injection of1‐2 mL isotonic saline demonstrating separation within the intertransverse plane. Uponconfirmation and negative aspiration, 20 mL of 0.25% bupivacaine hydrochloride (Buvasin®,Vem Pharmaceuticals, Turkey) will be administered on each side under ultrasound guidance.The block performance time, defined as the duration from initial ultrasound probe contactwith the skin to the final withdrawal of the needle following injection, will berecorded.ESP Block:The Erector Spinae Plane Block (ESP) will be performed 30 minutes prior to surgery withthe patient in a sitting position. After skin disinfection with chlorhexidine, the skinand subcutaneous tissues will be anesthetized using 2‐4 mL of 1% lidocaine (Aritmal®,Osel Pharmaceuticals, Turkey). A linear ultrasound probe (Mindray Diagnostic UltrasoundSystem, Model DC‐T6) will be positioned along the medial border of spinous processs levelof the 10th thoracic vertebrae.Anatomical landmarks, including the trapezius muscle, rhomboid major muscle (RMM),erector spinal muscle and transverse processes of the 10th thoracic vertebrae will beidentified. Using an in‐plane approach, a 21G 0.8×100 mm echogenic insulated needle(Echoplex®+ , Vygon SA, Écouen, France) will be inserted into the fascial plane betweenthe erector spinal muscle and 10th thoracic vertebrae. Proper needle placement will beconfirmed with the injection of 1‐2 mL isotonic saline. Upon confirmation and negativeaspiration, 20 mL of 0.25% bupivacaine hydrochloride (Buvasin®, Vem Pharmaceuticals,Turkey) will be administered on each side under ultrasound guidance.General Anesthesia Upon entry into the operating room, patients will be monitored withelectrocardiography, peripheral oxygen saturation (SpO2), and non‐invasive bloodpressure. Anesthesia will be induced with intravenous propofol (2 mg/kg, PolifarmaPharmaceutical Industry and Trade Inc., Ergene, Turkey), fentanyl citrate (1.5 mcg/kg,Polifarma Pharmaceutical Industry and Trade Inc., Ergene, Turkey), and rocuronium bromide(0.6 mg/kg, Muscuron®, Koçak Farma Pharmaceutical and Chemical Industry Co., Turkey).Anesthesia maintenance will be provided using 6% desflurane in a 40% oxygen‐air mixtureand a continuous remifentanil infusion at 0.05 mcg/kg/min. Mechanical ventilationsettings will be adjusted to deliver a tidal volume of 6‐8 mL/kg with end‐tidal CO#maintained at 30‐35 mmHg. Anesthetic depth will be monitored continuously using aBispectral Index (BIS™) monitor (Medtronic plc, Dublin, Ireland), targeting a BIS valueof 40‐60. If heart rate or mean arterial pressure increases >20% from baseline, theremifentanil dose will be titrated accordingly.Thirty minutes before the end of surgery, all patients will receive 15 mg/kg ofintravenous paracetamol (e.g., Paracerol®, Polifarma Pharmaceutical Industry and TradeInc., Ergene, Turkey) and 1 mg/kg of intravenous tramadol. To prevent nausea andvomiting, 0.15 mg/kg of intravenous ondansetron will be administered. Patients withadequate spontaneous ventilation will be extubated and transferred to the post‐anesthesiacare unit (PACU). Hemodynamic Monitoring Heart rate, systolic blood pressure, diastolicblood pressure, mean arterial pressure, and oxygen saturation will be recorded at thefollowing time points: pre‐induction (baseline), 5 minutes after induction, 5 minutesafter surgical incision, 15 minutes after incision, and at the end of surgery.Postoperative Pain and Analgesic Use Pain will be assessed using the VAS at rest (static)and during movement (dynamic) at 0, 1, 4, 8, 12, and 24 hours postoperatively.All patients will use patient‐controlled analgesia (PCA) without a basal infusion. ThePCA device will be set to deliver 1 mg of morphine (0.2 mg/mL concentration) with a10‐minute lockout interval. Patients will be instructed to press the PCA button when VAS≥4. Intravenous paracetamol will be administered every 8 hours.Rescue analgesia with intravenous tramadol (1 mg/kg) will be provided if VAS scoresremain ≥4. The total amounts of opioids, NSAIDs, and other analgesics will be recorded.Postoperative Recovery Quality Postoperative recovery will be assessed using the 15‐itemQuality of Recovery‐15 (QoR‐15) questionnaire, which evaluates five domains: pain,physical comfort, physical independence, psychological support, and emotional state.Patient and Surgeon Satisfaction Satisfaction will be evaluated using a 5‐point Likertscale, where 1 = not satisfied and 5 = very satisfied, based on verbal feedback from boththe patient and the surgeon.Nausea and Vomiting: Nausea and vomiting will be scored using a 4‐point scale:0 = none 1. = mild 2. = moderate 3. = severePotential Complications: Any complications associated with the block or the surgicalprocedure (e.g., hematoma, pneumothorax, local anesthetic systemic toxicity, vascularpuncture, or infection) will be recorded.