Ultrasound-Guided Midpoint Transverse Process to Pleura Block Versus Erector Spinae Plane Block for Postoperative Analgesia in Patients Undergoing Open Renal Surgery :A Randomized Comparative Study.

This prospective, randomized, comparative,clinical study will be conducted to compare the analgesic efficacy of ultrasound-guided midpoint transverse process to pleura (MTP) block and erector spinae plane (ESP) block in patients undergoing elective open renal surgery under general anesthesia.

A total of 50 patients of either sex, aged 18-65 years, with American Society of Anesthesiologists (ASA) physical status I-II and body mass index (BMI) of 20-35 kg/m², scheduled for elective open renal surgery through a subcostal incision, will be enrolled. The study will be conducted at Minia University after approval by the Institutional Ethical Committee and obtaining written informed consent from all participants.

Eligible patients will be randomly allocated in a 1:1 ratio into two equal groups, with 25 patients in each group, using a computer-generated randomization sequence with concealed allocation. Group I will be assigned to receive an ultrasound-guided MTP block, while Group II will be assigned to receive an ultrasound-guided ESP block.

Standardized general anesthesia will be administered to all patients. Anesthesia will be induced with intravenous propofol (2-2.5 mg/kg), fentanyl (1-2 µg/kg), and atracurium (0.5 mg/kg). Anesthesia will be maintained with 1-1.5 MAC isoflurane in an oxygen/air mixture, with additional doses of atracurium administered as required. Ventilation will be adjusted to maintain an end-tidal carbon dioxide level of 30-35 mmHg.

Additional intraoperative fentanyl (1 µg/kg) will be administered incrementally according to predefined hemodynamic criteria, specifically an increase in heart rate or mean arterial blood pressure of more than 20% from baseline.

The assigned regional block will be performed after induction of general anesthesia and before surgical incision, with the patient positioned in the lateral decubitus position and the operative side uppermost. All blocks will be performed under ultrasound guidance at the T9 vertebral level using 30 mL of 0.25% bupivacaine.

For the MTP group, a high-frequency linear ultrasound probe will be placed in a longitudinal parasagittal orientation approximately 2-3 cm lateral to the midline at the T9 level. The transverse process and pleura will be identified. Using an in-plane technique, a 22-gauge echogenic needle will be advanced in a cranial-to-caudal direction until the needle tip is positioned midway between the posterior aspect of the transverse process and the pleura. Following negative aspiration and confirmation of appropriate needle placement by hydrodissection, 30 mL of 0.25% bupivacaine will be injected incrementally under continuous ultrasound visualization.

For the ESP group, the T9 transverse process will be identified using a high-frequency linear ultrasound probe placed approximately 2-3 cm lateral to the midline in a longitudinal parasagittal orientation. The trapezius, rhomboid major, and erector spinae muscles will be identified. Using an in-plane technique, a 22-gauge echogenic needle will be advanced in a cranial-to-caudal direction until the needle tip reaches the interfascial plane deep to the erector spinae muscle and superficial to the transverse process. Following negative aspiration and hydrodissection, 30 mL of 0.25% bupivacaine will be injected incrementally under continuous ultrasound visualization.

At the end of surgery, residual neuromuscular blockade will be reversed with atropine (0.02 mg/kg) and neostigmine (0.04 mg/kg), followed by tracheal extubation. Patients will subsequently be transferred to the post-anesthesia care unit and then to the ward after achievement of a modified Aldrete score of at least 9.

A standardized multimodal analgesic regimen will be administered to all patients. Intravenous paracetamol 1 g will be administered at the end of surgery and subsequently every 6 hours. Intravenous ketorolac 30 mg will be administered every 8 hours during the first postoperative day. Intravenous nalbuphine will be administered as rescue analgesia when the postoperative NRS pain score is ≥4.

The primary outcome will be total postoperative opioid consumption, expressed as intravenous nalbuphine consumption in milligrams during the first 24 postoperative hours.

Secondary outcomes will include intraoperative fentanyl consumption, time to first rescue analgesic request, postoperative pain scores at rest and during movement, hemodynamic parameters, patient satisfaction with pain relief, duration of hospital stay, and the incidence of perioperative complications.

Pain intensity will be assessed using the Numeric Rating Scale (NRS), ranging from 0 to 10, where 0 represents no pain and 10 represents the worst imaginable pain. Hemodynamic parameters, including heart rate, oxygen saturation, systolic blood pressure, diastolic blood pressure, and mean arterial pressure, will be recorded at predefined intraoperative and postoperative time points.

Patient satisfaction with postoperative pain management will be assessed using a 5-point Likert scale.

Perioperative complications will be recorded, including postoperative nausea and vomiting, hypotension, bradycardia, tachycardia, respiratory depression, vascular puncture, pneumothorax, allergic reactions, and signs of local anesthetic systemic toxicity.

If an NRS score of ≥4 is recorded during the first postoperative hour, block failure will be considered according to the study protocol. Rescue nalbuphine will be administered, and the patient will be excluded from the study.

The study will be conducted over a period of one year. The collected data will be analyzed statistically to compare the postoperative analgesic outcomes between the MTP and ESP block groups.