Postoperative Analgesic Effects of Ultrasound-guided Retro-superior Costotransverse Ligament Space Block After Video-assisted Thoracoscopic Surgery: a Prospective Randomized Controlled Trial

After siged the informed consent form, 130 patients who chosed to undergo thoracoscopic radical resection of lung cancer were randomly divided into two groups: the retro-SCTLB group (Group R, 65 patients) and the TPVB group (Group T, 65 patients).ultrasound-guided retro-SCTLB or TPVB was performed 15min before general anesthesia.

Ultrasound-guided retro-SCTLB method: Using an ultrasound low-frequency convex array probe (3-5 MHZ, Sonosite, USA), the probe was placed parallel to the spine 2-3cm outside the spinous process of the fifth thoracic vertebra, on the surface of the transverse process tip. First, the probe was placed above the rib and costo-transverse process joint and observed from the inside out to clearly show the spinous process, lamina, transverse process and rib. Then, the probe was gently moved towards the caudal side. Until the sound shadows of the ribs and transverse processes disappear and inferior articular processes appear on the medial side, and when high-echo superior ligaments of the costal transverse processes appear behind the paravertebral space and anterolateral of the inferior articular processes, then gently rotate the outer edge of the probe towards the caudal side and a low-echo area can be seen behind the superior ligaments of the costal transverse processes, which is the target area. Then, using a long oblique plane puncture needle, with the in-plane technique, insert the needle from the outer side of the probe. When the needle tip reaches the target area, use the water separation technique to inject 2ml of normal saline to confirm the needle tip position, then inject 20ml of 0.375% ropivacaine; Ultrasound-guided TPVB: Using an ultrasound low-frequency convex array probe (3-5 MHZ, Sonosite, USA), the probe is placed perpendicularly to the spine at the fifth thoracic vertebra on the midline of the trunk. First, the spinous process is identified, and then the ultrasound probe is gradually moved towards the surgical side. Structures such as the transverse process, pleura, and intercostal intima are visible. At this point, the ultrasound probe is moved parallel to the caudal side. The area between the parietal pleura, intercostal endometrium and transverse process is the target area for injection. Then, using a short inclined plane puncture needle, using the in-plane technique, the needle is inserted from the outside of the probe. When the needle tip reaches the target position, 2ml of normal saline is injected using the water separation technique to confirm the needle tip position. Then 20ml of 0.375% ropivacaine is injected； General anesthesia was then performed.General anesthesia was performed as follows: After the patient enters the operating room, routine ECG monitoring was performed, and invasive arterial blood pressure was monitored by radial artery puncture and catheterization. General anesthesia was induced with hydrocortisone 100mg, midazolam 0.5mg/kg, ciprofol 0.4mg/kg, sufentanil 0.4ug/kg, vecuronium 0.1mg/kg, and then a double-lumen bronchial tube was inserted under a videro laryngoscope and mechanically ventilated (tidal volume: 6ml/kg, PEEP: 3-5 cm H2O). Anesthesia was maintained with ciprofol (0.6-1mg.kg.h-1), remifentanil (0.12-0.2ug.kg.min-1) ,micuronium (0.2mg.kg.h-1), with BIS monitoring of anesthesia depth, maintaining the BIS value between 40 and 60. Intraoperative hemodynamics was maintained within 30% of baseline. Dexketoprofen trometamol injection 50mg was given intravenously for analgesia and tropisetron 4mg was given to prevent nausea and vomiting when there were no contraindications during the operation. The fluid infusion is limited to 6ml/kg/h. sufentanil 0.1ug/kg was administered intravenously 10min before the end of the procedure. At the end of the operation, the patient was transferred to PACU with an endotracheal tube. After neuromuscular blocking antagonism, the tracheal tube was extubated.

NRS was used to evaluate the pain scores at rest and during movement at 1, 3, 6, 12 , 24 and 48h after operation by a nurse who was unaware of the grouping. sufentanil 150μg and tropisetron 6mg which were diluted to 250ml were used for patient-controlled intravenous analgesia after operation. The parameters of analgesia pump were set as background dose 0.5 ml/h, bolus 5ml, lockout time 8min. If the NRS score was ≥ 4, 1 mg of oxycodone was administered intravenously for rescue analgesia. The NRS pain score uses a continuous numerical scale from 0 to 10, and the patient selects the most representative number based on their own pain intensity: 0 points (no pain), 1-3 points (mild pain), 4-6 points (moderate pain), 7-10 points (severe pain).