Quadratus Lumborum Block for Anesthesia

Invasive radial arterial blood pressure, heart rate (HR), electrocardiogram (ECG), percutaneous oxygen saturation (SpO₂), and bispectral index (BIS) were routinely monitored after the patients entered to the operating room. Peripheral intravenous access and right central vein access were established. Prior to anesthesia induction, patients in both groups received ultrasound-guided bilateral QLB in the lateral position. Following disinfection of the intervention area, a convex probe (2–5 HZ, Edge, Sonosite, Seattle, USA) was positioned on the anterosuperior iliac crest and moved cranially until the external oblique, internal oblique, and transversus abdominis were identified. Then, the probe was moved posteriorly, and the quadratus lumborum muscle was observed. A 22 gauge × 80 mm needle (Kindly, Shanghai, China) was inserted into the posterior part of the QL muscle. After confirming the optimal site by hydrodissection, group Q was injected with 20 mL of 0.3 % ropivacaine (Naropin, AstraZeneca AB Company, Södertälje, Sweden), and group C was injected with 20 mL of 0.9 % saline on each side. Posterior spread was observed (Fig. 2). After the block, the dermatomes of the sensory block at the 15th minutes were evaluated using pinprick for all subjects.
Fig. 2

Ultrasonographic image of QLB. Arrow shows the direction of needle. EO, external oblique muscle; IO, internal oblique muscle; TA, transversus abdominis; QL, quadratus lumborum; PM, psoas major; ES, erector spinae

After QLB, 0.02–0.03 mg/kg midazolam, 0.3–0.4 µg/kg sufentanil, 1.5–2 mg/kg propofol, and 0.6–0.8 mg/kg rocuronium were administered intravenously for anesthesia induction. Mechanical ventilation was performed by volume-controlled ventilation after intubation to maintain the end-tidal carbon dioxide pressure (PetCO₂) at 30–40 mmHg. Anesthesia was maintained with propofol 0.1–0.2 mg/kg/min and remifentanil 0.2–0.3 µg/kg/min to maintain a BIS of 40–60. Fluid and vasoactive drugs were administered to maintained intraoperative haemodynamics within the appropriate range during surgery by experienced anesthesiologists. Following surgery, 0.15 µg/kg sufentanil and parecoxib 40 mg IV were used for postoperative analgesia. A patient-controlled intravenous analgesia pump with sufentanil was administered to all patients after being transferred to the recovery room.