Comparison of nerve blocks applied for preventing muscle contractions in bladder tumor surgeries

Before surgery, 500 mL intravenous 0.9% NaCl is administered to the patients. Heart rate, SpO2, blood pressure, and electrocardiography are monitored in the operating room. Spinal anesthesia is performed using 12.5 mg hyperbaric bupivacaine after insertion of a 25-gauge Quincke spinal needle from L3-4 or L4-5 in the sitting position. Patients are laid in the supine position. Development of sensory block is examined at the T10 level. Required anatomic markings were made on the wall where the tumor was located by the approach to be applied: In the classic method, the puncture point is marked 1.5 cm lateral of tuberculum pubis and 1.5 cm caudal. In the inguinal method, the tuberculum pubis, spina iliaca anterior superior, inguinal ligament, and femoral artery are marked. The puncture entry point is determined as the middle of the tuberculum pubis and femoral artery, and 5-8 cm below the inguinal ligament. Obturator nerve block (ONB) has been performed in surgeries of transurethral resection of bladder tumors (TUR-BT) for the prevention of the development of obturator muscle contraction. Currently, classic and inguinal approaches are frequently being used. Patients are randomized for classic (n=33) and inguinal (n=33) ONBs. Simple randomization is done before study commencement by the Excel (Microsoft, Redmond, WA, USA) random number generation function. Adductor muscle contractions that occurred during the resection are recorded by a urologist who is blinded to the ONB technique. The peripheral nerve stimulator (Pajunk, Melsungen, Germany) is adjusted to 1.5 mA 1 Hz. Insertion is applied from the determined points using an isolated 22-gauge, 100-mm nerve stimulator needle (Pajunk, Melsungen, Germany). The needle is directed cephalad in the inguinal approach. In the classic method, the needle is perpendicularly inserted and slightly withdrawn after reaching the bone; the needle is manipulated 2-4 cm towards the medial. First, suction is performed, and then ten mL 0.25% bupivacaine are administered when an adductor muscle contraction area is detected with the peripheral nerve stimulator between the range of 0.4-0.7 mA. All ONB and TUR-BT procedures are performed by the same anesthesiologists and urologists.