Methods
’ head, paresthesia, numbness, pain
QUINCKE, PARESTHESIA, DECUBITUS, MUSCULOSKELETAL DISORDERS, SECONDARY, COMPLICATIONS
The present study was conducted with the approval of the China Ethics Committee of Registering Clinical Trials (ChiECRCT-20,180,065), and written informed consent was obtained from all subjects participating in the trial. The trial was registered prior to patient enrollment at Chinese Clinical Trial Registry (NCT: ChiCTR1800016078, Principal investigator: Juan Gu, Date of registration: 09 /05/2018). This study also adheres to the CONSORT guidelines.100-and-8 pregnant women, ASA I-II, undergoing CSEA for cesarean delivery were recruited and provided written informed consent. The exclusion criteria were contraindications for CSEA, and history of spinal surgery or severe anatomical abnormalities of the spine. Computer-generated block randomization was used to randomly allocate the patients to one of three groups in accordance with the height of the operating table. The table height was set with the needle insertion point (the midline of the patient’s body) at the level of the anesthesia provider’s umbilicus for group U, the lowest rib margin for group R, and the xiphoid process in the standing posture for group X.Anesthesia was administered by residents who had each performed neuraxial anesthesia less than 10 times. Exclusion criteria for residents were: body mass index > 30, pregnancy, musculoskeletal disorders, and refusal to participate.Residents completed a 2-month training period for CSEA. After theoretical learning and simulated training, each resident was scheduled to practice CSEA in the obstetric surgery room for 2 days each week. Before initiating CSEA, an anesthesiologist who was not blinded to group allocation adjusted the height of the operating table in accordance with the grouping information contained in sealed opaque envelopes. Patients were placed in the left lateral decubitus position, parallel to the edge of the operating table, with the knees flexed on the abdomen, and the neck flexed. Under supervision of an anesthesiologist, the resident inserted a 17-gauge Quincke epidural needle (YA GUANG, China) orientating patients’ head in the midline at the L3–L4 or L2–L3 interspace. The epidural space was identified using the loss-of-resistance method. After the epidural needle was positioned in the epidural space, a 25-gauge spinal needle was advanced through the epidural needle, dural puncture was verified by visualization of cerebrospinal fluid after removal of the spinal needle stylet, and 10–12.5 mg bupivacaine was administered. A stiff catheter was inserted into the epidural space after the spinal needle was removed. Epidural vein cannulation was verified by the visualization of blood. If the resident could not successfully advance the needle into the epidural space after two attempts, the epidural anesthesia was classified as a failure and the CSEA was administered by the supervising anesthesiologist. If the resident could not successfully insert the spinal needle or the patient reported the onset of paresthesia while the spinal needle was being advanced, the resident could change the direction of spinal needle advancement twice by depressing or lifting the tail of the epidural needle. If the patient still reported abnormal feelings or the spinal needle still could not be successfully inserted, the spinal anesthesia was classified as a failure and the CSEA was administered by the supervising anesthesiologist.The primary outcomes were the rates of successful epidural anesthesia and spinal anesthesia. Complications including paresthesia, which was defined as an abnormal feeling (electrical sensation, numbness, and/or pain) in the patient’s lower extremities while the spinal needle was being advanced, and catheterization of a blood vessel were second outcomes. Other secondary outcomes were the time between puncture initiation and the achievement of successful epidural anesthesia, incidence of needle angle adjustment, and the residents’ table height preferences.A pilot study (10 patients each in groups U and X) was conducted to enable the estimation of an appropriate sample size. The rate of successful CSEA was about 54 and 40%. To detect a difference of 10% in the rate of successful dural puncture after needle entry into the epidural space, 50 patients per group were required to achieve a power level of 80% using a two-tailed test with α = .05. Assuming a dropout rate of 10%, a total of 180 patients were needed to detect a significant difference.