2.3. Measurements
nerve injury, hypotension/bradycardia, infection, headache, Respiratory depression
RESPIRATORY DEPRESSION, INFECTION, RESPIRATORY DEPRESSION, COMPLICATIONS, COMPLICATIONS
The patients characters, including age, height, weight, ASA grade, BMI were recorded. Primary outcomes were the success rate of first puncture attempt and average number of punctures. Secondary outcomes were the accuracy of landmark-guided positioning, location time, CSEA operation time, patient-satisfaction score, anesthesia characteristics, and complications of CSEA. The success of first puncture attempt was defined as needle entering skin, without changing puncture site and space, and the needle did not exit skin. In the condition that dural puncture was successful but without outflow of CSF, it is considered that the positioning is inaccurate and the puncture fails. The number of punctures included changing the puncture site or interspace, and reinsertion of the needle from the skin. The accuracy of the intervertebral space location is based on ultrasound-assisted positioning as the gold standard (100%), namely the overall agreement rate of ultrasound-assisted and landmark-guided L3-4 interspace. The time of ultrasound-assisted and landmark-guided positioning starts from touching the skin and ends when the positions of L4-5, L3-4, and L2-3 are marked. CSFA operation time is from the start of lidocaine local anesthesia to the completion of epidural catheterization. Patient satisfaction was scored using a 10-point numerical scale analog scale (1–10), with 10 being very satisfied and 1 being very dissatisfied. Complications of CSEA mainly count the incidence of hypotension/bradycardia, respiratory depression, nerve injury, epidural infection and headache. hypotension/bradycardia was defined as mean arterial pressure (MAP) < 65mm Hg or heart rate (HR) < 50/min. Respiratory depression was defined as the oxygen saturation (SPO