Study endpoints and sample size calculation
MCSL, brachial plexus injury, thyroid injury, hemothorax, pneumothorax, hematoma, nerve damage
HEMOTHORAX, HEMATOMA, PNEUMOTHORAX, COMPLICATIONS
Successful first needle pass without PVWP was the primary outcome of our study. Another needle pass was defined as every needle withdrawal with subsequent redirect and advance, regardless of whether another skin puncture site was selected. Unsuccessful catheterization was identified as the following conditions, including probe placement difficulty (due to the patient’s short neck, there was insufficient space to place the ultrasound probe for ultrasound-guided CVC) results in no space for puncture, multiple attempts (>3 ) or the occurrence of serious complications (artery puncture, hematoma, nerve damage, thyroid injury, pneumothorax, and hemothorax). According to the ultrasound image of the puncture video, the needle tip penetrated the posterior wall of the IJV and was considered PVWP [Expected mechanical complications included: artery puncture (any pulsating blood return to the needle observed during the IJVC procedure or the puncture needle into the artery was observed through the puncture video), external jugular vein (EJV) puncture (the puncture needle into the EJV was observed through the puncture video), PVWP, hematoma (identified by ultrasound) , nerve damage (included vagus, spinal, and brachial plexus injury) , thyroid injury, pneumothorax and hemothorax (identified by chest radiograph).Two evaluators who did not perform the IJVC procedures evaluated the aforementioned outcomes through puncture video. The two evaluators had 5 yrs. of experience in point-of-care ultrasonography and had performed over 300 vascular access procedures under ultrasound guidance. The two judges made their own judgments based on the video. Any disagreements between the two assessors were resolved through discussion. If no consensus was reached, another assessor would be consulted.According to the unpublished data from our pilot research, the rates of first needle pass without PVWP were 95% and 90% for MCSL and OA-IP methods, respectively. Based on the preset non-inferiority margin of -8% in the primary outcome, we utilized PASS software (version 15) to estimate that 86 patients per group would supply 90% power at an α level of 0.025 to compare the MCSL approach with the OA-IP method. Ultimately, we recruited 95 patients in every group to take into account the 10% dropout.