临床上用的许多穿刺针均没有长度标志,在操作过程中甚感不便。如心包积液,超声定位后穿刺时因穿刺针没有长度标志,操作中常怕进针过深刺伤心脏,因情绪紧张导致穿刺失败。又如腰椎穿刺,有时需要改变针头方向,此时要将穿刺针退至皮下重新 Many puncture needles in clinical use have no length markings and are inconvenient in operation. Such as pericardial effusion, ultrasound puncture needle after positioning because there is no length mark, the operation is often afraid of stabbing the heart too deeply into the needle, puncture failure due to emotional stress. Another example is the lumbar puncture, and sometimes need to change the direction of the needle, this time to the needle back to the subcutaneous re-