(1) The acupuncture needle should not be inserted deeply at PC6 in order to minimise the risk of trauma (2) It seemed likely that various kinds of noninvasive stimulation at PC6 may be similarly effective as needling (3) Careful insertion of the needle with respect to patients’ sensations and better anatomical knowledge of the forearm can help to prevent unexpected needle penetration of the median nerve or persistent median artery
(1) No gender difference (2) The mean dangerous depth for perpendicular insertion was 60.60 mm for SI14 and 55.93 mm for GV14. (3) Suggested depth for perpendicular needling of SI14 and GV14 was within 42 mm in adult
(1) The needle not only easily injuried the upper pleural cavity but also damaged the big blood vessel, the vagus nerve in the mediastinum and the cervical root (2) The safety depth of ST11 ranged 23.7–52.8 mm
(1) No gender or side difference (2) The mean dangerous depth of male was 34.97 mm and female 31.41 mm (3) The depth for perpendicular needling of SI12 is within 22.50 mm
Gender, angles of needle insertion (15, 20, 25, 30, and 40 degrees)
(1) The mean dangerous depth for perpendicular insertion was 49.51 mm of BL12 and 44.88 mm of BL13 (2) It was safe for oblique insertion toward the medial of chest in an angle exceeding 20 degrees (3) No gender difference
(1) The mean depth between the skin and the anterior ethmoidal artery was mm, with an angle of degrees (2) The depth from the skin to the optic nerve tunnel frontal point was mm (3) Needling depth should not exceed 30.36 mm (70% of measured depth) to avoid injury of the optic nerve
(1) Risk of pleural injury may existed when inserting needle perpendicularly in these points (2) Divergence existed in observed needling depths such as 22.5–61.3 mm for ST12
(1) No side difference (2) Depths from in vivo CT images were greater than ones from cadavers (3) Safe depth should be less than 70% of dangerous depth
Rohrer index: <1.2, 1.2–1.5, and >1.5, side, and needling angles
(1) No side difference (2) Depths from in vivo CT images were greater than ones from cadavers (3) Safe depth should be less than 70% of dangerous depth (4) Safe needling angle should be 10 degrees more than dangerous angle
(1) Safe depth should be less than 70% of dangerous depth (2) Needling angles were suggested such as 65 degrees rather than perpendicular insertion for points in the bladder meridian
(1) The dangerous depth of most abdominal points were similar and within 11–17 mm (2) KI11 had the greatest depth up to 25 mm (to the urinary bladder) but with divergence in standard error
(1) Safe depth (from skin to tibial nerve): 15 mm for left side and 16 mm for right side, less than the depth from current used textbook (2) Depth from skin to deep vein: 35 mm
(1) No side difference in dangerous depth except BL17, BL18 for male and BL17 for female (2) Points of bladder meridian closer to the spine had greater depths. Divergence existed between points (3) There was no gender/side difference
(1) The average dangerous depths of 23 chest acupoints were obtained. KI27 had the greatest dangerous depth up to 26 mm. Others ranged from 11.87 to 17.64 mm (2) Divergence existed between points (3) There was no gender/side difference (4) Safe depth should be less than 70% of dangerous depth
80 cadavers (including 30 newborns) and 240 adults for safety depth; 300 real subjects for de-qi depth
All back bladder meridian points and chest points
Gender, Tong Shen Cun, BL, BW (normal, over- and underweight) DQ, and AW
(1) Depths were deeper as compared to ancient writings. The depths highly correlated with body thickness and Tong Shen Cun (2) De-qi depth was related to therapeutic effect (3) De-qi depths of chest points were greater in females but not in back points
(1) The safe depths (80% of the measured depth) were GV16: 40.08 mm, GV15: 38.10 mm, GB20: 39.77 mm, and BL1: 34.25 mm (2) No gender or side difference