An Exploration of the Needling Depth in Acupuncture: The Safe Needling Depth and the Needling Depth of Clinical Efficacy

Table 3

Summary of researches using CT scan images for measurement of the depths of acupuncture points.

Authors and year	Subjects and sample size	Investigated acupuncture points and their body regions/meridians	Parameters used in comparison and related factors	Results, suggestions, and conclusions
Chen et al. 2009 [32]	204 pediatric patients aged 7–15	12 abdominal acupuncture points CV-3, CV-4, CV-6, CV-10, CV-12, CV-14, KI-12, ST-24, ST-25, SP-15 LV-13, and LV-4	Gender, age, BW, and waist girth	(1) Using the therapeutic depth over safety depth ratio (T/S ratio) as the indicator of therapeutic depth; (2) No significant difference in the T/S ratio between genders; (3) The T/S ratio of these 12 acupuncture points ranged from 0.67 to 0.88 and increased significantly with body weight, age, and waist girth; (4) The therapeutic depth of abdominal acupoints was closer to the safe depth in overweight and older children aged 7 to 15; (5) No significant difference between genders
Groenemeyer et al. 2009 [24]	58 patients with low back pain	BL25, BL26	BMI	(1) An association between de-qi and needle location existed; (2) The distance between BL25 and BL6 to the vertebral line was 3.49±0.58 and 3.32±0.53 cm, respectively; (3) There was a significant correlation between the interscapular distance and the thickness of the soft tissue layer with the BMI at both acupuncture points
Yang et al. 2008 [33]	41 adults	GV16	Rohrer index	(1) The safe needling depth should be less than 75% of the dangerous depth; (2) The safe depths of GV16 were different for persons of different somatotypes ranging 27.73–33.39 mm
Chen et al. 2008 [34]	219 pediatric patients aged 7–15	12 acupoints along the conception vessel (CV): CV-2 to CV-7 and CV-9 to CV-14	Gender, age, BW, and waist girth	(1) The safe depth of 12 acupoints significantly increased with age, body weight, and waist girth in pediatric patients aged 7–15; (2) There were large variations of the 12 points among different age and body weight groups; (3) The safe depths were 1.3–2.1 times deeper in the 12–15-year-old group than in the 7–9-year-old group and 1.7–3 times deeper in overweight children than in underweight children
Chern et al. 2006 [35]	32 adults	BL13	Rohrer index (<1.2, 1.2–1.5, and >1.5), side	(1) Right side points seemed to be deeper, especially in people with Rohrer index <1; (2) Safety depth should be within 75% of the measured distance in each group; that is, 34, 25, and 23 mm
Li et al. 2005 [36]	32 adults	GV14, SI15, GV5, and GV4	Rohrer index: <1.2, 1.2–1.5, and >1.5	The safe depths (75% of dangerous depths) were different for different somatotypes; for example, the needling depth for GV14 was 32.86±3.96 mm for the thin person group and 47.93±5.30 mm for the fat person group
Dong et al. 2004 [26]	32 adults and 10 cadavers	7 points from bladder meridian (2nd side line)	Rohrer index: <1.2, 1.2–1.5, and >1.5, side	(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
Li et al. 2004 [27]	32 adults and 10 cadavers	7 points from bladder meridian (1st side line)	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
Lin 1997 [29]	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
Sheu and Lin; 1992 [37]	120 adults	28 points in the chest from conception vessel, kidney meridian, stomach meridian, pericardium meridian, lung meridian, spleen meridian, and gallbladder meridian	gender, BW (normal, over- and underweight), and BL	(1) Significant differences in chest points within the same sex existed; (2) For different body sizes, statistically significant differences for each point appeared
Lin et al. 1991 [38]	240 adults (120 in each group)	22 points in the back; 28 points in the chest	Gender, BW (normal, over- and underweight), and BL	(1) No gender differences on back loci; (2) Significant differences in each point with different body sizes; (3) Female chest points had greater depths; (4) The results should be more accurate than cadaver study