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

Table 2

Summary of researches using in vivo evaluation methods in real subjects.

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
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
Streitberger et al. 2007 [25]	50 patients receiving acupuncture including PC6 bilaterally (97 wrists)	PC6	Nerve penetrated or contacted	(1) Association between nerve contact and de-qi was discussed. De-qi was elicited in 85 cases. No association between the number of nerve contacts and de-qi was found; (2) The mean distance from the needle tip to the nerve was 1.8 mm (standard deviation 2.2; range 0–11.3). Nerve contacts were recorded in 52 cases, in 14 of which the nerve was penetrated by the needle
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
He et al. 2004 [28]	40 patients of HIVD of C spine	GV14	BL, BW, and AW	(1) Depth ranges 36–75 mm with a mean of 54.6 mm. The safe depth should be within 36 mm; (2) Measured depth was greater than documents from ancient writings
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
Lin and Wang; 1994 [30]	300 adults	Total of 75 acupoints in head, neck, trunk and lower limb	Gender, BW, and DQ	(1) Discussed de-qi depth but not safe depth; (2) Depth of de-qi was greater in males and people with greater body weight; (3) Depths in neck region were more superficial in trunk and limbs
Lin 1991 [31]	107 adults	Acupoints in the chest and back of subjects receiving acupuncture therapy	Gender, BW (normal, over- and underweight), BL, and DQ	(1) Overweight group had the greatest de-qi depth; (2) Points of female chest had greater depth than male; (3) No correlations between the de-qi depth and electric resistance of each point