[Analysis on the temperature-time curve in warm needling manipulation with acupuncture needles of different materials].

Objective: To analyze the characteristics of the temperature-time curve in warm needling manipulation with the acupuncture needles made of copper, silver, gold and stainless steel and explore the applicable temperature range and most suitable needle materials of warm needling manipulation in clinical practice.

Methods: A total of 10 healthy subjects were included. Using the digital thermometer, with different moxibustion dose (1.2 g or 1.5 g, moxa), the temperature was measured at the site where the skin contacts with the needle body during the warm needling manipulation with stainless steel needle, copper needle, gold needle and sliver needle separately. The initial heat pain threshold (the temperature when hot feeling started) and the burning pain threshold (feeling very hot but tolerable) were recorded when using the different needles mentioned above. Through the subject questionnaire, the comfort degree, the heat sensation, the adverse reaction and the acceptability to warm needling manipulation with the different needles were investigated.

Results: During the warm needling manipulation, the initial heat pain threshold was (42.8±2.7) ℃ and the burning pain threshold was (46.7±2.9) ℃. The strongest warm stimulation was presented in the warm needling manipulation with 1.5 g moxa and silver needle and the highest temperature was (55.5±6.3) ℃, followed by (52.9±4.2) ℃ with 1.2 g moxa and silver needle, (46.6±3.7) ℃ with 1.5 g moxa and gold needle, (46.6±1.9) ℃ with 1.5 g moxa and copper needle, (43.1±1.5) ℃ with 1.2 g moxa and copper needle and (41.7±0.9) ℃ with 1.5 g moxa and stainless steel needle. The sequence of the maintaining time of the initial heat pain threshold over 43℃ was 480 s with silver needle and 1.5 moxa, 325 s with silver needle and 1.2 g moxa, 270 s with gold needle and 1.5 g moxa, 185 s with copper needle and 1.5 g moxa, 42 s with copper needle and 1.2 g moxa and 0 s with stainless steel needle and 1.5 g moxa successively. The heat score graded by the subjects to the warm needling manipulation with different needles, from high to low, was presented in the manipulation with 1.5 g moxa and silver needle, 1.2 g moxa and silver needle, 1.5 g moxa and copper needle, 1.5 g moxa and gold needle, 1.2 g moxa and copper needle and 1.5 g moxa and stainless steel needle. The VAS score was different significantly in comparison among the six needles in warm needling manipulation (<0.001). The comfort degree of the subjects in the warm needling manipulation with silver needle and 1.5 g moxa was significantly lower than the warm needling manipulation with the other 5 materials (<0.05). Three subjects complained that the warm needling manipulation with silver needle and 1.5 g moxa was too hot to be tolerable and the most of subjects were willing to accept warm needling manipulation with these 6 materials (acceptability 70.0% to 100.0%). Except blisters presented in 9 subjects after warm needling manipulation with silver needle and 1.5 g moxa, no severe adverse reaction occurred in warm needling manipulation with 6 materials.

Conclusion: In the warm needling manipulation in the human body, the initial heat pain and the burning pain threshold were 43 ℃ and 47 ℃ respectively, which is the applicable temperature range of moxibustion in clinical practice. The warm needling manipulation with silver needle induces a quite strong heat stimulation and the discomfort may be caused when the temperature is exceeded to some threshold. The warm needling manipulation with copper needle generates the onset temperature, without inducing adverse reactions, e.g. discomfort and burning in the subjects.