3.2.1. Historical Origin of Deqi
The theory of deqi (getting qi) and arrival of qi originated from The Yellow Emperor's Inner Canon, which occurred many times in different chapters. It was elucidated more deeply in the following books such as The Classic of Difficult Issues, The Great Compendium of Acupuncture and Moxibustion, The Ode of the Golden Needle, and Song to Elucidate Mysteries. For two thousand years and through the various dynasties, the deqi concept has been central to academic thinking.
The purpose of acupuncture, moxibustion, or other forms of stimulation is the dredging of meridians and regulating of blood and qi. Even though qi does not have a material form, thus cannot be palpated, special importance is given to the regulating of its flow. Because scientific development and theories are being based on physical material, it is thus challenging for people not acquainted with eastern culture to understand such a concept [6]. The arrival of qi and deqi mentioned in The Yellow Emperor's Inner Canon stresses on the feeling of doctors but did not consider patient's sensation as deqi and qi arrival. Mention of patient soreness, numbness, pain, or similar sensations secondary to needle stimulation only appears in the literature at the end of the Qing Dynasty, in The Inner Chapters of Acupuncture and Moxibustion [7] which is to become the rudiment of deqi theory in actual clinical acupuncture today.
3.2.2. Knowledge of Deqi from the Ancient Time to the Present Day
Dr. Cheng [8] considers the arrival of qi and deqi the same. The concept of qi contains the description of both doctors and patients feelings. This view is accepted by most acupuncturists nowadays, such as the description in Chinese acupuncture textbooks: deqi, which is called the “arrival of qi” in ancient time and is called the “needling sensation” nowadays. Deqi means when the needle has been inserted to the desired depth, and manipulation techniques such as lifting and thrusting or twirling and rotating are applied to obtain meridians sensation in the puncturing location” [9]. Needling sensation refers to patient's feeling of soreness, numbness, distension, heaviness, pain, formication, and electrical sensation around the acupoint when the needle is inserted. At the same time, the operator may feel tenseness around the needle” [10]. Dr. Li [11] believes that deqi is a feeling and a reaction between the relevant feelings of patient and doctor, which cannot be considered as deqi when it lacks in either one.
The view of deqi in the ancient medical literature differs from the current acupuncture and moxibustion circle. The ancients described it as the tenseness feeling beneath the operator fingers, while the current acupuncture and moxibustion circle pays more attention to the feeling of patients, which often includes soreness, numbness, distension, and heaviness. Modern researchers [12] divided the patients’ feeling into thirteen types such as pain, soreness, deep oppression, heaviness, distension, chirobrachialgia, numbness, stabbing pain, dull pain, and the feelings of warmth, cold, spasm, and others. Simultaneously, they observe the occurrence of the frequency and intensity of needling sensation shown as follows: sore sensation, oppression sensation, tingling, numbness, and dull pain are more common, while warm sensation and cold sensation are less. Other scholars [13] made a clinical investigation and found that distension, soreness, electrical sensation, and numbness sensation have separately accounted for 94%, 81%, 81%, and 78% of the most common needling sensations, respectively. It is necessary to point out that needling sensation is a new term mentioned by the modern scholars who combined Western medicine knowledge with acupuncture research. It is beneficial for us to intuitively recognize all kinds of acupuncture stimuli. However, in the actual clinical, all kinds of needling sensation had difficulty in guiding the reinforcing and reducing methods. Thus, many physicians put forward their own views on the relationship between the needling sensation and deqi.
3.2.3. Indications of Deqi in Different Perspectives
(1) Besides the Sensation of Soreness, Numbness, Distension, and Heaviness, Other Feelings Can Be Combined. Doctors like Qiu [14], Wang [15], Cheng [16], Shi [17], Zhang [18], Ge [19], Wei [20], and so forth all consider that the needling sensation does not only include soreness, numbness, distension, and heaviness in a local area, but also sensation transmission along the meridians or the arrival of qi at pathological sites. Dr. Liu [21] has pointed out that the slow transmission of sensation such as soreness, numbness, distension, and heaviness differs from the rapid radiating feeling of numbness by stimulating the nerve. Dr. Sun and Dr. Gao [22] believe that if the doctor feels a sunken or tense sensation beneath the needle, it is an indication of deqi. Patient in this case must have a feeling of soreness and distention beneath the needling point, or even an outward spreading feeling. “It can also be observed visually,” says Wei [23], if the skin around the needle appears tense, with a raised or sunken phenomenon, which is also regarded as a form of deqi.
(2) Emphasizing Deqi Lies in the Doctor's Feeling. Dr. Peng [24] believes that some of the patients who do not respond sensitively to the needle insertion or the feeling of sunken or tension beneath the needle are the indication of deqi. Dr. Wang [25] considers that the indications of qi arrival do not only consist of the patient's and the doctor's feeling beneath the needle, but also include the feeling of the doctor's other hand when pressing the skin near the acupoint during acupuncture procedure. Dr. Feng [26] thinks that the present deqi beneath the needle is known by asking the patient, and there is a certain subjective conjecture for the patient's description of the needling sensation. If the qi beneath the needle is mainly recognized by the doctor's feeling, it is more concrete and easier to control the needling. Dr. Chen [27] considers that in some special cases such as coma, emptiness beneath the needle, or noncooperation of the patient that causes the patient to be unable to reflect subjective feelings, the doctor must carefully observe the objective indications such as the sinking and tension beneath the needle and moving up and down of the muscle or limbs. But the most important at this point, which should be taken as the primary evidence, is the efficacy of the treatment. Dr. Zhang [28] thinks that the deqi sensation beneath the needle, as well as the changes and recovery of the pulse after needling, is more important than the patient's sensation. The sensation of deqi beneath the needle of the doctor's hand and the patient's needling sometimes is synchronous but sometimes not.
(3) Other Views. Dr. Jin [29] considers that the sensations of soreness, numbness, heaviness, and distension are just some superficial feelings in the local area which cannot be equally indicated as deqi. Dr. Lai [30] thinks that, nowadays, habitually equalizing deqi to needling sensation, or seeing the strength of needling sensation as deqi and determining the efficacy, is a cognitive mistake. The general feelings of the patient such as soreness, numbness, distension, and heaviness are original, primary, and initiative. Only doctors who identify the pathogenesis can do the manipulation of the reinforcing or reducing methods to achieve the real sense of therapeutic effect of deqi. In addition, the clinical practice has shown that some patients can also get a good efficacy with weak needling sensation or even with no needling sensation at all. In the modern acupuncture, such as wrist-ankle acupuncture, intradermal acupuncture, and abdominal acupuncture, needling sensation is not required for the patients, but many diseases can be cured. Therefore, the concept of latent needling sensation is raised [31], in which, during the acupuncture treatment procedure, the patient does not feel any of the needling sensations such as soreness, numbness, distension, and heaviness, but instead the doctor has a feeling beneath his hand. There is an obvious change of the electric conduction amount that can be detected by the meridian detector, which is proved by responding to the tissue at the acupoint. And the clinical efficacy is considered to be the criterion of the judging of deqi.
Thus, it is obvious that the needling sensation is not the only manifestation of deqi. As we all know, many physiological functions related to meridian phenomenon cannot be directly perceived, such as blood circulation, nerve conduction, muscle discharge, electrical impedance of skin, and hormone secretion. Therefore, it is very normal that the functional activity of the meridian is not directly perceived by people [32]. Another study [33] has shown that the sensitivity of the needling sensation may be related to the individual differences of the secretion levels of endogenous opioid peptides and antiopioid. Dr. Liu and others [34] use a self-developed apparatus to conduct a quantitative analysis of the frequency, speed, time, intensity, and subtle changes of the acupuncture operator to indicate the deqi of acupuncture, which has been all the time reacted to the subjective concept, which can be objectively detected through the mechanical monitoring.