Acupuncture-assisted anesthesia in surgical procedures: A comprehensive review of operational methods, technical details, ear and body acupoints application

Abstract

Due to its benefits of minimum physiological interference, few complications, and promotion of postoperative recovery, acupuncture-assisted anesthesia (AA), an inventive fusion of modern anesthesiology and traditional Chinese medicine, has been used more frequently in clinical surgical practice. This review systematically summarizes the specific operational techniques and technical details of AA across various surgical procedures. Mechanistically, AA produces analgesia, sedation, and organ protection through modulation of the nervous, endocrine, and immune systems. In terms of operational specifications, auricular points are primarily stimulated via acupressure or needling at Shenmen (TF4) and surgical site-specific reflex zones, while body acupoints including Hegu (LI4), Zusanli (ST36), and Neiguan (PC6) are selected according to local, distant, and empirical principles, combined with standardized electroacupuncture parameters (frequency, intensity, and waveform). Clinical evidence demonstrates that auricular acupuncture reduces intraoperative fentanyl requirement by 15% compared with sham acupuncture. These clinical benefits depend on the standardized implementation of the following practices: Preoperative formulation of individualized acupoint combinations based on surgical type and patient constitution, intraoperative application of 2/100 Hz dense-disperse electroacupuncture at appropriate intensity, and postoperative continuation of auricular acupressure to consolidate analgesic effects and promote gastrointestinal recovery. To give clinicians a standardized, useful reference to enhance the safety and efficacy of AA application and encourage the thorough integration of traditional Chinese medicine and contemporary surgical anesthesia, the present difficulties and future development directions of AA in surgical practice are finally outlined.

Key Words: Acupuncture-assisted anesthesia; Intraoperative analgesia; Electroacupuncture parameters; Neuroendocrine-immune mechanism; Acupoint specificity

Core Tip: Analgesia, sedation, and organ protection are provided during surgery via acupuncture-assisted anesthesia, which combines traditional acupuncture with contemporary anesthesiology. Standardized procedures for body points and auricular points across different surgeries are described in this review, with a focus on surgical site-specific tactics. Acupuncture-assisted anesthesia works by coordinating neuroendocrine-immune control, which includes immunomodulation, vagal reflexes, endogenous opioid release, and peripheral afferent activation. The review also highlights clear clinical benefits, including reduced anesthetic use and fewer complications. However, issues like methodological limitations and non-standardized protocols remain. Future multicenter trials and multi-omics research will help better integrate this approach into modern anesthesia.

INTRODUCTION

General anesthesia (GA) relies heavily on anesthetic drugs, which carry significant risks and side effects. For instance, problems like emergence agitation, postoperative cognitive dysfunction, and postoperative nausea and vomiting might be brought on by anesthetic medications[1-3]. Additionally, surgical trauma itself sets off a significant physiological stress response that includes immunological and neurohormonal cascades. In extreme circumstances, this reaction may develop into systemic inflammatory response syndrome[4]. Strategies that reduce these side effects while preserving anesthetic effectiveness are therefore obviously important from a therapeutic standpoint. Acute and chronic pain are both adequately relieved by acupuncture, providing an empirical foundation for its use with anesthesia to enhance patient outcomes[5].

Acupuncture-assisted anesthesia (AA) combines Western anesthesia and surgical techniques with traditional Chinese acupuncture. Acupoints are chosen based on the surgery site, pattern distinction, or meridian pathways[6]. After the first successful tonsillectomy with AA assistance was carried out in Shanghai in 1958, AA was later used for surgeries like thyroidectomy and pulmonary resection[7]. However, there are significant disadvantages to utilizing acupuncture as the only anesthetic modality, including traction reactions, muscle tension, and partial analgesia, suggesting that it cannot completely replace anesthetic medications[7]. Acupuncture-only anesthesia gave way to acupuncture-assisted pharmaceutical anesthesia as a result. Such aided protocols improve intraoperative stability and decrease the need for anesthesia, according to an increasing amount of clinical evidence[8]. Thus, AA provides a new clinical approach in the field of anesthesiology by improving patients’ ability to recuperate.

Although AA is being used more frequently in clinical settings, a standard operating procedure has not yet been developed. An evidence-based systematic review is urgently needed because acupoint selection, stimulation parameters, and technical methods vary significantly among surgery categories. To fill this gap, the current review synthesizes the contemporary biological mechanisms that explain acupoint specificity and methodically compiles the operative techniques and technical details of AA across various surgical procedures, with a focus on the application standards of auricular and body acupoints. Our goal is to give medical professionals a standardized, useful resource to help standardize AA uptake and advancement. The overall framework of this review is shown in Figure 1.

Figure 1 Neuro-endocrine-immune network multi-target integration. This figure illustrates the key components of acupuncture anesthesia as a perioperative integrative technique. Left panel (mechanism): Acupuncture anesthesia exerts its effects through a neural-endocrine-immune regulatory network. The central nervous system (brain and spinal cord), endocrine system (adrenal glands), and immune system (macrophages) interact to achieve analgesia, sedation, and organ protection. Middle panel (operation specifications): Auricular acupoints, particularly Shenmen (TF4) located in the triangular fossa, and visceral reflex zones are stimulated using ear press seeds. Body acupoints, exemplified by Zusanli (ST36), are stimulated with electroacupuncture using dense-disperse wave parameters. Right panel (applications): Acupuncture anesthesia is tailored to six surgical categories: Craniocerebral (brain), cardiothoracic (thorax), abdominal, orthopedic (bone), thyroid, and anorectal (lower intestine) surgeries, with acupoint selection and stimulation methods optimized according to surgical site. AA: Acupuncture-assisted anesthesia.

MECHANISMS OF AA: AN INTEGRATED MULTILEVEL INTEGRATIVE MODEL

Peripheral initiation: From acupoint activation to afferent signals

AA’s mechanism starts at the peripheral acupoints. Both non-neuronal and neuronal components are activated when local tissues are physically or electrically stimulated by needling or electroacupuncture. Since mast cell stabilizers lessen the effects of acupuncture, the activation of mast cells in the acupoint region is essential for producing acupuncture signals when they proliferate and degranulate[9]. Concurrently, needling stimulates A-fiber afferents, which send action potentials to the spinal cord through particular peripheral nerves, such as the ulnar nerve[10]. The strength and mode of acupuncture stimulation are encoded in a single peripheral signal that is formed by the convergence of these two events, which are not independent[11]. As a result, the peripheral initiation of AA is a coordinated process that depends on both mast cells and neurons.

Central integration: Convergence, modulation, and network processing

Afferent signals undergo initial integration when they converge with nociceptive inputs in the spinal dorsal horn. Signals from the spinal cord ascend primarily through the ventrolateral funiculus to several supraspinal centers, such as the arcuate nucleus, medullary raphe nuclei (such as the nucleus raphe magnus), hypothalamus (such as the paraventricular nucleus), and periaqueductal gray (PAG)[12]. At this brain level, the release of endogenous opioid peptides (such as enkephalins and β-endorphin) is a key mechanism of AA. Classic findings demonstrating the reversal of acupuncture-induced analgesia by the opioid receptor antagonist naloxone support this opioidergic connection[13,14]. Acupuncture simultaneously modifies the hypothalamic-pituitary-adrenal (HPA) axis by boosting the release of oxytocin to reduce anxiety and inhibiting corticotropin-releasing factor, which reduces perioperative stress responses[15,16]. Rather than being separate modules, these core actions are incorporated into a diffuse brain network. The PAG, hypothalamus, medullary raphe nuclei, and autonomic pathways (such as sympathetic and vagal nerves) are all part of this network, which is functionally connected. Specifically, the PAG-medullary raphe-spinal dorsal horn route is an important descending inhibitory system that serves as the foundation for coordinated systemic effector responses and descending control[12,17].

Efferent pathways: Autonomic, endocrine, and immunological outputs

There are two main efferent routes that carry the output of the combined central signals. First, autonomic pathways: Acupuncture triggers vagal parasympathetic reflexes and sympathetic outflow, which raises plasma adrenaline levels[18]. Acupuncture modulates the biliary tract’s Oddi sphincter and speeds up the healing of postoperative ileus, among other visceral functions, through the vagus nerve[15,19]. Second, neuroendocrine and immunological pathways: Acupuncture affects circulating stress hormones and cytokines through the sympatho-adrenomedullary system and the HPA axis. Crucially, vagal activation initiates the cholinergic anti-inflammatory pathway, which helps to protect organs and reduce systemic inflammation[15,20-22]. Overlapping core networks are expected to co-activate these pathways, indicating a coordinated rather than autonomous operation.

Integrated effector outcomes: Analgesia, sedation, and organ protection as the result of the coordinated multilevel mechanism

Analgesia, sedation, and organ protection are not distinct “additional benefits” of AA; rather, they are direct results of the integrated multilevel network mentioned above. Descending inhibition, which inhibits spinal nociceptive transmission, is the cause of analgesia; in clinical settings, this mechanism lowers the need for opioids[20,23], and research on animals confirms that certain acupoint stimulation results in clear analgesic benefits[24]. Oxytocin release and HPA regulation provide sedation and anti-stress effects[16]. The anti-inflammatory, anti-apoptotic, and mitochondrial-protective effects mediated by vagal and sympathetic efferents are reflected in organ protection: In cardiac surgery, electroacupuncture assistance reduces myocardial injury and systemic inflammation, shortens mechanical ventilation, and shortens intensive care unit stay[20,23]; in the gastrointestinal tract, it promotes functional recovery and reduces postoperative ileus[15,25]; and in the brain, it prevents postoperative cognitive dysfunction by preventing neuroinflammation, mitochondrial damage, and apoptosis[26-29]. The entire mechanism of AA as a holistic anesthetic modality is derived from the same neuroendocrine-immune network, which produces these effector consequences simultaneously[30]. The central nervous system uses a negative feedback loop to detect peripheral effector signals (such as decreased inflammation) and modify descending outputs correspondingly[31]. However, its interactions with other anesthetic agents, including propofol, sevoflurane, and muscle relaxants, remain largely unexplored. The above multilevel integrative mechanisms are summarized in Figure 2.

Figure 2 Multilevel integrative mechanisms of acupuncture-assisted anesthesia. The multilayer integrative mechanisms of acupuncture-assisted anesthesia, including peripheral initiation, cerebral integration, and systemic effector outputs, are illustrated in this graphic. By activating local mast cells and A-fiber afferents at acupoints, needling stimulation transmits signals to the central nervous system. Endogenous opioid release (which naloxone reverses), oxytocin production, and regulation of the hypothalamic-pituitary-adrenal axis via corticotropin-releasing factor inhibition are all components of central integration. Sympathetic and vagal efferents carry out autonomic control, which permits bidirectional regulation of visceral processes like Oddi sphincter activity and the reduction of postoperative ileus. Myocardial protection, anti-inflammatory, neuroinhibitory, and mitochondrial preservation are examples of downstream effects. The neuroendocrine-immune network that these processes collectively form is what gives acupuncture its sedative, analgesic, and organ-protective effects. CRF: Corticotropin-releasing factor.

APPLICATION STANDARDS OF AURICULAR POINTS

The principle of reflection and projection of auricular points

The fundamental theory behind auricular point therapy is the corresponding association between the auricle and other bodily organs. According to the “inverted fetus” paradigm, the head is represented by the earlobe, the upper limbs by the scapha, the lower limbs and trunk by the antihelix, and the internal organs by the concha[32]. However, the key mechanism underlying AA is the vagal afferent pathway. The auricular branch of the vagus nerve (ABVN) innervates the concha region and projects directly to the nucleus tractus solitarius[33], forming a neuroanatomical substrate for vagal regulation of pain and autonomic functions during surgery[33,34]. By contrast, the helix and scapha are innervated by cervical spinal nerves (e.g., the great auricular nerve) and lack such direct central connections[35]. Clinical studies have demonstrated that stimulation of ABVN-innervated areas (e.g., concha) produces significant analgesic effects in the context of anesthesia, whereas stimulation of spinal nerve-innervated areas (e.g., helix) does not[33,35]. Beyond its well-established roles in analgesia and autonomic regulation, activation of the ABVN-innervated auricular region (e.g., concha) triggers the cholinergic anti-inflammatory pathway, as demonstrated in a recent lipopolysaccharide-induced acute otitis media model. In this study, transcutaneous auricular vagus nerve stimulation significantly suppressed nuclear factor kappa B activation and reduced local and systemic pro-inflammatory cytokines (tumor necrosis factor alpha [TNF-α], interleukin 1 beta [IL-1β], IL-6) via α7 nicotinic acetylcholine receptor-dependent signaling, without compromising upstream Toll-like receptor 4/myeloid differentiation primary response 88 innate immune recognition[36]. Accordingly, the selection of auricular points for AA is largely empirical, often combining core analgesic points such as Shenmen (TF4) with reflex zones corresponding to the surgical site[32]. Although somatotopic mapping and the inverted fetus theory provide a historical framework[32,37], their detailed description (e.g., finger, wrist, elbow, or visceral organ projections) is not essential for understanding the mechanisms of AA. Instead, the vagal afferent pathway and empirical point selection based on clinical efficacy should be emphasized as the most relevant aspects for AA.

Commonly used auricular points

In the practice of auricular anesthesia and perioperative analgesia, Shenmen is the most widely used core acupoint. Shenmen is located at the posterior upper edge of the triangular fossa, and its nerve innervation mainly originates from the mixed distribution area of the ABVN and the greater auricular nerve[37]. In clinical anesthesia-related research, Shenmen has almost become the standard choice for auricular pain relief in various surgeries. Shah et al[38] described the Battlefield Acupuncture protocol, which includes Shenmen along with Cingulate Gyrus, Thalamus, Omega 2, and Point Zero, with indwelling needles placed under GA.

Apart from Shenmen, the other four acupoints in the Battlefield Acupuncture protocol - Cingulate Gyrus, Thalamus, Omega 2, and Point Zero - have also been investigated for their analgesic properties. The cingulate gyrus acupoint is located at the beginning of the foot above the helix, and the thalamus acupoint is on the inner side of the tragus. Both are involved in the central processing of pain signals. Functional magnetic resonance imaging studies have confirmed that stimulating these two acupoints can activate brain regions related to pain regulation[38]. The Omega-2 acupoint is located between the starting part of the helix foot and the lower part of the opposite helix foot and is believed to have the effect of reducing physical stress. The zero point is located at the base of the helix foot and serves as an anatomical reference point for auricular point positioning. It also has the function of regulating autonomic nerve function[38]. No adverse reactions related to acupuncture were reported in the trial[38]. Wetzel et al[39] investigated the effect of auricular acupuncture on intraoperative fentanyl requirement during total hip arthroplasty. In a randomized, patient- and anesthesiologist-blinded controlled trial, 120 patients scheduled for total hip arthroplasty received indwelling press needles either at three specific auricular points ipsilateral to the surgery site (MA-AH4 [Hip], MA-TF1 [Shenmen], and MA-IC1 [Lung]) or at three non-acupoints on the ear helix as a sham procedure. The needles were placed on the evening before surgery and removed on the day after surgery. Auricular acupuncture reduced intraoperative fentanyl requirement by 15% compared with sham acupuncture (4.6 ± 1.1 μg/kg vs 5.2 ± 1.3 μg/kg; P = 0.008). This finding aligns with earlier evidence that auricular acupuncture can decrease volatile anesthetic requirements[40] and that transcutaneous electrical stimulation of an auricular point reduces desflurane consumption[41]. Together, these studies support a modest but significant intraoperative opioidsparing effect of auricular acupuncture.

More recently, after reanalysis of 17 randomized controlled trials, it was found that 15 commonly used auricular points for analgesia were located in the innervation area or mixed innervation area of the ABVN, while the false acupuncture control points were mainly distributed in the innervation area of the cervical nerve such as the helix. This neuroanatomical distribution feature provides a mechanism explanation for the analgesic effect of auricular points - stimulating the ABVN can activate the nucleus solitarius. This further regulates autonomic nerve function and activates the endogenous opioid system[42]. In clinical research, He et al[43] and Zhou et al[44] both adopted a pseudo-control design to set non-acupoint points in the auricular helix area, confirming that specific auricular points had better analgesic effects compared to non-acupoint points; Shah et al[38] pointed out through functional magnetic resonance imaging evidence that stimulation of the cingulate gyrus and thalamus points can activate brain regions related to pain signal processing, providing imaging support for the neurophysiological basis of auricular point selection. These findings collectively suggest that the clinical selection of auricular point stimulation methods should give priority to acupoints located in the area innervated by the ABVN (such as the conchae area) to maximize the neuroregulatory effect.

Operating techniques

Auricular acupressure is a commonly used stimulation method in AA. It is widely applied in clinical practice due to its advantages such as non-invasiveness, simplicity, and high patient acceptance. In pediatric patients undergoing hernia surgery, Wang Bu Liu Xing seed patches were applied to the Shenmen, sympathetic, and subcortical acupoints. The pressing was performed by nurses using their index finger and thumb on the same side of the ear, each session lasting 2 minutes, repeated every 30 minutes, with daily pressing periods from 8:00-11:00 and 14:00–17:00 for 3 consecutive days[45]. Zhou et al[44] adopted a simplified protocol in patients after lower limb fracture surgery, selecting the sympathetic, subcortical, Shenmen, and corresponding auricular points at the surgical site. Patients pressed each point 20 times per session, 4 times daily for 3 consecutive days. Yeh et al[46] used a protocol of 3 minutes per point, 4 times daily for 72 hours in patients after lumbar spine surgery, selecting six points: Shenmen, occipital, lumbosacral vertebrae, stomach, cardia, and endocrine.

Auricular acupuncture, especially the indwelling needle technique, provides another effective method for continuous auricular point stimulation. In adult tonsillectomy, the “Battlefield Acupuncture” protocol described by Shah et al[38] implanted ASP semi-permanent gold needles at five sites (cingulate gyrus, thalamus, Omega-2, point zero, and Shenmen) under GA. The indwelling needles were expected to extrude spontaneously within 3 to 7 days after surgery[38].

Synergistic effects may exist among different stimulation methods. Fu et al[45] adopted a combination of electroacupuncture and auricular acupressure in children with hernia. Electroacupuncture was applied at Sanyinjiao and Zusanli points with a frequency of 10-15 Hz, and needles were retained for 20 minutes, three times per day[45].

In summary, auricular points, particularly those innervated by the ABVN in the concha region, provide a unique portal for global, autonomic nervous system-centered regulation. In contrast to this global vagal mechanism, the application of body acupoints is predominantly based on somatotopic innervation and segmental spinal reflexes. Consequently, these two categories of acupoints are complementary and synergistic. Auricular points offer a “remote, systemic” regulatory backdrop, while body acupoints enable “local, targeted” modulation of pain and organ function at the spinal segmental level. The following section details the application specifications for body acupoints, grounded in this complementary framework.

Safety considerations of auricular point stimulation

Beyond technical details of stimulation methods and parameters, the safety profile of auricular point manipulation warrants careful consideration. Tan[47] conducted the first systematic review of adverse events associated with auricular therapy, encompassing 43 studies with 3396 participants across multiple modalities including acupuncture, acupressure, electroacupuncture, and bloodletting. The review found that the most frequently reported events were local tenderness, minor bleeding, dizziness, nausea (for acupuncture), and skin irritation (for acupressure), with the vast majority classified as transient and mild; no serious adverse events were documented. However, the authors cautioned that most included trials did not prespecify safety outcomes or adequately describe data collection methods for harms, raising the possibility of underreporting and limiting causal attribution. Additionally, in a double-blinded sham-controlled trial of 74 patients, de Oliveira Rodrigues[48] reported that mild pain at the application site (94%), local itching (31%), and punctate bleeding (9%) were the most common adverse effects; local inflammation occurred in one case and resolved with treatment. No significant difference in adverse effect rates was observed between the verum and sham groups, and no severe events were reported. Taken together, these findings support the relative safety of auricular point stimulation, while underscoring the need for aseptic technique, caution in patients with bleeding disorders or metal allergies, and monitoring of indwelling needles for potential migration or breakage.

APPLICATION SPECIFICATIONS FOR BODY ACUPOINTS

Principle of acupoint selection

Auricular analgesia mainly exerts its regulatory effects relying on the mechanism of ABVN auriculo-vagal reflex. By contrast, the effects of body acupoints are based on the core neuroanatomical foundation of somatic nerve-spinal segmental projection and central integration. Stimulation can activate segmental reflexes and higher central regulation through the spinal nerve afferent pathway, providing modern neurobiological evidence for local acupoint selection, distal acupoint selection, and empirical acupoint selection[49].

The selection of body acupoints for AA must adhere to the principle combining local acupoint selection, distal acupoint selection, and empirical acupoint selection, so as to achieve a synergistic effect of precise analgesia and viscera protection. Local acupoint selection provides the basic analgesic effect for AA. Its neuroanatomical basis lies in homosegmental spinal innervation and segmental pain modulation. By selecting meridion-related acupoints or Ashi points adjacent to the surgical site, it directly blocks the conduction of local pain signals to the central nervous system[50]. For example, during the perioperative period of abdominal surgery, acupoints such as Tianshu (ST25) and ST36 are selected to mainly promote the recovery of postoperative gastrointestinal function and relieve postoperative abdominal pain[51]. Distal acupoint selection is an extension and collaboration of local acupoint selection. Based on the theory of meridians, it selects acupoints at distant sites connected to the surgical site via meridians. Its neuroanatomical foundation is intersegmental neural projection and supraspinal central integration. Through meridian conduction sensation, it not only assists in strengthening the analgesic effect but also regulates autonomic nerves and protects viscera and organs, avoiding the limitations of local analgesia. This is one of the key characteristics that distinguish AA from drug anesthesia. In the early stage after laparoscopic surgery, abdominal acupoints (such as ST25) may carry risks such as residual pneumoperitoneum, intestinal adhesion, inaccurate positioning due to local edema, and puncture risks. Such risks reduce the safety and effectiveness of local acupoint selection. Therefore, research teams prioritize limb distal acupoints, such as ST36, PC6, and Shangjuxu (ST37), in laparoscopic surgery for gastric cancer[52]. Empirical acupoint selection is a clinical optimization and supplement to the first two methods, derived from the verification and summary of long-term clinical practice. Its effects are mostly associated with the dense distribution of nerve plexuses and multisystem neural reflex pathways. It is used to relieve adverse reactions such as intraoperative vomiting, improve postoperative functional recovery, and assist in analgesia. Among them, the combination of ST36 and PC6 is the most representative and efficient acupoint combination in clinical practice. According to the surgical type and main complications, adjustments can be made within the “common acupoint spectrum” to further improve anesthesia safety and patient comfort[53,54]. The synergistic effect of local, distal, and empirical acupoint selection ensures the safe and efficient exertion of AA in surgical operations.

Commonly used body points

In clinical and basic research on body acupoint acupuncture intervention, LI4, ST36, and PC6 are the most widely used core acupoints. LI4, the Yuan-Source point of the Hand-Yangming Large Intestine Meridian, is located between the 1^st and 2^nd metacarpal bones on the back of the hand, approximately at the midpoint of the radial side of the 2^nd metacarpal bone. The core efficacy of LI4 in surgical AA is analgesia and sedation, and it is often used as a key acupoint, especially in head and neck surgeries. Acupuncture at LI4 accelerates the central release of opioid-like neurotransmitters such as β-endorphin into the blood, exerting an endogenous analgesic effect[55]. In addition, studies on elderly patients undergoing gastrointestinal tumor resection show that the levels of serum cortisol, norepinephrine, TNF-α, IL-6, and IL-1β in the group receiving electroacupuncture at LI4 combined with GA are lower than those in the control group. This suggests that LI4 can stabilize the internal environment under surgical trauma stress and inhibit the secretion of abnormal neurotransmitters and inflammatory factors[56]. ST36, the He-Sea point of the Foot-Yangming Stomach Meridian, is located on the lateral side of the lower leg, 3 cun below Dubi (ST35), and 1 transverse finger outside the anterior tibial crest, known as a “key health-care acupoint.” Acupuncture at ST36 exerts analgesic and anti-inflammatory effects, improves the postoperative inflammatory microenvironment, and simultaneously ameliorates gastrointestinal motility disorders to promote the recovery of postoperative gastrointestinal function. Clinical studies also demonstrate that electroacupuncture at ST36 can increase motilin/gastrin levels and reduce TNF-α/IL-6/IL-1β levels, thereby promoting the recovery of gastrointestinal function without adverse reactions[57]. PC6, the Luo-Connecting point of the Hand-Jueyin Pericardium Meridian, is located on the anterior forearm, 2 cun above the wrist crease, between the palmaris longus tendon and flexor carpi radialis tendon. In AA, PC6 is mainly used for sedation, tranquility, and regulation of overall homeostasis. Acupuncture at PC6 can alter the activity of neurochemical substances such as endorphins, serotonin, and norepinephrine in the central nervous system, activate A-β/A-δ nerve fibers, and release endorphins, thereby “desensitizing” the vomiting center and inhibiting nausea and vomiting[58]. In clinical research, LI4, ST36, and PC6 are often combined to achieve a synergistic effect of “analgesia - gastrointestinal protection - sedation and tranquility.”

Operating techniques

Filiform needle acupuncture and reinforcing-reducing manipulations are the core technical supports to ensure the effectiveness and safety of AA in surgical operations. Filiform needle acupuncture can be performed with manual manipulation alone (such as twisting, lifting, and thrusting) or connected to an electroacupuncture apparatus for quantitative stimulation. Due to the quantifiable parameters of electroacupuncture, it is widely used in clinical practice and research[59]. Disposable sterile filiform needles are preferred for filiform needle acupuncture; common specifications in research include 0.30 mm × 40 mm, 0.30 mm × 50 mm, 0.25 mm × 30 mm, etc. Before acupuncture, a comfortable position is selected according to surgical needs, such as the supine position used in studies on the recovery of postoperative intestinal function after abdominal surgery[54]. During acupuncture, a one-hand or two-hand needle insertion technique can be adopted. Straight, oblique, or transverse insertion is selected according to the anatomical location of the acupoint and the prescription requirements, and the depth is controlled to achieve Deqi (sour, numb, distended, heavy, or other needle sensations). Over-deep insertion that may injure internal organs or blood vessels should be avoided, and special caution should be exercised when inserting needles at abdominal acupoints[60]. The needle retention time in surgical operations is usually 15-30 minutes, covering the surgical incision and main operation stages. During this period, needle manipulation can be performed every 5-10 minutes to maintain the intensity of needle sensation. After treatment, the needles are removed one by one in accordance with specifications, and the needle holes are pressed to stop bleeding and observed[61]. Reinforcing-reducing manipulations are enhanced stimulation methods after Deqi is achieved in acupuncture, divided into three categories: Reinforcing manipulation, reducing manipulation, and even reinforcing-reducing manipulation, which can be realized by basic techniques such as lifting-thrusting reinforcing-reducing and twisting reinforcing-reducing[62].

Lifting-thrusting manipulation, one of the fundamental acupuncture techniques, generates reinforcing and reducing effects via vertical movement of the needle. For reinforcing manipulation, the needle is slowly inserted and rapidly withdrawn with gentle, mild stimulation; for reducing manipulation, the needle is rapidly inserted and slowly withdrawn with forceful, intense stimulation[62]. Twisting manipulation regulates stimulation intensity by rotating the needle shaft. Reinforcing twisting consists of gentle, slow rotation with mild sensation, whereas reducing twisting features heavy, rapid rotation with drastic stimulation[63].

The selection of reinforcing-reducing manipulations in AA focuses on regulating qi and blood, as well as analgesia and sedation. For deficiency-syndrome patients with deficient primordial qi or a tendency of qi consumption during surgery, AA should adopt reinforcing manipulations with gentle and small stimulation intensity to gently stimulate meridian qi, invigorate the primordial qi, and sedate. For excess-syndrome patients with excessive pathogenic factors and qi and blood stasis, reducing manipulations should be adopted with appropriately enhanced needle sensation intensity and strong stimulation intensity to dredge stagnation, unblock meridians, and relieve pain. In most clinical surgical perioperative scenarios, patients are often in a state of deficiency-excess complication and disordered qi activity. At this time, even reinforcing-reducing manipulations with medium stimulation intensity are mostly selected for AA. This not only avoids disturbing qi with strong stimulation but also effectively relieves pain and stabilizes vital signs, meeting the anesthesia auxiliary demand throughout the surgical process[64].

Electroacupuncture stimulation parameters

In the body acupoint intervention of surgical AA, the precise selection of electroacupuncture stimulation parameters is an important link, which requires individualized regulation combined with surgical type, patient constitution, and syndrome differentiation results. In terms of frequency selection, low frequency (2-10 Hz) is commonly used in situations requiring sedation, analgesia, or recovery of gastrointestinal function, which is more in line with the idea of gentle and continuous stimulation of reinforcing manipulation; high frequency (50-100 Hz) is commonly used in scenarios with strong surgical trauma stress, which is closer to the strong stimulation of reducing manipulation. The 2/100 Hz alternating wave is considered the optimal parameter combination for surgical analgesia and sedation and is often used as a common parameter for even reinforcing-reducing manipulation. This is because 2 Hz selectively activates enkephalin and 100 Hz selectively activates dynorphin, and their combined use can synergistically improve the pain threshold[8]. In terms of intensity setting, the sensory threshold (approximately 0.3-0.5 mA) is first measured, and then induced at 2 times the threshold, fluctuating up and down according to tolerance to avoid pain. It can be appropriately increased before surgery according to tolerance[65]. For example, the intensity of electroacupuncture is usually 0.5-5 mA, and the intensity of transcutaneous electrical acupoint stimulation is usually 10-20 mA, adjusted according to the patient’s sensitivity[8]. In terms of waveform selection, dense-disperse wave is widely used in AA-related research and guidelines, especially represented by 2/100 Hz alternating wave. Dense pulse and disperse pulse alternation has lower adaptability and is more beneficial to circulatory and metabolic regulation. Continuous wave can be used for specific targets (such as 2 Hz continuous wave used in insomnia and anxiety-related research), but it is less used than 2/100 Hz alternating wave in AA scenarios[8].

INDIVIDUALIZED APPLICATION OF AA IN DIFFERENT SURGICAL CATEGORIES

Standardized operating guidelines for AA

Preoperative: (1) Preoperative comprehensive assessment: Preoperative anesthesia evaluation can reduce the incidence of anesthesia and surgical complications as well as mortality. It assesses the patient’s physiological status, underlying diseases, type of surgery, etc.; and (2) Select an appropriate anesthesia method based on the evaluation and prepare a plan for perioperative complications and special situations: The main operating modes include: Traditional body acupuncture, electroacupuncture, transcutaneous electrical acupoint stimulation, auricular acupuncture, wrist-ankle acupuncture, and buccal acupuncture. Preoperatively, introduce the characteristics, methods, and procedures of acupuncture-drug combined anesthesia to the patient to alleviate preoperative anxiety and enhance patient compliance.

Intraoperative: The purpose is to reduce the dosage of anesthetics and maintain stable vital signs.

Postoperative: Provide analgesia, reduce postoperative nausea and vomiting, and prevent cognitive dysfunction, and promote the recovery of gastrointestinal function.

Individualized strategies for various types of surgery

The individualized application strategies of AA for various types of surgery are shown in Table 1.

Table 1 Individualized strategies for various types of surgery.

Surgical categories	Acupoint selection	Stimulation methods	Summary of mechanism and supporting basis	Perioperative management points	Evidence quality grading (Oxford/GRADE)	Grading rationale	Ref.
Craniocerebral surgery	Fengchi (GB20); Anmian (EX-HN22); Yuyao (EX-NH4); Cuanzhu (BL2); Shuaigu (GB8); Hanyan (GB4); Jinmen (BL63); Taichong (LR3); Shangxing (DU23); Quanliao (SI18)	For EA, sterile filiform needles are inserted obliquely or straightly into acupoints; after Deqi, an electroacupuncture instrument is connected for stimulation with 2/100Hz dense-disperse wave at a tolerable intensity, and the needles are fixed. For transcutaneous electrical acupoint stimulation, electrodes are attached to acupoints for stimulation at the same frequency with an intensity 2-3 times the sensory threshold	Acupoint stimulation activates the periaqueductal gray-RVM descending inhibitory system and promotes endogenous opioid release. Reduced nociceptive transmission from the surgical field feeds back to central pain-regulatory networks. In this way, it adjusts analgesic effects and forms a pain-control closed loop	No tracheal intubation is performed, or spontaneous breathing is maintained; postoperative nausea and vomiting is prevented (intradermal needle embedding at the Neiguan acupoint is significantly effective)	Level 2b/moderate	Included studies are single-center small-sample RCTs without double-blinding, with mild heterogeneity between studies, meeting Oxford level 2b criteria. GRADE initial high quality for RCTs, downgraded 1 level due to bias risk (no blinding) and small sample size to moderate quality	[66,67]
Cardiothoracic surgery	Yunmen (LU2); Zhongfu (LU1); Lieque (LU7); PC6; LI4		During the surgery, the dosage of anesthetics is reduced, the need for supplemental analgesics is lower, and the incidence of postoperative nausea and vomiting is also decreased, along with lower IL-6 levels and higher β-endorphin levels	It provides preoperative anxiety relief and preemptive analgesia; during surgery, it reduces anesthetic dosage, exerts anti-stress effects, stabilizes respiration and hemodynamics, and offers organ protection; postoperatively, it ensures analgesia, prevents nausea and vomiting, improves gastrointestinal function, prevents cognitive dysfunction, and enhances immunity	Level 2b/moderate	Included studies are single-center RCTs without practitioner blinding, with consistent conclusions, meeting Oxford level 2b criteria. GRADE initial high quality for RCTs, downgraded 1 level due to bias risk (no practitioner blinding) to moderate quality	[68-70]
Abdominal surgery	ST36; LI4; PC6; Sanyinjiao (SP6)		Stimulation of ST36, LI4, and PC6 activates descending pain inhibitory pathways and suppresses visceral nociceptive transmission. Altered visceral sensory input feeds back to central pain-processing regions, reinforcing analgesic regulation through a gut-brain pain-control loop	Monitor postoperative gastrointestinal function and manage dietary intake	Level 2a/Low	Meta-analysis of 17 RCTs with high heterogeneity between studies and methodological flaws in sham acupuncture controls, meeting Oxford level 2a criteria. GRADE initial high quality, downgraded 2 levels due to high heterogeneity, indirectness (flawed control scheme), and bias risk to low quality	[71]
Orthopedic surgery	Baihui (DU20); Dazhui (DU14); ST36		Acupuncture enhances endogenous opioid release and activates descending inhibitory pathways to reduce postoperative pain. Continuous feedback from peripheral inflammatory and nociceptive signals allows adaptive adjustment of central analgesic activity	Assess postoperative pain and administer additional analgesia, and guide exercise adaptation	Level 2b/moderate	Single-center RCT with inherent limitations in double-blinding implementation, meeting Oxford level 2b criteria. GRADE initial high quality for RCTs, downgraded 1 level due to bias risk (blinding limitations) to moderate quality	[26]
Thyroid surgery	Futu (LI18); LI4; PC6		Induces analgesia, regulates mean arterial pressure and heart rate, and decreases anesthetic consumption in thyroidectomy patients	Monitor hemodynamics during surgery and reduce the dosage of anesthetics	Level 2a/Low	Pooled analysis of 12 RCTs with publication bias and inconsistent EA protocols, meeting Oxford level 2a criteria. GRADE initial high quality, downgraded 2 levels due to publication bias and between-study heterogeneity to low quality	[72]

EA: Electroacupuncture; GRADE: Grading of Recommendations Assessment, Development and Evaluation; IL-6: Interleukin-6; RCT: Randomized controlled trial; RVM: Rostral ventromedial medulla.

MODERN BIOLOGICAL EXPLANATION OF ACUPOINT SPECIFICITY: A MECHANISTIC SUMMARY BASED ON AURICULAR ACUPOINTS, BODY ACUPOINTS, AND SURGICAL CATEGORIES

The modern biological interpretations of commonly used auricular and body acupoints are presented in Table 2.

Table 2 Modern biological interpretations of acupoints.

Acupoint	Category	Major mechanism	Key effect	Ref.
Hegu (LI4)	Body acupoint	Nervous system; endocrine system	Analgesia	[73]
Zusanli (ST36)	Body acupoint	Nervous system; humoral regulation; digestive system	Anti-inflammation	[74]
Neiguan (PC6)	Body acupoint	Gene expression	Anti-inflammation	[75]
Shenmen (TF4)	Auricular point	Vagus nerve	Sedation; anti-anxiety	[76,77]

LIMITATIONS OF CURRENT RESEARCH AND FUTURE DIRECTIONS

Limitations of existing studies

AA still faces several challenges in clinical application. On the safety front, the procedure itself can cause adverse events such as vascular injury and local pain[78], which partly limits its clinical acceptance. Although the available evidence has been graded as low-to-moderate in terms of quality, it should be noted that most of these studies are single-center, small-sample trials, and methodological quality varies considerably across studies. This limitation, together with the scarcity of multicenter, large-sample randomized controlled trials, has significantly impeded the global recognition and wider adoption of AA. Furthermore, the lack of standardized professional guidelines and operational protocols has led to marked variation across studies in needling techniques, point selection, and stimulation parameters, which in turn produces considerable heterogeneity in clinical outcomes[8]. A unified efficacy evaluation system is therefore urgently needed. As for mechanisms, how AA interacts with pharmacological anesthesia has yet to be clarified, and its roles in multi-organ protection, surgical stress modulation, and enhanced postoperative recovery also await deeper exploration.

In terms of study design and evidence interpretation, AA research also faces inherent methodological challenges. Patient blinding is particularly difficult, as participants often perceive needling sensations such as soreness, numbness, or distension, which may unblind them to group allocation, while practitioner blinding is virtually impossible. Although sham acupuncture using non-penetrating needles or superficial needling at non-acupoints has been widely adopted as a placebo control, such approaches may still produce physiological effects via cutaneous afferent activation and are not entirely inert, potentially leading to an underestimation of the true treatment effect. These methodological issues collectively introduce risks of performance and detection bias. Moreover, publication bias should not be overlooked, as studies with positive results are more likely to be published, which may overestimate the evidence base for AA. Therefore, findings from current AA trials should be interpreted with caution.

Key directions for future research

To address the above challenges, future research should focus on several key directions. First, large-scale, multicenter, and rigorously designed randomized controlled trials are needed, with integration of real-time neuroimaging techniques to dynamically elucidate the central regulatory mechanisms of AA across different surgical settings. These studies should simultaneously develop a core outcome set for AA to unify efficacy metrics and enhance comparability across trials. Second, industry-wide standards and operational protocols covering acupoint selection, stimulation parameters, and procedural steps should be established, and machine learning approaches can be applied to construct intelligent models for acupoint selection to improve precision and personalization. Third, the role of AA within enhanced recovery after surgery protocols should be clearly defined, and optimal integration models with existing perioperative management strategies should be explored. Finally, standardized training and certification programs should be implemented to ensure procedural consistency, and systematic cost-effectiveness analyses should be conducted to assess the clinical value of AA and provide a solid rationale for its broader adoption.

CONCLUSION

This review provides a systematic synthesis of the operational standards, technical details, and biological mechanisms underlying AA application in surgical procedures. Clinical trial findings show that the combined use of auricular and body acupoints produces analgesic, sedative, anesthetic-sparing, complication-reducing, and recovery-accelerating effects across diverse surgical procedures. Technically, the main auricular strategy involves stimulating Shenmen and the corresponding surgical-site reflex zones via auricular acupressure or needling. Body acupoints are selected based on local, distal and empirical principles, and combined with optimized electroacupuncture parameters, to produce personalized strategies for different surgical categories. Mechanistically, AA acts through a synergized effect of neural, endocrine and immune pathways, in which acupuncture stimulates peripheral afferent fibers, resulting in the central release of endogenous opioid peptides to modulate analgesia, and vagal reflexes control visceral functions. At the endocrine level, AA dampens surgical stress by suppressing the HPA axis and activating the sympatho-adrenomedullary system. Immunologically, acupuncture initiates signaling by activating local mast cells; via neural reflex pathways, this signaling exerts anti-inflammatory effects and contributes to multi-organ protection.

Current limitations of research are as follows: Lack of high-quality evidence, lack of standardized protocols, and fragmented understanding of mechanisms. Future research should focus on multicenter randomized controlled trials, application of multi-omics technology, and optimization of individualized precision strategies. Collectively, these will lead to integration of AA into the modern surgical anesthesia system and provide a Chinese perspective to optimize perioperative management.