Buccal Acupuncture Reduces the Dose of Sufentanil Needed in Laparoscopic Gynecological Surgery

Introduction

Buccal acupuncture is an emerging pain-free therapy that stimulates specific acupoints on the cheek to treat systemic diseases, especially pain [1], and may be related to the upregulation of β-endorphin (β-EP) and cholecystokinin 8 (CCK-8) levels. Buccal acupuncture has an immediate and definite effect, and its main features include the rapid relief of pain, numbness, and discomfort. Its applications and promotion have broad prospects. However, there are few studies on the efficacy of buccal acupuncture therapy in relieving pain during surgical anesthesia, and determining whether the dosage of analgesic drugs can be reduced requires many clinical studies conducted in different diseases and populations, laying the foundation for their clinical promotion. Clinical studies on different diseases and populations are required to lay the foundation for clinical promotion. This study aimed to evaluate the effects of buccal acupuncture on various intraoperative and postoperative parameters in patients undergoing laparoscopic gynecological surgery. Specifically, we examined hemodynamic changes, anesthetic and analgesic dosages, serum inflammatory markers, and the incidence of adverse effects such as postoperative nausea and vomiting. The sedation and pain scores were recorded to assess patient comfort during the procedure. By analyzing these factors, this study sought to provide valuable insights into the potential benefits of buccal acupuncture as a complementary therapy for perioperative pain management. The ultimate goal was to contribute to the growing body of evidence supporting the use of buccal acupuncture as an adjunct to conventional analgesia, with the hope of improving patient outcomes and reducing reliance on opioids.

Material and Methods

STUDY SUBJECTS:

This study was registered in the China Clinical Trial Registry after approval by the hospital ethics committee, and informed consent was obtained from all the patients. Eighty patients who underwent laparoscopic gynecological surgery in our hospital between April 2023 and June 2024 were selected as the study subjects. The inclusion criteria were: 1) American Society of Anesthesiologists (ASA) grade II to III; 2) Body mass index (BMI) ≤30 kg/m²; 3) Patients signed informed voluntary participation form. Exclusion criteria were: 1) Combined with severe liver, kidney, and heart dysfunction; 2) Combined with a family history of mental illness; 3) Cognitive dysfunction or contraindications to laparoscopic surgery; 4) Coagulation function and immune dysfunction; 5) Long-term use of sedatives and sleeping pills. Laparoscopic hysterectomy combined with salpingectomy was performed in 51 cases, myomectomy combined with salpingectomy in 7 cases, oophorectomy in 15 cases, and myomectomy in 7 cases. The laparoscopic gynecological surgery site was in the pelvic cavity; therefore, the same acupoints were selected to reduce study bias.

SAMPLE SIZE ESTIMATION:

As this study was a randomized controlled trial, the following formula for sample size calculation was used [2]:

The significance level (α) was set at 0.05 for a two-sided test, resulting in Z_1–α/2=1.96. The test efficacy (β) was set as 0.9, yielding Z_1–β=1.28. k denotes the number of groups, with k set to 2. σ denotes the standard deviation of each indicator at various time points (μ_max and μ_min), and was used to estimate the effect size of each indicator across the 2 groups. μ_max and μ_min values were obtained from a previous pilot study. For indicators that did not conform to a normal distribution, we applied transformations to ensure that they adhered to normality prior to the analysis, which represented the difference between the maximum and minimum cluster means. The required sample size was calculated as n=40.

GROUPING AND TREATMENT:

The patients were randomly divided into 2 groups using a random table: control and buccal acupuncture groups, with 40 patients in each group (Figure 1). The buccal acupuncture group underwent buccal acupuncture intervention after anesthesia induction by the same physician. The acupuncture points were selected according to the “Cheeks Acupuncture Therapy” [3], including the back point of the cheek on both sides (below the temporomandibular joint at the lower edge of the zygomatic arch root), the waist point (the midpoint of the line connecting the back point and the sacral point), the sacral point (16 mm above the mandibular angle) and the pelvic point (the midpoint of the line connecting the front edge of the inner angle of the mandible and the waist point), with a total of 8 points and 8 needles (Figure 2A, 2B). The face was routinely disinfected, and a 0.16×15 mm cannula acupuncture needle was quickly inserted vertically at a depth of 10–15 mm. The needle was retained until the end of surgery, after which it was removed. The control group underwent anesthesia induction and maintenance without buccal acupuncture.

ANESTHESIA MANAGEMENT:

After entering the operating room, patients were managed by peripheral intravenous placement and monitoring of the electrocardiogram (ECG), heart rate (HR), blood pressure (BP), blood oxygen saturation (SpO2), and bispectral index (BIS). We performed noninvasive cuff blood pressure monitoring of systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), and inhalation of pure oxygen (flow rate, 3 L/min) for 10 min through a mask. Anesthesia induction used etomidate 0.4 mg/kg, sufentanil 0.4μg/kg, and cisatracurium 0.2 mg/kg. After rapid induction, endotracheal intubation was performed and the anesthesia machine was connected to volume-controlled mechanical ventilation. Anesthesia maintenance used propofol 4–6 mg/kg/h, remifentanil 0.2 ug/kg/min, cisatracurium 0.2 ug/kg/min intravenous injection to maintain muscle relaxation and maintain BIS value at 40–60. If there was inadequate pain relief, we added sufentanil 0.1–0.2 ug/kg if the BIS value was greater than 60 or systolic blood pressure increased by more than 20% of the baseline value. Lactated Ringer’s solution was administered intravenously at 400–600 ml/h during the surgery. If the SBP dropped by more than 20% of the baseline value, phenylephrine 50–100 μg was injected intravenously. If the systolic blood pressure increased by more than 20% of the baseline value and the effect of additional sufentanil was insufficient, urapidil 5–10 mg was injected intravenously. If bradycardia occurred (HR ≤60 beats/min), atropine 0.3–0.5 mg was administered intravenously. If tachycardia occurred (HR ≥100 beats/min), metoprolol 1–3 mg was injected intravenously. These vasoactive drugs can be repeatedly used. The injection of cisatracurium was stopped half an hour before the end of the operation, and sufentanil 0.1–0.2 ug/kg was added simultaneously. All anesthetic drugs were discontinued at the end of the surgery when the incision was sutured. After the operation, the patient was transferred to the post-anesthesia care unit. When the patient regained consciousness and was breathing spontaneously, the tidal volume (VT) was ≥5 ml/kg, respiratory rate (RR) was ≥12 times/min, and the swallowing reflex was active, the endotracheal tube was removed. When the patient’s postoperative visual analog scale (VAS) pain score was ≥3, intravenous nonsteroidal drugs were injected for rescue analgesia, and the injection was repeated if necessary.

OUTCOME MEASURES:

SBP, DBP, MAP, and HR were recorded at the time of entering the operating room (T0), 5 min after anesthesia (T1), during surgical skin incision (T2), 5 min after removal of the airway tube (T3), 6 h after surgery (T4), and 24 h after surgery (T5). The intraoperative dosages of propofol and remifentanil and the use of vasoactive drugs were recorded. Venous blood samples were collected at T0, T3, and T5, and the concentrations of plasma interleukin-6 (IL-6), serum amyloid protein (SAA), C-reactive protein (CRP), and procalcitonin (PCT) were measured using magnetically sensitive immunoassay kits for inflammatory response indicators. We added 50 μl of venous blood to 50 μl of the buffer solution and mixed it thoroughly. Then, 50 μl of the mixed solution was dropped onto the magnetically sensitive reagent card, and the card was inserted into the magnetically sensitive detector. The relevant procedures were performed according to the manufacturer’s instructions. The Ramsay Sedation Scale (RSS) is a subjective sedation scoring system, and the visual analog scale (VAS) is a commonly used pain assessment tool that is widely used in various clinical scenarios where sedatives or anesthetics are used. Appropriate sedation and analgesia are crucial for patient recovery, and the patients’ RSS and VAS scores at T4 were recorded by an anesthesia nurse who was unaware of the study groups. The patients underwent pain scoring 24 h after surgery. The RSS score has a total score of 6 points: 1 point indicated restless, irritable; 2 points indicates calm; 3 points indicates cooperative with treatment; 4 points indicates sleepy, able to cope with strong stimulation; 5 points indicates sleepy, unable to cope with stimulation; and 6 points indicates deep sleep, no response. The VAS score evaluates the degree of pain, with a total score of 10 points: 0 points for no pain; 1–3 points for mild pain; 4–6 points for moderate pain; and 7–10 points for severe pain. The higher the score, the more severe the pain is. Bleeding and infection during acupuncture in the cheek needle group were recorded, as were the number of remedial analgesia cases within 24 h after surgery, chills, nausea, and vomiting, and postoperative shoulder discomfort in both groups.

STATISTICAL ANALYSIS:

Data analysis was performed using SPSS 21.0. Qualitative data were described by composition ratio or frequency, and intergroup comparisons were performed using the χ² test or Fisher’s exact probability test. Continuous variables were tested for normality, and those meeting the normal distribution criteria were presented as mean±standard deviation (SD). Two-sided independent-sample t-tests were used to compare the 2 groups. Quantitative data with skewed distributions were described using M (P25, P75), and intergroup comparisons were performed using the Mann-Whitney U test. Differences were considered statistically significant at P<0.05.

Results

GENERAL INFORMATION ABOUT PARTICIPANTS:

The baseline characteristics of the 2 groups, including age, BMI, ASA grade, anesthesia time, and operation time (all P>0.05), were not significantly different, and they were comparable (Table 1).

INTRAOPERATIVE UTILIZATION OF ANESTHETIC DRUGS:

The average dosage of sufentanil in the control group was significantly higher than that in the buccal acupuncture group (all P<0.05). There were no statistically significant differences in the dosages of remifentanil and propofol or the usage rates of urapidil, phenylephrine, atropine, and metoprolol between the 2 groups (all P>0.05) (Table 2).

COMPARISON OF HEMODYNAMIC INDICES BETWEEN THE 2 GROUPS OF PATIENTS AT T0–T4:

There were no statistically significant differences in SBP, DBP, HR, or MAP between the 2 groups at T0–T5 (all P>0.05) (Table 3).

COMPARISON OF INFLAMMATORY INDICATORS BETWEEN THE 2 GROUPS OF PATIENTS:

There were no statistically significant differences in IL-6, SAA, CRP, or PCT levels between the 2 groups at T0, T3, or T5 (all P>0.05) (Table 4).

COMPARISON OF RSS SEDATION SCORES AND VAS PAIN SCORES BETWEEN THE 2 GROUPS OF PATIENTS AT T4:

There were no statistically significant differences in the RSS and VAS pain scores between the 2 groups at T4 (all P>0.05) (Table 5).

COMPARISON OF REMEDIAL ANALGESIA, CHILLS, NAUSEA, VOMITING, AND SHOULDER DISCOMFORT WITHIN 24 HOURS AFTER SURGERY BETWEEN THE 2 GROUPS:

Within 24 h after surgery, there were no statistically significant differences in remedial analgesia, chills, nausea, vomiting, or shoulder discomfort between the 2 groups (all P>0.05) (Table 6).

Discussion

Minimally invasive laparoscopic surgery is a commonly used surgical method for treating gynecological diseases [4]. However, pain caused by surgical injury is a critical factor that affects patient recovery [5]. Analgesics and sedatives are often used during anesthesia to reduce pain, with opioid analgesics being the primary treatment option [6]. However, opioids frequently cause adverse effects [7]. Therefore, some researchers have proposed reducing or eliminating the use of opioids through the combined use of multiple drugs or techniques [8,9]. However, there are few clinical studies on the use of buccal acupuncture therapy for analgesia during anesthesia. This situation warrants further investigation.

Buccal acupuncture therapy is based on biological holography theory. It projects the human body onto the cheek (Figure 2C). It is an emerging microneedle technology that treats systemic diseases using acupuncture at specific points on the cheek. It has a definite therapeutic effect on pain-related diseases [11]. Acute pain treatment is quick and involves a short treatment cycle, whereas the treatment cycle for chronic pain is longer.

Recent studies have shown that cheek acupuncture has significant therapeutic effects in treatment of pain. In a rabbit model of rheumatic pain, buccal acupuncture upregulated the levels of β-endorphin (β-EP) and cholecystokinin-8(CCK-8) in the cerebrospinal fluid, and its analgesic effect was superior to that of other acupuncture methods [12]. Neuropathic pain is very severe, and buccal acupuncture can relieve it while avoiding adverse effects [13]. Thus, this alternative treatment strategy is promising. Buccal acupuncture can also achieve good therapeutic effects on soft-tissue pain, which is relatively common in clinical practice [14]. Blocking the transmission of pain signals to the central nervous system and alleviating the release of inflammatory cytokines may be mechanisms of analgesia [15,16]. IL-6 is an important regulatory factor in the inflammatory response; CRP is not only an inflammatory marker but also participates in the inflammatory response. PCT reflects the activity level of the systemic inflammatory response, and SAA is an acute inflammatory substance that can rapidly and significantly increase after being stimulated by inflammation; acupuncture and moxibustion analgesia is a complex process that involves neural regulation, changes in humoral factors, and other aspects. It is related to the activation of the A δ and C nerve fibers in local tissues, regulation of neurotransmitters, endogenous analgesic substances, and inflammatory reactions. Acupuncture and moxibustion analgesia are complex processes, involving neural regulation, changes in humoral factors, and other aspects. It is related to activation of A δ and C nerve fibers in local tissues, regulation of neurotransmitters, endogenous analgesic substances, and inflammatory reactions.

These studies confirmed the efficacy of buccal acupuncture and demonstrated its immediate analgesic effects. Therefore, we were interested in the efficacy of buccal acupuncture for anesthesia and analgesia during surgery. After reviewing the literature, we found that the use of buccal acupuncture for intraoperative analgesia is still in its infancy. Our study included patients who underwent laparoscopic gynecological surgery as research participants. The control group received conventional anesthesia, whereas the buccal acupuncture group received conventional anesthesia in conjunction with the buccal acupuncture treatment. Laparoscopic surgery interferes with the chest, abdomen, and pelvic cavity; therefore, we selected back, waist, sacral, and pelvic acupoints. These acupoints have analgesic effects on the chest, abdomen, and pelvic cavity. Only 1 article has reported the application of buccal acupuncture therapy for intraoperative anesthesia and analgesia [9]. Research has shown that buccal acupuncture can reduce the dosage of sufentanil and reduce inflammatory response indicators, which is beneficial for patient recovery. In our study, the intraoperative sufentanil dosage of patients in the buccal acupuncture group was significantly lower than that of the control group, which is consistent with their research results. However, there were no statistically significant differences in the dosage or usage rates of other anesthetic drugs, intraoperative hemodynamic indices, inflammatory response indicators, postoperative sedation and analgesia scores, incidence of postoperative rescue analgesia (VAS pain score ≥3, intravenous nonsteroidal drugs injected), chills, nausea, vomiting, or shoulder discomfort (soreness and shoulder pain). Two patients in the buccal acupuncture group experienced slight bleeding after acupuncture; however, no infections occurred, which differs from their research results. This may be related to the differences in the research subjects, anesthesia schemes, and acupoint selections used in the 2 studies. These results, without significant differences, also indicate that the use of buccal acupuncture therapy for intraoperative anesthesia and analgesia does not aggravate fluctuations in the patients’ hemodynamic indices and inflammatory responses, as well as the incidence of adverse reactions, reflecting the safety of this therapy. Buccal acupuncture may have replaced some of the analgesic, anti-inflammatory, and hemodynamic effects of sufentanil.

Sufentanil is a potent opioid analgesic with strong analgesic effects, wide safety range, and few adverse reactions [17,18]. However, some patients experience poor analgesic effects owing to individual differences, genetic polymorphisms [19], and drug interactions [20,21]. Thus, low-dose sufentanil may exacerbate hemodynamic fluctuations and inflammatory reactions. Adequate analgesia can maintain good hemodynamics [22] and reduce inflammatory responses [23]. Our study showed that buccal acupuncture can reduce the dose of sufentanil used. Choosing and applying reasonable analgesic techniques can reduce the use of opioids while providing good analgesia [24]. Our results showed that intraoperative anesthesia combined with buccal acupuncture analgesia could achieve the same analgesic, sedative, stable hemodynamic, and reduced inflammatory effects as a smaller dose of sufentanil, without increasing the incidence of adverse events. This is beneficial in accelerating patient recovery. Differences in inflammatory responses may be discovered in future multicenter studies, which may make buccal acupuncture combined with conventional anesthesia more effective in treating such patients. Cancer pain [25], postoperative pain [26], acute pain [27], chronic pain, and other types of pain [28] may be treated with buccal acupuncture, which is associated with neurochemical or neurophysiological mechanisms [29,30,31] and warrants further exploration.

Conclusions

In summary, our study confirmed the use of buccal acupuncture in patients undergoing laparoscopic gynecological surgery. Administering acupuncture to the back, waist, sacral, and pelvic points on both sides of the cheek can reduce the dosage of sufentanil (Table 2) without aggravating fluctuations in hemodynamics, inflammatory response, and the incidence of adverse reactions. It is safe, painless, easy to use, and highly accepted by patients, with a low incidence of adverse events. However, further research is required to confirm the underlying scientific mechanisms and clinical efficacy.