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Anesthesia & Analgesia:
doi: 10.1213/ane.0b013e318195b78f
Analgesia: Pain Medicine: Research Reports

Capsicum Plaster at the Hegu Point Reduces Postoperative Analgesic Requirement After Orthognathic Surgery

Kim, Kyo S. MD, PhD*; Kim, Kyu N. MD*; Hwang, Kyung G. DMD, PhD†; Park, Chang J. DMD, PhD†

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From the Departments of *Anesthesiology, and †Dental Surgery, Hanyang University Hospital, Seoul, Korea.

Accepted for publication September 9, 2008.

Address correspondence and reprint requests to Kyo Sang Kim, MD, PhD, Department of Anesthesiology, Hanyang University Hospital, #17 Haengdang dong, Sungdong gu, Seoul 133-792, Korea. Address e-mail to kimks@hanyang.ac.kr.

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BACKGROUND: Capsicum plaster at classical Chinese acupoints is an alternative to acupuncture, which has been used as an effective method for preventing postoperative nausea and vomiting, sore throat, and pain. In this study, we investigated the postoperative analgesic efficacy of capsicum plaster at Hegu (LI 4) acupoints in patients after bilateral sagittal split ramus osteotomy.

METHODS: A double-blind, sham-controlled study was conducted with 84 patients undergoing orthognathic surgery, and who were randomly assigned to three treatment regimens (n = 28 each): Hegu group = capsicum plaster at Hegu acupoints and placebo tape on the shoulders as a nonacupoint; sham group = capsicum plaster on the shoulders and placebo tape at Hegu acupoints; and control group = placebo tape at Hegu acupoints and on the shoulders. The capsicum plaster was applied before induction of anesthesia and maintained for 8 h per day for 3 postoperative days.

RESULTS: The total amount of patient-controlled analgesia, containing 6.5 μg/mL fentanyl and 1.2 mg/mL ketorolac, administered in the first 24 h after the operation was decreased in the Hegu group (26.8 ± 3.4 mL) compared with the control (44.2 ± 7.3 mL) and sham (42.1 ± 6.9 mL) groups (P < 0.01). The incidence of postoperative nausea and vomiting and the need for rescue medication were reduced, and the overall satisfaction score was greater in the Hegu group compared with other groups (P < 0.01).

CONCLUSION: The capsicum plaster at the Hegu acupoints decreased the postoperative opioid requirements and opioid-related side effects in patients after orthognathic surgery.

Acupuncture has been reported to be an effective and important adjuvant for pain control during the postoperative period after dental surgery.1–3 The Hegu (LI 4) acupuncture point has been widely used to control dental pain.1–3 However, most studies are either limited to tooth extraction or to the duration of acupuncture, lack sufficient sample size, fail to provide adequate postoperative treatment, fail to evaluate the placebo effect or lack an adequate control group. The orthognathic surgical procedure that comprises bilateral sagittal split ramus osteotomy (BSSRO) is the most painful intervention among the oral and maxillofacial procedures.4 Patient-controlled analgesia (PCA) with opioid analgesics has been reported to be an effective and important postoperative pain management after orthognathic surgery.5,6

Capsicum plaster (PAS®, Sinsin Pharm, Korea), which contains 345.80 mg powdered capsicum and 34.58 mg capsicum tincture on a sheet (12.2 × 16.4 cm2), is an alternative to acupuncture, first developed and described by the Korean Buddhist priest Namsan.7 Capsicum plaster applied to the acupuncture points has been reported to be an effective method for preventing postoperative nausea and vomiting (PONV),8,9 postoperative sore throat,10 and postoperative pain.11,12 Although acupuncture and related techniques may not provide sufficient pain relief as the sole modality for the treatment of postoperative pain, they could prove valuable as an adjuvant to the PCA method in the management of acute postoperative pain.12,13

The present, prospective, randomized, double-blind, and sham-controlled study was designed to test the hypothesis that application of capsicum plaster to Hegu acupoints reduces the analgesic requirement, side effects and recovery profile in the early postoperative period after orthognathic surgery.

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The protocol of this study was approved by the Hospital Ethics Committee, and all patients read, understood and signed an informed consent form. In this double-blind, placebo- and sham-controlled study based on a preliminary study, 84 patients (ASA I-II), aged 17 to 53 yr, were eligible for orthognathic surgery that comprised elective BSSRO. Exclusion criteria included allergy to opioids, addiction to any drugs or alcohol or the use of such substances preoperatively, any major psychiatric, neurologic, or cardiopulmonary disorder, previous acupuncture treatment and pregnancy or nursing mothers. One surgeon blinded to treatment assignment performed the dental procedures. All patients were placed in maxillomandibular fixation after surgery.

The patients were randomly assigned to the Hegu group (n = 28), sham group (n = 28), and control group (n = 28). Randomization was based on computer-generated codes that were placed in sealed, opaque envelopes containing random allocation information for each identification number. In the Hegu group, capsicum plaster (5 × 5 mm2) was taped at bilateral Hegu points (LI 4), located on the dorsum of the hand, between the first and second metacarpal bones, at the mid-point of the second metacarpal bone and close to its radial border,2 and an inactive tape (5 × 5 mm2) was taped at the deltoid region of both shoulders as a nonacupoint.13 Hegu acupoint was chosen because this point is traditionally considered to possess the most therapeutic effect on dental pain.1–3 In the sham group, capsicum plaster (5 × 5 mm2) was taped at both deltoid regions, and an inactive tape (5 × 5 mm2) was taped at both Hegu points. In the control group, an inactive tape (5 × 5 mm2) was taped at both Hegu points and at both deltoid regions. After the capsicum plaster was taped to the above sites, a plastic adhesive covered the entire region. The capsicum and placebo treatment were both performed for a period of 30 min before induction of anesthesia in the first operation, and was maintained for 8 h per day for 3 postoperative days. Capsicum plaster was taped by an acupuncturist, who was not involved with subsequent patient management or assessment. The patients, as well as the anesthesiologist and the nursing staff, were unaware of the patient grouping. The present study was designed as a double-blind study; although the acupuncturist was not blinded, the patients and the evaluator remained blinded.

No premedication was given and anesthesia was induced by IV administration of 5 mg/kg thiopental and 0.6 mg/kg rocuronium. After nasotracheal intubation, anesthesia was maintained with 2%–3% sevoflurane and nitrous oxide in 50% oxygen. Muscle relaxation was maintained with rocuronium, which was titrated to provide one or two twitches in response to supramaximal electrical stimulation of the ulnar nerve at the wrist. The standard monitors were used intraoperatively and no additional opioid analgesic medications were administered during the intraoperative period. At the end of anesthesia, the residual neuromuscular blockade was reversed with an IV combination of 0.05–0.075 mg/kg neostigmine and 0.005–0.01 mg/kg glycopyrrolate. Active surface warming was used to keep the core temperature normothermic (>36°C). After completion of the surgical procedure, the anesthesiologist providing postoperative care determined the extubation timing, and the patients were tracheally extubated when the extubation criteria were fulfilled.14

Patients were sent to the recovery room postoperatively, where they immediately received a bolus of IV 50 μg fentanyl and 30 mg ketorolac for pain control. The operational aspects of the PCA device (WalkMed PCA, Mckinley Medical, Wheat Ridge) were explained to each patient at the time of the initial preoperative visit and were again reviewed with each patient before initiating PCA therapy in the recovery room. The PCA device was programmed to allow a 1 mL/h as a basal infusion, with a minimal lockout interval of 15 min and a maximal hourly dose of 2 mL, which contained 6.5 μg/mL fentanyl and 1.2 mg/mL ketorolac with normal saline, for a total of 100 mL. Supplemental bolus doses of 30 mg ketorolac were administered IM if the patient was unable to achieve adequate pain relief from the PCA device. At 48 h, the PCA therapy was discontinued in all patients, and the single effect of the capsicum plaster was evaluated during the 48–72 h period. The analgesia was comprised of supplemental doses of ketorolac, if required.

Vomiting, including retching, and other adverse side effects were assessed by an independent observer who was unaware of the patient randomization and the capsicum plaster treatment. A 4 mg ondansetron IV was administered promptly as a rescue antiemetic when requested. PONV was assessed on a 3-point scale: 0 = no symptoms, 1 = only nausea, 2 = vomiting. The highest score reported during the study determined the category to which a patient was allocated. Thus, the patients who experienced both nausea and vomiting were included in the vomiting category. An anesthesiologist blinded to group allocation evaluated the patients when they were sufficiently awake and alert postsurgery and recorded the data. The pain scores at rest were assessed with a standard 100-mm visual analog scale (VAS, 0 = no pain to 100 = worst pain imaginable). The postoperative analgesic requirement, the number of PCA demands, doses of rescue analgesic, opioid-related side effects (yes or no), PONV and the need for rescue antiemetic drugs were recorded at 1, 6, 24, 30, 48, 54, and 72-h intervals during the postoperative period. At 72 h, patients evaluated the overall quality of their postoperative analgesia in the recovery process using a 4-point rating scale (1 = very satisfied, 2 = satisfied, 3 = unsatisfied, 4 = very unsatisfied).

Statistical analyses were performed using SPSS 12.0 for Windows (SPSS, Chicago, IL). The initial sample size estimation showed that 27 subjects should be included in each group to ensure a power of 0.80 for sufficiently detecting a 10% difference in VAS pain scores during the first 24 h after bimaxillary osteotomy.6 The α error was assumed to be 0.05, and the mean ± sd (42.1 ± 9.2) was estimated from initial pilot observations. Parametric data were analyzed using two-way repeat analysis of variance in combination with the Tukey test. Nonparametric data were evaluated using the Kruskal Wallis one-way analysis of variance with Mann-Whitney rank sum test as the post hoc test. Comparison of the side effects, the number of patients who vomited or were nauseous, the number of patients requesting the rescue antiemetic and patient satisfaction were analyzed using the Fisher’s exact tests. Data are presented as mean and standard deviation, median and ranges, percentages and number of patients. A value of P < 0.05 was considered statistically significant for all results.

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There were no significant intergroup differences in the patients’ age, gender, weight, height, ASA physical status, duration of anesthesia and postoperative time to tracheal extubation (Table 1). The total PCA volume and the number of PCA demands during the 48 h, and the number of supplemental analgesic requests during the 72 h postoperatively, were significantly decreased in the Hegu group compared with control and sham groups (P < 0.01) (Table 2). As a result, the total amount of PCA administered in the first 24 h after the operation was significantly decreased in the Hegu group (26.8 ± 3.4 mL; 174.2 ± 22.1 μg fentanyl and 32.2 ± 4.1 mg ketorolac) compared with the control (44.2 ± 7.3 mL; 287.3 ± 47.5 μg fentanyl and 53.0 ± 8.8 mg ketorolac) and sham (42.1 ± 6.9 mL; 273.7 ± 44.9 μg fentanyl and 50.5 ± 8.3 mg ketorolac) groups (P < 0.01) (Table 2). Pain intensity in the Hegu group patients was significantly lower than in other groups (P < 0.001) (Fig. 1). The incidences of nausea, vomiting, rescue antiemetics, and pruritus during the 72 h after surgery were significantly reduced in the Hegu group compared with other groups (P < 0.01) (Table 3). On the postoperative interview at 72 h, 82%–96% of the patients reported their postoperative pain was adequately treated, and the overall satisfaction score was significantly greater in the Hegu group compared to other groups (P < 0.01) (Table 4). The only side effect noted in this study was a mild burning sensation with erythema in two patients in the Hegu group and one patient in the sham group, which resolved spontaneously within 24 h after removing the capsicum adhesive tape.

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The results of this study indicate that capsicum plaster at Hegu acupoints contributes to a postoperative analgesic effect. In addition, the incidence of PONV and the number of patients who required rescue antiemetic within the first three postoperative days were significantly lower after orthognathic surgery.

Contemporary orthognathic surgery has allowed the possibility to reposition either one or both jaws in one piece or as segmental osteotomies. This has provided the patient, who has a severe dentofacial problem, with the option of having all components of their malocclusion and facial esthetic concerns addressed.15 There is a close relation between the length of the surgical procedure and postoperative pain. The results of this study show that 82% of the control and sham groups had VAS values over 60 mm at 1 h postoperatively (Fig. 1), similar to results from previous studies.6 These data show that orthognathic surgical procedures require strict postoperative pain management.

The mechanism by which capsicum plaster at Hegu acupoints achieves its analgesic and antiemetic effect is not yet fully understood. Topically applied capsaicin blocks the transport and synthesis of substance P from sensory C-fibers.16 As a result, repeated applications of capsaicin are suitable for the treatment of neuropathic pain or musculoskeletal disorders, with or without inflammatory components.17 The capsicum plaster has an effect similar to acupressure or acupuncture, and the sites of stimulation are the same.7 Acupuncture at Hegu acupoints evoked specific deactivation at the primary somatosensory cortex contralateral to the hand stimulated and bilateral secondary somatosensory cortex, areas known to be related to pain.18,19 In particular, Yang et al.20 demonstrated that the excitation of the Hegu acupoints inhibited the actions of the jaw and face projection area in a brain magnetic fields study, offering a possible explanation of why performance of acupuncture at Hegu acupoints effectively inhibits dental pain. The authors of this study hypothesize the main analgesic effects may be induced by nonspecific physical stimulation of the capsaicin receptor rather than topical pharmacologic actions.

The preoperative acupuncture stimulation at Hegu acupoints has an opioid-sparing effect of 65% at high transcutaneous acupoint electrical stimulation and 34% at low stimulation, during the early postoperative period after lower abdominal procedures while also reducing opioid-related side effects.21 The current study also demonstrates that the capsicum plaster at the Hegu acupoints significantly decreased the requirement (39%) of opioid analgesics and the incidence of PONV (35%) in the postoperative period, compared with the sham and control groups. The reduction in the side effects may have been the result of decreased opioid requirements and improved postoperative pain relief, resulting in increased overall patient satisfaction. Because many factors can influence the effect of this nonpharmacologic therapy on postoperative pain, this study was designed to examine the effect of the specific site of stimulation (i.e., acupoint versus nonacupoint) on the opioid analgesic requirement and the incidence of opioid-related side effects.10–13

De-Qi is a typical sensation that is associated with proper acupuncture needle position. Many practitioners consider this sensation to be crucial in achieving the effect of acupuncture.22 De-Qi is usually not elicited when the capsicum plaster is applied to the acupoint. In this study, an experienced acupuncturist confirmed the correct placement of the capsicum plaster in the Hegu point and the placement site in the shoulder.

After the orthognathic surgery, the recommended postoperative intubation time was 8 h in order to avoid respiratory complications.23 In this study, tracheal extubation was also performed approximately 8 h after the end of the surgery (Table 1). A limitation of the present study is that VAS pain scores recorded at 1 and 6 h were not truly reflective of the pain from surgical sites due to the influence of intubation.

In conclusion, application of capsicum plaster to Hegu acupoints decreased the postoperative opioid requirements and opioid-related side effects in patients after BSSRO surgery.

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