The incidence of postoperative nausea and vomiting (PONV) for patients undergoing total abdominal hysterectomy is as much as 90%, and one of the causative factors is the use of opioid analgesia (1,2). Pharmacologic approaches have been investigated to reduce PONV (3–6). Nonpharmacologic techniques, such as acupuncture (7), electroacupuncture (8), transcutaneous electrical nerve stimulation (9), acupoint stimulation (10), and acupressure (11,12) of the Chinese acupuncture point Pericardium 6 (P6) have been examined as alternatives to antiemetics. Schlager et al. (13) reported that Korean hand acupressure (K-K9) also reduced postoperative vomiting in children after strabismus surgery.
In contrast to acupressure or acupuncture, capsicum plaster (PAS; Sinsin Pharm., Korea), which contains powdered capsicum 345.80 mg and capsicum tincture 34.58 mg on a sheet (12.2 × 16.4 cm2), at the Korean hand acupuncture point (KHAP) is a new method first developed and described by the Korean Buddhist priest Namsan (14). Although this method is widely used in Korea, Western medicine has taken hardly any notice of it, and little research is being performed in this field. PAS is inexpensive (1$ per five sheets) and is used effectively in the treatment of motion sickness.
K-D2, the KHAP in Koryo Hand Therapy (KHT), which was described by the Korean physician Yoo (15), is not identical to the Chinese acupuncture point P6, whose antiemetic effect has been ascertained in numerous studies (7–12). Therefore, we designed a randomized, double-blinded, placebo-controlled study to test the hypothesis that less PONV would be experienced by patients undergoing abdominal hysterectomy who were given PAS at K-D2 compared with those given either PAS at P6 or placebo tape at K-D2.
The protocol of this study was approved by the hospital ethics committee, and informed consent was obtained from all patients. In this double-blinded, placebo-controlled study based on a preliminary study, 160 patients (ASA status I–II) scheduled for abdominal hysterectomy were assigned randomly to a control group (n = 60), the K-D2 group (n = 50), or the P6 group (n = 50). Randomization was based on computer-generated codes that were maintained in sequentially numbered opaque envelopes. Patients receiving antiemetic medications, a histamine H2-receptor antagonist, or tranquilizers within 72 h before surgery and those with hypertension were excluded to prevent interference secondary to drug interactions.
In the K-D2 group, PAS (5 × 5 mm2) was applied at the K-D2 point, located on the lateral distal phalanx of the index finger of both hands (Fig. 1). In the P6 group, PAS (5 × 5 mm2) was applied at the P6 point of both forearms. The P6 (Neiguan) point (on the Pericardium Channel of Hand-Jueyin) is located 3 cm proximal to the distal wrist crease and lies between the tendons of the palmaris longus and flexor carpi radialis (11). In the control group, an inactive tape (5 × 5 mm2) with no PAS was fixed at the K-D2 point of both hands. The investigator who set up the PAS method 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. Both PAS and placebo treatment were performed for a period of 30 min before the induction of anesthesia and were maintained for 8 h.
No premedication was given, and anesthesia was induced by IV administration of thiopental 5 mg/kg and vecuronium 0.1 mg/kg. After tracheal intubation, anesthesia was maintained with 2%–3% enflurane and nitrous oxide in 33% oxygen, and vecuronium was given during surgery as required. The usual monitors were used during surgery. A nasogastric tube was inserted orally in all patients after the induction of anesthesia, and the stomach was then emptied. At the end of anesthesia, residual neuromuscular block was antagonized with glycopyrrolate 0.4 mg and pyridostigmine 10 mg IV.
In the recovery room, analgesia was begun after an initial dose of fentanyl 50 μg and ketorolac 30 mg IV in all patients. The patient-controlled analgesia (PCA) device was programmed to allow 1 mL/h as a basal infusion and a 2-mL bolus with a lockout interval of 10 min; it contained fentanyl 10.8 μg/mL and ketorolac 3 mg/mL with IV saline (total volume, 60 mL). Most patients felt comfortable after this pain medication. However, if analgesia was judged to be inadequate by the patient, the midwife, or the medical staff, the study was stopped and alternative analgesia given. Pain scores were not measured in this investigation.
Vomiting, including retching, and other adverse side effects were assessed at 8 and 24 h after surgery by an independent observer who was unaware of the patient randomization and of PAS treatment. Vomiting was defined as forceful expulsion of gastric contents from the mouth. Retching was defined as an active attempt to vomit without expulsion of gastric contents. Metoclopramide 10 mg 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. The total amount of fentanyl consumption during the first 24 h after surgery was recorded at the end of the study period.
Nonparametric data (nausea, yes/no; vomiting, yes/no; antiemetic rescue, yes/no) were analyzed by using Fisher’s exact test. A series of one-way analyses of variance was conducted to examine differences among the three groups with respect to parametric variables. If a significant difference was found, a comparison was conducted with Tukey’s significant difference test. A P value of <0.05 was considered significant.
There were no statistical differences among study groups with respect to age, weight, height, or duration of anesthesia (Table 1). During the 8 and 24 h after surgery, the incidence of PONV was significantly reduced compared with the control group when PAS was applied at the K-D2 or P6 point (P < 0.001); however, there was no difference between the K-D2 and P6 groups (Table 2). All groups experienced the most PONV during the 8-h postoperative follow-up period.
The need for rescue antiemetics was significantly less in the treatment groups compared to the control group (P < 0.001). There was no significant difference among the groups in the amount of fentanyl consumption.
Our study of 160 patients demonstrated that PAS at the K-D2 can indeed significantly reduce PONV, as can PAS at the P6 point, compared with the control group after abdominal hysterectomy (P < 0.001). Yoo (15) discovered and studied KHT, which originated from the theory that all internal organs are represented reflexively in the hands. Stimulating the proper points (KHAP) in the hands can control all of the functions of human organs. An estimated two million Koreans have experienced KHT and can attest to the effectiveness of this method of treatment. However, KHAP is rarely applied in Western medicine. Few data concerning its antiemetic effect have been published.
PAS is noninvasive, simple, painless, and easy to apply at the correct point. However, acupuncture is invasive and unpleasant. Noninvasive acupressure could be applied for longer durations than invasive acupuncture techniques. The cost of either acupressure (approximately $8.00) (12) or a transcutaneous acupoint electrical device (ReliefBand®) ($30) (16) is more expensive than PAS (1$ per five sheets). PAS is easy to use and requires no special training; it is a good alternative to routinely prescribed antiemetics and nonpharmacologic techniques for the treatment of PONV. Moreover, the size (5 × 5 mm2) of PAS is convenient, and it is available for 8–12 hours because of the capsicum element (14).
The correct timing and accurate localization of acupuncture and acupressure at P6 further improved the reduction of PONV (7,11,12). P6 had no antiemetic effect when opioids had been administered previously. Once the trigger zone in the brain was sensitized by IV or inhaled anesthetics, it was difficult to overcome or desensitized it by the stimulation of P6. Therefore, the stimulation of P6, performed before the induction of anesthesia, produced antiemetic effects (11). To achieve a satisfactory antiemetic effect, we also applied PAS to the treatment points before the induction of anesthesia.
The mechanism by which PAS at K-D2 achieves its antiemetic effect is not yet fully understood. Topically applied capsaicin induces a specific blockade of transport and synthesis of substance P from sensory C fibers. As a result, applications of capsaicin are suitable for the treatment of neuropathic pain or musculoskeletal disorders, with or without inflammatory components (17). PAS has an effect similar to that of acupressure or acupuncture, which stimulates the right place (14). The hemokinesis (blood flow) of the trigger zone in the brain is improved and the trigger zone is desensitized by a neurochemical substance induced by capsaicin stimulating the K-D2 hand point (15), which might prevent the PONV caused by IV or inhaled anesthetics. The nature of this neurochemical substance has not yet been elucidated.
Prior systemic treatment with capsaicin, which defunctionalized both spinal and vagal capsaicin-sensitive afferent nerves, abolished the inhibitory effect of ethanol on the gastrointestinal tract in rats (18) and inhibited gastric acid secretion, which induced gastric dysrhythmia and nausea (19). We also suggest that the ingredients of capsaicin may reduce PONV.
Nausea and vomiting are frequent adverse effects of PCA with opioids. With opioid PCA plus placebo, the incidence of nausea and vomiting is approximately 50%(20). The 56.7% incidence of PONV after hysterectomy in our study was similar to that in other studies (9,12). The incidence of PONV was more evident after 8 hours than after 24 hours after surgery, because PONV either was reduced as recovery progressed or decreased with the elimination of anesthetic drugs.
In a study by Fassoulaki et al. (9), transcutaneous electrical nerve stimulation was applied at the P6 point and continued for six hours after surgery. The difference in the incidence of vomiting was more evident six hours after surgery; however, it did not continue during the follow-up period. Although P6 manual acupuncture was an effective antiemetic in patients having cancer chemotherapy, because of the time involved and the brevity of the action (eight hours), electroacupuncture was the adopted clinical technique (21). In this study, PAS was applied at the treatment point at least 30 min before the induction of anesthesia and continued for eight hours after surgery. Pharmacological therapy with drugs such as ondansetron, droperidol, and metoclopramide is often associated with side effects such as sedation, anxiety, restlessness, diarrhea, abnormal muscle movements, and headache. The overall risk of adverse effects did not differ (22). Further study is required to assess whether the PAS method will be an alternative to antiemetics, electroacupuncture, or acupressure for patients receiving cancer chemotherapy.
The incidence of the need for rescue antiemetic drugs in the treatment groups was significantly less frequent than in the control group (P < 0.001). We suggest that PAS may reduce both nausea and vomiting, which require rescue antiemetics. Fentanyl consumption was similar in the treatment and control groups. Our results suggested that PAS at either K-D2 or P6 did not produce postoperative analgesia.
It is virtually impossible to design a truly double-blinded, placebo-controlled study when investigating nonpharmacologic therapeutic techniques such as acupressure (23). However, an important aspect of our study is that it was double-blinded and placebo controlled. Consequently, neither the patients nor the evaluating physicians were aware of the treatment status. This is a key element of the study design, because placebo effects in PAS can be substantial.
In conclusion, the PAS method allied with either the K-D2 or the P6 point is a simple, inexpensive, and effective method for preventing PONV.
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© 2002 International Anesthesia Research Society
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