Acupuncture or acupressure at the Nei-Guan (P.6) point on the wrist produces antiemetic effects in awake but not anesthetized patients. The authors studied whether a combined approach using preoperative acupressure and intra- and postoperative acupuncture can prevent emesis following tonsillectomy in children.
Patients 2-12 yr of age were randomly assigned to study or placebo groups. Two Acubands with (study) and two without (placebo) spherical beads were applied bilaterally on the P.6 points; non-bead- and bead-containing Acubands, respectively, were applied on the sham points. All Acubands were applied before any drug administration. After anesthetic induction, acupuncture needles were substituted for the beads and remained in situ until the next day. All points were covered with opaque tape to prevent study group identification. A uniform anesthetic technique was used; postoperative pain was managed initially with morphine and later with acetaminophen and codeine. Emesis, defined as retching or vomiting, was assessed postoperatively. Ondansetron was administered only after two emetic episodes at least 2 min apart. Droperidol was added if emesis persisted.
One hundred patients were enrolled in the study. There were no differences in age, weight, follow-up duration, or perioperative opioid administration between groups. Retching occurred in 26% of the study patients and in 28% of the placebo patients; 51 and 55%, respectively, vomited; and 60 and 59%, respectively, did either. There were no significant differences between the groups. Redness occurred in 8.5% of acupuncture sites.
Perioperative acupressure and acupuncture did not diminish emesis in children following tonsillectomy.
POSTOPERATIVE nausea and vomiting (PONV) is a well-recognized problem in pediatric patients after tonsillectomy, with an incidence from 40% to 70%. [1–3] It is uncomfortable [4,5] and may be associated with complications such as bleeding, dehydration, [5,6] electrolyte [6] and acid-base [5] imbalance, and pulmonary aspiration. [6] It may prolong the stay in the postanesthesia care unit, [4] delay discharge, [2,4,6–8] and increase hospital admission rate. [9,10]
Various medications decrease but do not eliminate PONV. Moreover, their use may be associated with a variety of side effects [6,11–14] and high cost. [4] This has lead to the reexamination of nonpharmacologic techniques for the prevention of PONV. [4,6,15] The usefulness of acupuncture to treat PONV has been noted by the National Institutes of Health. [16]
A recent meta-analysis indicates that the antiemetic effect of acupuncture requires treatment of awake rather than anesthetized patients. [15] Since non-anesthetized children are often reluctant to undergo insertion of acupuncture needles, we studied the effectiveness of acupressure before and acupuncture after anesthetic induction and during the postoperative period in children undergoing tonsillectomy.
Methods
The study was approved by the Children's Hospital clinical investigation committee, and written informed parental consent was obtained. Subjects were 2–12 yr of age scheduled for elective tonsillectomy, with or without adenoidectomy or other minor procedures. Patients were randomly assigned to study or placebo control groups. Exclusion criteria included congenital heart disease or significant pulmonary disease, predisposition for emesis or actual emesis in the 24 h before surgery, use of medications with antiemetic effects within the 24 h before surgery, infection over an acupuncture point, need for postoperative intubation for more than 1 h, and severe obstructive sleep apnea.
Acupressure and Acupuncture Protocol
Acupressure and acupuncture were applied to the patients' forearms at the Nei-Guan (P.6) treatment point [17,18] in the study group and at the sham point in the control group (Figure 1). The P.6 point is located between the flexor carpi radialis and the palmaris longus tendons, one sixth of the distance between the distal transverse crease of the wrist and the cubital crease, and is specifically designated in traditional Asian medicine for the treatment of nausea and vomiting. [18,19] The sham point was located in the center of the dorsomedial aspect of the forearm, where no known acupressure or acupuncture point or meridian pathway is located. The location of all four points was delineated by a single investigator in 95% of the patients. Acupressure and acupuncture were performed by four anesthesiologists trained by a licensed acupuncturist who did not assess PONV.
Figure 1. (A) The P.6 point on the forearm of a child. (B) Forearm of a child with Acubands at the P.6 and sham points.
Figure 1. (A) The P.6 point on the forearm of a child. (B) Forearm of a child with Acubands at the P.6 and sham points.
Acubands (Lifestyle Enterprises, Little Silver, NJ) were used for acupressure and consist of an adjustable strap with a spherical bead. Two Acubands with (study group) or two without (placebo group) beads were applied bilaterally on the P.6 points; non-bead- and bead-containing Acubands, respectively, were applied on the sham points. All Acubands were applied before premedication (Table 1). Immediately after anesthetic induction and before glycopyrrolate or morphine administration, all Acubands were removed and acupuncture intradermal needles (Seirin America, Weymouth, MA; length, 3 mm; diameter < 30 gauge) were substituted for the beads. All four points were covered by opaque adhesive tape to prevent identification of group assignment. The needles were removed at the end of the study period.
Preoperative Preparation
Diet was unrestricted until midnight, and clear fluids were allowed up to 3 h before anesthetic induction. Midazolam (0.5–1.0 mg/kg) and acetaminophen (10–20 mg/kg) were administered orally in the immediate preoperative period. Upon patient refusal to swallow or the preference of the anesthesiologist, intravenous midazolam (30–100 [micro sign]g/kg) and rectal acetaminophen (10–20 mg/kg) were administered immediately after anesthetic induction. No prophylactic antiemetics were administered perioperatively.
Anesthetic Management
Anesthesia was induced with either intravenous thiopental (5–7 mg/kg) or inhalation of up to 8% sevoflurane with a nitrous oxide-oxygen mixture (ratio between 1:1 and 3:1). Neuromuscular blockade was achieved with cisatracurium (50–150 [micro sign]g/kg). Glycopyrrolate (10 [micro sign]g/kg) and morphine (100 [micro sign]g/kg) were administered intravenously immediately before orotracheal intubation. Anesthesia was maintained with isoflurane (inspired concentration 0.2–2%) in a nitrous oxide-oxygen mixture (3:1–3:2). Fentanyl (1 to 2 [micro sign]g/kg) was administered intravenously during the operation at the discretion of the anesthesiologist. At the end of surgery, neuromuscular blockade was antagonized with neostigmine (35–70 [micro sign]g/kg) and atropine (15–30 [micro sign]g/kg) intravenously, and an orogastric tube was inserted, suctioned, and removed.
Postoperative Care
Postoperative pain was managed with intravenous morphine (50 [micro sign]g/kg, repeated as necessary) in the post-anesthesia care unit, and with oral codeine (0.5–1.0 mg/kg up to every 3–6 h) and acetaminophen (10–20 mg/kg up to every 4–6 h) on the ward. Oral intake was restricted to cold, clear liquids during the first 2 h postoperatively and then to a cold, soft diet. Postanesthesia care unit and ward nurses who assessed and charted postoperative emesis and medication administration were blinded to the group assignment of each patient.
Definitions of Postoperative Nausea and Vomiting
Vomiting was defined as the forceful expulsion of gastric contents from the mouth. Retching was defined as an active attempt at vomiting without expulsion of gastric contents. [6] Emesis was defined as either retching or vomiting. [20] Repeated episodes occurring within 2 min were considered a single episode. Rescue antiemetic treatment (ondansetron, 150 [micro sign]g/kg up to 4 mg every 6 h) was administered if two or more emetic episodes occurred. If emesis persisted, droperidol (15 [micro sign]g/kg, up to every 6 h) was added intravenously.
Data Collection
Age, gender, American Society of Anesthesiologists physical status, previous PONV (graded as none, mild, moderate, or severe, as judged by the parents), method of anesthetic induction, duration of anesthesia, frequencies and dosages of perioperative medications (opioids, corticosteroids, and antiemetics), follow-up duration (from arrival at the postanesthesia care unit until acupuncture needle removal), emetic episodes, and acupuncture-related adverse effects were recorded.
Statistical Analysis
Assuming a 70% PONV rate after tonsillectomy, [3,7] a sample size of 47 patients per group is sufficient to provide 90% power to detect a 50% reduction in the proportion of affected patients (Fisher exact test with a two-tailed [Greek small letter alpha] error of 0.05). Two-sample t tests were used to compare continuous variables between treatment groups and fasting duration (separately for liquids and solids) between patients who did or did not experience retching, vomiting, or either. Two-tailed Fisher exact tests were used to compare categoric parameters between the treatment groups and between genders, and to compare the severity of previous PONV with the occurrence of retching or vomiting. Mann-Whitney U tests were used to compare the number of retching, vomiting, and emetic episodes among patients and the rate of these episodes between genders. To correct for possible confounding effects of dexamethasone administration, the incidence of vomiting, retching, or either was evaluated using multiple logistic regression with dexamethasone and treatment as binary predictors. Differences were considered statistically significant at P < 0.05. Power calculation was performed using nQuery Advisor 2.0 (Statistical Solutions, Boston, MA) and data analysis using Statistical Analysis Software (SAS) 6.12 (SAS Institute, Cary, NC).
Results
Forty-seven patients were included in the study group and 53 in the placebo group. There were no differences between the groups with regard to demographics or previous retching, vomiting, or either (Table 2). Perioperative medications and postoperative emesis are shown in Table 3 and Table 4. The study group experienced a greater frequency of vomiting than the placebo group (P = 0.046). There was no difference in rescue antiemetic usage. Multiple logistic regression indicated that, although dexamethasone was associated with a decreased incidence of vomiting (P = 0.002), retching (P = 0.038), and emesis (P = 0.002), acupressure and acupuncture had no effect (all P values > 0.65).
Improper drug administration occurred in nine patients, including a higher intraoperative morphine dose (two patients), no midazolam administration (three), sevoflurane administration for anesthetic maintenance (two), propofol bolus for induction (one patient in the study group, who eventually vomited), and flumazenil administration (one patient). Six patients were followed for less than 12 h. When the data from these 15 patients were excluded from statistical analysis, the difference in gender, dexamethasone administration, and the number of vomiting episodes no longer existed. There was no change in any other statistical outcome. Therefore, the entire sample size was used for all analyses. A history of previous PONV was not related to current retching, vomiting, or either, nor was there a difference between genders. Fasting for solids but not for liquids was longer in those who experienced emesis (14.8 +/- 2.2 versus 13.5 +/- 2.7 h, P = 0.011) and in those who experienced vomiting (14.8 +/- 2.1 versus 13.6 +/- 2.7 h, P = 0.014).
Complications attributed to acupressure/acupuncture are presented in Table 4. Puncture site redness was mild in all cases, and irritation at a single point necessitated early removal of the needle. No other complications were detected.
Discussion
Acupuncture is an Asian medical treatment that has been practiced for more than 3,000 years and has been used to prevent emesis in various settings including the postoperative period. [4,15,16] Its simplicity, lack of major side effects, and low cost may offer advantages over modern therapies. Its mechanism of action is not fully understood; placebo-effect, psychologic, or physiologic (neurochemical substance release) factors may play a role. [17] Although the traditional form of acupuncture involves needle insertion, variations have evolved that apply external pressure on specified skin points (acupressure), electrical stimulation via needles, and other cutaneous or transcutaneous stimulation modes.
The antiemetic effectiveness of acupuncture or acupressure at the P.6 point has been shown in some, [15,17,21–28] but not all [15,29–32] trials. In a comprehensive review of previous studies [15] and in a subsequent study [29] in which stimulation of the P.6 point was performed during general anesthesia, no significant beneficial effect on PONV was shown. Three of these studies involved children. [29–31] When P.6 stimulation was used to prevent PONV in awake patients, all seven trials involving adults [21–27] showed beneficial effects, whereas the single pediatric trial [32] showed no beneficial effect. However, many previous studies, including the pediatric trials, [29–32] suffer from methodologic problems, including (1) lack of a true placebo group, since there was no sham point stimulation [17,22,23,25–30,32];(2) single-blind studies during which patients could be aware of a stimulation versus no stimulation [22,23,25–28,32];(3) a short follow-up period [21,22,24,26,32]; or (4) no standard premedication, [26,27] anesthetic technique, [22,23,27] or postoperative pain control. [21,24,27] Inasmuch as an awake state may be necessary to achieve beneficial acupressure and acupuncture effects [15] and since many nonanesthetized children are reluctant to undergo acupuncture needle insertion, we developed a model that combined pre-anesthetic P.6 acupressure stimulation with a painless intra- and postoperative acupuncture stimulation technique. Unfortunately, this combination did not reduce the incidence of emesis or the need for antiemetic rescue medications after tonsillectomy.
Factors other than acupuncture may potentially affect the results. The shorter fasting period for clear liquids in the study versus placebo groups probably had no clinical importance, since no patient had a historical predisposition for emesis and the avoidance of any solid intake at least 8 h before surgery should suffice for gastric emptying. Also, no difference was found in the duration of preoperative fasting for clear liquids between patients who did and did not experience emesis. The higher rate of perioperative dexamethasone administration in the study patients could have decreased emesis, [2,6] and the higher proportion of females could have increased emesis in the placebo patients. [6,33,34] The similarity in the incidence of emesis could lead to a conclusion that the sham point stimulation, rather than the "true" acupuncture, decreased postoperative emesis, or that P.6 stimulation has an emetic effect. However, there are no known meridian pathways at the sham point used in this study. Moreover, in contrast to other studies [33,34] we found no gender effect on the occurrence and rate of emesis, possibly because of the young (premenarchal) age of our patients. Furthermore, multiple logistic regression indicated that after accounting for the effect of dexamethasone, acupressure and acupuncture still had no significant effect. Finally, the difference in gender and in perioperative dexamethasone administration between the groups no longer existed after excluding data from the 15 patients in whom protocol deviations occurred. Therefore, these possible factors apparently did not significantly influence our results.
In conclusion, a combination of acupressure before and acupuncture after anesthetic induction was ineffective for the prevention of PONV after tonsillectomy in children. Further studies may reveal whether modifying the technique of acupressure and/or acupuncture can be helpful in this situation.
The authors thank the patients and families who participated in this study; all the nurses, otolaryngologists, and anesthesiologists who assisted in its performance; and, in particular, David Eisenberg, M.D., from the Center for Alternative Medicine Research at the Beth Israel-Deaconess Medical Center, for his help in study design.
