At present, both preoperative psychological preparation programs1–4 and pharmacological interventions, such as midazolam, are reported to be effective for the management of preoperative anxiety in children.5–8 However, both these modalities have several limitations. For example, preoperative preparation programs are expensive and require time and trained individuals.9 Similarly, administration of oral midazolam may delay postanesthesia care unit (PACU) discharge after short procedures such as gastrointestinal endoscopy.10,11 Thus, nonpharmacological interventions, such as acupuncture and related interventions, are evaluated as alternative modalities for the management of preoperative anxiety in children.
Previously, our group has reported that acupuncture and related techniques are effective for the treatment of anxiety in adult volunteers, adult surgical outpatients and parents of children undergoing surgery.12–15 Furthermore, several recent investigations involving adult volunteers and patients report that acupressure administrated at Extra-1* point applying direct circular motion with thumb pressure (about 3 × 105 PA) reduced verbal stress scores and induced hypnotic effects as measured by a Bispectral Index (BIS) monitor.16–18 Since acupressure is a noninvasive stimulation technique applied to an acupuncture point, we submit that it is likely to be more appealing to children than a technique involving needles. It is important to note, however, that there are several acupressure techniques that can be used in clinical settings. Acupressure can be applied by direct finger pressure with or without circular motion16–18 or with constant pressure resulting from the application of a bead/pellet over a targeted acupuncture point.15,19 The latter described technique is obviously less labor-intensive and may thus have obvious advantages in the clinical perioperative settings.
In view of the findings of previous adult studies involving acupressure and anxiety coupled with the advantages of acupressure over acupuncture in children undergoing surgery, we designed a study to examine if acupressure at the Extra-1 acupoint is effective in reducing preprocedural anxiety and producing hypnotic effects.
Children between the ages of 8 and 17, classified as ASA Physical Status (I-II), who were scheduled to receive general anesthesia for gastrointestinal endoscopic procedures, were enrolled to this randomized, controlled trial. All children and parents spoke fluent English and none of the children had any reported developmental delays. The Yale University IRB has approved the study protocol; an informed consent was obtained from all parents and an assent was obtained from all children who participated in this study (please refer to study protocol for consent procedures).
Acupressure interventions in this study were delivered using an acupressure-bead (Acu-pellet; Helio, San Jose, CA) attached to a self-adhesive tape that secured the bead in place and created continuous standardized pressure of 1.3 psi as measured by a tonometer (Fig. 1). The use of a self-adhesive pressure bead is a widely used technique to create continuous acupressure and avoid the need for additional manipulation once the beads are placed.15,19 The acupuncturist (SMW) applied acupressure beads to the two intervention groups based on a random computer-generated assignment. In order to prevent any possible bias, all participants were informed that the aim of this study was to determine “which acupoint on the forehead is more effective in reducing preoperative anxiety” The groups included:
- Ex-1 Group. Intervention applied at the Extra-1 acupoint, which is located in the midpoint between the eyebrows.15
- Sham Group. Intervention applied above the lateral boarder of the left eyebrow. This widely used sham point was selected as it has the same dermatomal distribution as Extra-1 and does not result in any reported clinical effects.15
After institutional Human Investigation Committee approval, all children who fulfilled the above criteria were invited to participate in the study by a gastroenterologist (SE) during an office visit. On the day of the procedure, and after completion of all the routine admitting processes, the child and his/her parents were asked again by a research assistant, if they would like to participate in the study. The consent and assent stated that the researchers intend to test acupressure to two acupoints on the forehead that may reduce preprocedural anxiety. After enrollment, demographic data were obtained and a baseline self-reported anxiety questionnaire was completed. This anxiety questionnaire, the State Trait Anxiety Inventory for Children (STAIC), is considered the “gold standard” for the assessment of anxiety in children older than 6 yr.20 This scale, consisting of two parts, is designed to measure both state anxiety (i.e., anxiety changes in response to an acute condition-STAIC state anxiety scale) and trait anxiety (i.e., chronic, pervasive anxiety-STAIC trait anxiety scale).20 This questionnaire is well validated and has been used in more than 1000 studies.21
Once baseline anxiety assessment was completed, a disposable pediatric BIS sensor was placed on each child’s forehead. This sensor was attached to a BIS 2000 Monitor (Aspect Medical Systems Inc, Newton, MA). After a 5-min period to allow the stabilization of the BIS 2000 monitor, the acupuncturist (SMW) applied the intervention based on group assignment without the presence of a research assistant or member of the nursing staff. Thirty minutes after the placement of the acupressure bead, the research assistant returned to administer a second state anxiety scale to the child (STAIC-state anxiety) in the holding area. In order to eliminate any confounding variables the study protocol did not allow the administration of preprocedural sedative medication or the presence of parents during the induction of anesthesia.
Children were then brought into the operating rooms. A standardized single breath vital capacity inhaled technique (with mixture of 70% N2O/O2 and 7% Sevoflurane) was commenced through a scented mask.22,23
After the establishment of an IV catheter, an anesthesiologist intubated the tracheas of all children, sevoflurane was discontinued and general anesthesia was maintained using a 70% nitrous/oxygen mixture and a propofol infusion. No narcotic drugs were administered during the procedure. The propofol infusion rate was titrated to maintain the BIS number in the range of 40 to 60. Propofol consumption was expressed as the total propofol amount used during the procedure divided by body weight and duration of the procedure. No other anesthetic or sedative drugs were administered to any of the participants in this study. The propofol infusion was terminated at the completion of the procedure and the acupuncturist was then called to remove the acupressure bead. We also documented the time interval from discontinuation of the propofol infusion until the time for tracheal extubation (time to awake).
Patients were then transported to the PACU, and the nursing staff provided routine recovery care. IV fentanyl (0.5 μg/kg) was administrated for a visual analog scale score of 4 and above. Ondansetron 0.1 mg/kg (maximum dose 4 mg) was administered for vomiting or nausea that lasted more than 10 min. The incidence of pain, nausea, and vomiting was documented.
Only the acupuncturist knew the group assignment. All other personnel, including research assistants, pediatric gastroenterologists, anesthesiologists, and nursing staff, were blinded to the study group. These individuals were told that the purpose of this study was to test which acupoint is more effective for the management of preoperative anxiety and intraoperative propofol requirements. Further, the acupuncturist was not involved in the anesthetic management of patients or in any other aspect of the study.
The primary outcome of this study was the change in the child’s anxiety levels in the preprocedural area from baseline to 30 min after the acupressure intervention. Secondary outcomes included changes in BIS during the preprocedural period and changes in propofol requirements during the gastrointestinal procedure. Sample size for the primary outcome was calculated before based on findings from a previous study.15 Considering a repeated measures design, a medium effect size, an alfa of 0.05 and power of 85%, 26 patients were needed in each study group. Randomization was done with a computer-based random number generator and was stratified based on age, gender, and procedure. All data were imported into a SPSS version 11.0 (SPSS Inc, Chicago, IL). Baseline characteristics, and PACU recovery profile were analyzed using Student’s t-test. Two-way repeated measure analysis of variance was used to analyze changes in state anxiety and average BIS values over time. Average BIS values were calculated for each five minute segments of continuous BIS data, as directly downloaded from the BIS monitor. The Mann-Whitney test was performed for nonparametric data such as propofol consumption. P < 0.05 is considered significant.
Fifty-two children were enrolled in this randomized, controlled trial. No differences between study groups were found in any of the demographic or other baseline variables (Table 1).
State anxiety levels of the two study groups differed over time, as evidenced by a significant group X time interaction (F = 6.1, P = 0.017). That is, although at baseline, the state anxiety of children did not differ between the two groups (P = 0.58). Thirty minutes after the application of acupressure, children in the Ex-1 group experienced a reduction of anxiety whereas children in the sham group experienced an increase in anxiety expressed as mean (range) (−9% [−3 to −15] vs 2% [−6 to 7.4], P = 0.012) (Fig. 2). Throughout the preprocedural waiting period, the average BIS was not significantly different between study groups (95 ± 3 vs 96 ± 3, P = 0.49).
The amount of propofol needed to maintain a BIS value of 40–60 during the endoscopic procedure was not different between the Ex-1 and sham groups (214 ± 76 μg · kg−1 · min−1 vs 229 ± 95 μg · kg−1 · min−1, P = 0.52). Also, the intraprocedural average BIS value was similar between groups (45 ± 8 vs 45 ± 8, P = 0.81).
“Time to awake” and incidence of nausea and vomiting in the PACU were not different between Ex-1 and sham groups. The results are summarized in Table 2.
In children undergoing endoscopies, we found that acupressure with a self-adhesive pressure bead at Extra-1 acupoint decreases preprocedural anxiety but does not affect the preprocedural BIS value. In addition, we noted that the continued application of this acupressure intervention throughout the entire endoscopic procedure, whereas controlling for BIS levels, did not affect the patient’s total propofol requirements for the procedure.
Adult studies by Fassoulaki et al. and Agarwal et al. have indicated that acupressure at Extra-1 acupoint decreases both verbal stress scores and BIS values.16–18 Indeed, this was one of the impetuses for this study. In contrast to these previous adult studies, we found no effects of acupressure delivered via the self-adhesive bead/pellet at the Extra-1 acupoint on BIS of children prior to surgery. This finding is consistent with our previous findings.15 The differences between Fassoulaki et al. and Agarwal et al. with our study is that Fassoulaki et al. and Agarwal et al. used direct finger pressure with circular motion whereas we used a self-adhesive acupressure bead with constant pressure. Differences in the results may be related to the differences in the acupressure stimulation techniques used.
Lack of group differences with regard to intraprocedural propofol consumption should be viewed in light of three previous studies. In a study of adult patients, Maranets and Kain noted that only higher trait anxiety (but not state anxiety) resulted in higher propofol requirements for maintenance of anesthesia.24 Thus it is not surprising that in this study reduction of preprocedural state anxiety did not result in reduced intraprocedural propofol requirements. Further, it is possible that intraprocedural effects of acupressure were suppressed by propofol general anesthesia. Indeed, a previous functional magnetic resonance imaging study by our laboratory indicated that acupuncture-induced blood oxygen level-dependent signals were suppressed by propofol general anesthesia.25 A similar observation was seen using an auditory evoked index monitor. Lu et al. noted that electroacupuncture enhances the sedative effect of propofol in a target plasma concentration of 1.5 μg/mL but not at 2.0 μg/mL.26
This study has a few limitations. We recognize that age, gender, and procedures may affect how a child responds to an acupressure intervention and therefore patients were randomized and stratified based on these variables. We did not, however, stratify patients based on their disease process. Consequently, we cannot exclude the fact that certain patients may have been more or less susceptible to acupressure, i.e., patients with chronic abdominal pain with no etiology compared to patients with inflammatory bowel disease. We have used a sham-control study design in order determine the specific effect of the particular acupuncture point studied. The use of an inert placebo in the settings of randomized, controlled trials is essential for both pharmacological and nonpharmacological clinical studies27 and a no-treatment control group in the setting of acupuncture or any clinical trial is highly problematic.27 In our study, we made the choice not to use a no-treatment control group for two reasons: (a) A no-treatment control group prevents blinding of the treatment, and (b) when nontreatment controls are used, the sham group controls for the possibility of a placebo effect. A review of the literature reveals that contemporary, carefully designed acupuncture studies typically use sham-control rather than no-treatment control. We believe that only points or techniques that have been shown to be ineffective or less effective should be used as sham control. Therefore, we have chosen the same sham point with the same acupressure stimulation that was found to be less effective than acupressure on Extra-1 acupoint in a previous study.15 Finally, a question can be raised as to whether the 11% difference in state anxiety between the two groups of children after the assigned intervention(s) is considered clinically significant. We submit that the answer depends on variables such as the instrument used for assessment of anxiety and the level of child expectation. Although there are no data regarding this issue of clinical significance in the pediatric anxiety literature, we did identify two adult publications that indicate that a minimum of 10% difference in the state anxiety level as assessed by the State Trait anxiety scale for adults is considered clinically significant.28,29 The state anxiety assessment tool used in this present study is the pediatric version of the instrument used in the above publications (STAIC). Therefore, we believe that the difference of 11% should be considered clinically significant.
We conclude that although bead-generated acupressure applied preprocedurally at Extra-1 acupoint decreases preprocedural anxiety in children undergoing general anesthesia for gastrointestinal endoscopies, it did not affect the consumption of propofol during the intraprocedural period. More research is needed to determine whether the hypnotic effects of Extra-1 acupoint are related to the specific acupressure technique used.
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*Extra-1 acupoint: This acupuncture point is also known as “Yin-Tang” acupoint in Traditional Chinese Acupuncture textbooks. The location of Yin-Tang is in the vicinity of three major meridians (Du, UB and SI) and one extra-meridian Yang Qiao and all these meridians are believed to be connected to one another. As a result, Yin-Tang serves as the “window” of heart yang (Essentials of Chinese Acupuncture. Foreign Languages Press, Beijing, China, 1993). Stimulation on Yin-Tang acupoint is also used to treat insomnia.