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REGIONAL ANESTHESIA: Research Report

Pressure Applied on the Extra 1 Acupuncture Point Reduces Bispectral Index Values and Stress in Volunteers

Fassoulaki, Argyro MD, PhD, DEAA*,; Paraskeva, Adia MD†,; Patris, Konstantinos MD†,; Pourgiezi, Theodora MD*,; Kostopanagiotou, Georgia MD*

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doi: 10.1213/01.ANE.0000048713.41657.D3
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Abstract

Preoperative stress and anxiety may affect intraoperative anesthetic requirements and a smooth recovery (1–3). Anxiolytic and sedative drugs such as benzodiazepines, antihistamines, or α2-adrenergic agonists in ambulatory patients may prolong recovery and postoperative sedation and, therefore, the time to discharge from the hospital.

Nonpharmacological interventions such as acupuncture using the traditional acupuncture needles or transcutaneous electrical stimulation of certain acupuncture points have been used to manage acute and chronic pain as well as to control postoperative nausea and vomiting (3–10). However, the evidence of such interventions to alleviate anxiety before surgery is limited (11). An acupuncture extraordinary point, the “extra 1” point or Yintang point, when stimulated provides relief from stress (12). This point, when punctured subcutaneously 1–1.5 cm in an oblique caudal direction, may alleviate insomnia. The aim of the present study was to investigate the effect of pressure applied on the acupuncture extra 1 point on the bispectral index (BIS) values and on the stress and tension of volunteers of both sexes.

Methods

After obtaining approval from the local ethics committee, 25 volunteers who were ASA physical status I–II, nonsmokers, and of both sexes gave their consent to participate in the study. No one was taking sedatives, analgesics, or other drugs, was exposed to acupuncture, or believed in traditional Chinese medicine.

All measurements were performed during morning hours. Each volunteer received pressure on an acupuncture point, the extra 1 point, and on a control point in a randomized manner and on different days. An anesthetic nurse tossed a coin, and each individual was randomized to receive pressure on the acupuncture point first for heads and on the control point first for tails. Each volunteer was lying comfortably in an armchair in semi-sitting position and in a quiet environment. At this point, the volunteer was asked to score the stress and tension that he or she had based on a verbal stress scale (VSS) from 0 (no stress) to 10 (the maximum stress). Then, a Zipprep™ electrode (Aspect Medical Systems, Inc., Newton, MA) was attached, as described in previous studies (13,14), and a period of 5 min was allowed for each volunteer to obtain stable BIS values. Baseline values were derived from recording three individual BIS values.

The acupuncture extra 1 point is located midway between the medial ends of the two eyebrows at the root of the nose (Fig. 1). The pressure on this point was applied by the thumb for 10 min while performing circular movements every 20–25 min−1. The control point was located 2 cm from the lateral end of the left eyebrow (Fig. 2). The duration of pressure on the control point was limited to 5 min because volunteers found it to be an unpleasant feeling. We tried a control point close to the BIS sensor so that possible interference of pressure application with the BIS sensor and signal would be observed in both treatment and control points. At the end of each 30-s period, of the 3 consecutive BIS values read, we recorded the median value. When the 10- or 5-min time of pressure application was completed, the thumb was removed. The volunteer remained in the same position, and, in the case of the extra 1 point, BIS values were similarly recorded for 3 min. The average of these values comprised the BIS values after release of pressure. On a different day, and in an order determined by the method of randomization, the same volunteers were exposed to pressure applied similarly either on the extra 1 point or on the control.

Figure 1
Figure 1:
Pressure application on the extra 1 point.
Figure 2
Figure 2:
Pressure application on the control point.

When the extra 1 point or the control point was released, and after having completed the BIS mea-surements, each volunteer was asked to score again his or her stress, tension, and anxiety from 0 to 10. The score values were also recorded. Readings and recording of BIS values and recordings of VSS were performed by an anesthesiologist who stayed with the BIS apparatus behind a screen and was not watching the volunteer or the procedure of pressure application.

A pilot study with eight patients yielded VSS mean (sd) scores of 6.8 (1.7) before and 2.7 (2.1) after treatment. Assuming a sd of 2, including 15 patients in the group, achieves 94% power (β = 0.06) to detect a difference of 2 between the VSS scores and a 99% power to detect a difference of 3 at a significance level α of 0.05. With the same sd, a sample size of 15 achieves 80% power to detect a mean difference of 2 between the VSS scores and 99% power to detect a difference of 3 at a significance level of 0.01.

Demographic data are given by descriptive statistics. Cohortization of BIS values recorded during pressure application on the extra 1 point and the control point was performed for each 2.5-min intervals.

Because most of the BIS and VSS did not follow normal distribution, we applied nonparametric statistics for BIS and for VSS comparisons.

Friedman test was used to analyze the BIS values obtained before, during pressure application on the extra 1 point for 2.5, 5.0, 7.5, and 10 min, and after pressure release. Similarly, the Friedman test was used to compare the BIS baseline values and the values obtained after pressure application on the control point for 2.5 and 5.0 min. The paired comparisons regarding the extra 1 point and BIS values at different time points were performed with Wilcoxon rank sum test. Similarly, the Wilcoxon rank sum test was used for the paired comparisons of the BIS baseline values and values after pressure application on the control point for 2.5 and 5.0 min. The BIS values recorded before 2.5 and 5.0 min after pressure on the extra 1 point were compared with those obtained at the same time points on the control point with the Mann-Whitney test. The VSS values before versus after pressure application for each point were compared with the Wilcoxon rank test. For the VSS comparisons between the extra 1 and the control point before pressure application, as well as after pressure application, we also used the Mann-Whitney test.

Results

Demographics of the volunteers (mean ± sd) are as follows: age, 37 ± 8.2 yr; body weight, 66 ± 12.2 kg; and height, 167 ± 9.5 cm. Of the 25 volunteers, 4 were men, and 21 were women. Twelve volunteers received acupressure first on the extra 1 point and 13 on the control point. To exclude the possibility of a treatment-period interaction, we compared the BIS and VSS values recorded for those volunteers who received first the extra 1 point acupressure to the BIS and VSS values of the volunteers who were treated inversely. The sequence of acupressure application did not impact the BIS and VSS values.

The Friedman test showed a significant difference among the BIS baseline values, the values during pressure application on the extra 1 point for 2.5, 5.0, 7.5, and 10 min, and the values after pressure release (P < 0.001). The BIS values obtained before, 2.5 min, and 5.0 min during the pressure application on the control point also differed (P < 0.001). Individual comparisons showed a significant decrease in the BIS values during pressure application of the extra 1 point at all time points when compared with the baseline values (P < 0.001 for all individual comparisons). BIS values during pressure application were also lower when compared with the BIS value obtained after pressure release (P < 0.001) (Table 1). Pressure application on the control point also reduced the BIS values after 2.5 and 5.0 min (P < 0.001 and P < 0.001, respectively). The baseline BIS values recorded for the extra 1 and control point were similar but significantly lower for the extra 1 point during the 2.5- and 5.0-min period of pressure application (P < 0.001 and P < 0.001, respectively) (Table 1). This difference between the extra 1 and control points was 0% before pressure application and 44% and 109% 2.5 and 5.0 min after pressure application, respectively. Figure 3 shows the BIS ± sd values recorded for each time point during and after pressure application on the extra 1 and control points.

Table 1
Table 1:
Cumulated Bispectral Index (BIS) Values Before Applying Pressure on the “extra 1” Point, 2.5, 5, 7.5, and 10.0 min During Pressure Application and 3 min After Pressure Release; in the Control Point, Pressure was Applied only for 5 min
Figure 3
Figure 3:
Mean (sd) values of bispectral index (BIS) before, every 30 s during pressure application on the extra 1 point and on the control point, and after pressure release on the extra 1 point.

The VSS values were reduced by 50% after pressure application on the extra 1 point (P < 0.001) and by 14% after pressure application on the control point (P < 0.001). The VSS values were similar in both the extra 1 point and control point before applying pressure but differed after pressure application (P < 0.001) (Fig. 4).

Figure 4
Figure 4:
Verbal sedation score (VSS) values (mean ± sd) before and after pressure application on the extra 1 point and on the control point. * versus #, P = 0.001 for the VSS values before and after pressure application on the extra 1 point. ** versus ##, P = 0.001 for the VSS values before and after pressure application on the control point. * versus **, P = 0.921 for the VSS values before pressure application on the extra 1 and the control point. # versus ##, P < 0.05 for the VSS values after pressure application on the extra 1 point and the control point.

Discussion

Our results demonstrate a 50% reduction in BIS values when pressure was applied on the extra 1 point and a 50% reduction in anxiety and stress by pressing this point for 10 minutes. These findings, although difficult to interpret, may prove to be important in controlling preoperative fear and stress, particularly in the ambulatory setting.

Sedatives and opioids, often used as a premedicant, are associated with drowsiness, respiratory depression, and hangover after surgery, all of which are undesirable effects, particularly for the ambulatory patient (2,3). Benzodiazepines, the most common premedicant administered to alleviate preoperative anxiety and stress, may interact with the hypnotics and analgesics and prolong patient discharge. In addition, opioids cause or contribute to postoperative nausea and vomiting. Nonpharmacological techniques to prevent or treat pain and emesis during surgery will not prolong sedation after surgery or increase the incidence of vomiting of these patients and are cost-effective (5).

Several reports evaluate the application of acupuncture to treat acute and chronic pain (8–10,15). Kotani et al. (15) have shown that preoperative acupuncture decreased incisional and visceral pain after surgery. It also reduced the incidence of nausea and vomiting, the requirements of IV morphine, and attenuated the sympathetic response to surgery by reducing the postoperative levels of cortisol and epinephrine by 30%–50%(15). In a double-blinded, randomized, controlled study, Greif et al. (16) showed that transcutaneous electrical stimulation of an acupuncture point in the ear significantly decreased desflurane concentrations required to prevent the response to a noxious electrical stimulation. These authors (16) reported a 10% nonresponse to the transcutaneous electrical stimulation of an auricular acupuncture point. The higher sd values of the BIS mean that we observed during acupressure on the extra 1 point suggest a variability of response among the volunteers.

Similarly, premedicants may be replaced by techniques of traditional Chinese medicine, relaxing the patient before surgery without contributing to postoperative drowsiness, hangover, or nausea and vomiting. However, reports and evaluation of nonpharmacological methods to relieve preoperative anxiety stress and fear are very limited. In a recent report, Wang et al. (11) have shown that patients undergoing elective ambulatory surgery experienced less preoperative anxiety when auricular acupuncture was used. In contrast to auricular acupuncture, acupressure applied to the extra 1 point offers several advantages: (a) it does not affect the integrity of epidermis, (b) it is not invasive, and (c) it is easily applicable by the subject, particularly if an appropriate device were to be manufactured, even in the absence of a physician or trained and licensed acupuncturist. In addition, the poor perfusion of the chondral tissue in the ear favors the development of infection, and this may be considered a disadvantage of auricular acupuncture.

Nonpharmacological techniques are not expected to interact and change the pharmacokinetics of the anesthetic drugs, are unlikely to prolong recovery, and do not depress respiration or the cardiovascular system. Their application is simple, easy to apply, and, in contrast to new anesthetics or sedatives, is not expensive. Application of pressure to the extra 1 point was associated with relaxation and with a pleasant feeling afterwards, which, according to the volunteers’ reports, lasted between one and three hours. In contrast, pressure application on the control point was associated with an unpleasant feeling. The volunteers did not tolerate pressure on the control point well. For this reason, BIS value recording was limited to five minutes. This difference in treatment duration between the extra 1 and control points may be a flaw of the study. Nevertheless, after applying pressure for five minutes, BIS values were already decreased by more than 50% in the extra 1 but not in the control point.

The extra 1 point lies between the eyebrows on the midline at the root of the nose. These extra points are not located on any of the 14 meridians. In 1984, the World Health Organization established an international standard for acupuncture point names including the 31 most common acupuncture extra points (12). Acupressure is easy to apply to this extra point before surgery using a specialized elastic head strap, which is manufactured to fit to patients’ heads. The strap has some sort of button for pressing the area corresponding to the extra 1 point. Finally, the patient, if cooperative, can be instructed to self-apply pressure before arriving to the operating room. The method may prove to be effective in attenuating anxiety and stress in everyday life as well and may replace tranquilizers and hypnotics, at least in part, for thousands of people under stress.

The mechanism by which acupressure of the extra 1 acupuncture point produces relaxation is unknown. It may activate certain neural pathways or circuits, thus producing secretion of endogenous neurotransmitters. However, sophisticated and elegant studies dealing with basic research need to be performed to prove our hypothesis.

In conclusion, application of pressure on the extra 1 point in volunteers provided a significant decrease in BIS values and in the stress state. Preoperative stress may not be comparable to the stress experienced daily, and further studies are required to establish its value before surgery.

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