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As medical costs continue to escalate, there is willingness to consider the role played by nontraditional factors in health. We investigated the usefulness of tape-recorded hypnosis instruction on perioperative outcome in surgical patients in a prospective, randomized, and partially blinded study. Sixty patients scheduled for third molar surgery were studied. Patients were allocated to either an experimental group (E) or a control group (C). Group E received an audio tape to listen to daily for the immediate preoperative week, which guided the patients through a hypnotic induction and included suggestions on enhancement of perioperative well-being. Group C did not receive any tapes. The same surgeon administered local anesthesia and a standard regimen of sedation and performed the operation for all patients. The following variables were assessed 1 wk before surgery, immediately before and after surgery, and for 3 days after surgery by the indicated measurements: State anxiety by a Spielberger scale; nausea and pain by visual analog scales; number of tablets of the analgesics that were used; number of episodes of vomiting; and complications. In addition, the surgeons assessment of ease of surgery was recorded. Two variables showed differences between the groups. First, Group C exhibited a mean increase of 11.7 points on the Spielberger scale from the screening to the presurgery period, while Group E showed only a mean increase of 5.5 points during the same period, P = 0.01. Second, the mean number of vomiting episodes was more in Group E, 1.3, than in Group C, 0.3, P = 0.02. In conclusion, anxiety was reduced before surgery by means of an audio tape containing hypnotic instructions; however, for no apparent reason, there was also an increase in the incidence of vomiting. Implications: We administered hypnosis instructions to patients before third molar surgery. Anxiety was reduced, but there was an increase in the incidence of vomiting. Although an easy and cost-effective method, the value of this approach remains to be established.
There is current interest in mind-body medicine and techniques, such as self-hypnosis, relaxation, and meditation (1). However, physicians are skeptical about the value of such therapies. There have been very few controlled studies investigating the effects of hypnosis in influencing the effects and outcomes of surgery, and most of these have been case reports (2). In a busy hospital setting, it is not practical to induce hypnosis separately for each individual patient. We, therefore, elected to induce preoperative self-hypnosis by using an audio tape. We tested its usefulness in patients who underwent surgical removal of their third molarsan operation which has been used as a model to evaluate the effects of therapeutic interventions on anxiety, pain, edema, inflammation, and other outcomes related to healing and recovery (3).
In a protocol approved by our ethics committee, 60 patients scheduled for surgical removal of their molar teeth were studied. After we obtained their written, informed consent, patients were allocated randomly to either an experimental (E) or control (C) group. There were 24 patients in Group E and 22 in Group C having four teeth extracted, five patients in Group E and six in Group C having three teeth extracted, and one patient in Group E and two in Group C having two mandibular teeth extracted. Thus, there were 30 patients in Group E and 30 in Group C. Patients were only invited to participate if they were between 18 and 35 yr of age; ASA physical status I or II; and without neurological or psychiatric disease, current or history of drug abuse, or current use of central nervous system active medications. Group E received a specially prepared audio tape, which had the following contents: a hypnotic relaxation-induction in which patients were guided to mental and physical relaxation; suggestions to find a tranquil state; suggestions to enhance the bodys mechanisms for control of bleeding and healing; and instructions on how direct suggestions can alleviate pain and enhance well-being. The tape was an English translation and adaptation of a tape which had been used before by Enqvist and Fisher (3) and Enqvist et al. (4,5). It was recorded by an experienced hypnotist. Anxiety was assessed by using the Spielbergers State-Trait Anxiety Inventory (STAI) (6). The STAI is the most widely used self-assessment instrument for measuring anxiety. The state scale assesses situation-related anxiety and is recommended for measuring preoperative anxiety (7). Nausea and pain were measured by using visual analog scales (VAS) scored by the patient on 100-mm horizontal lines anchored by the verbal descriptors "no nausea," "very nauseous," "no pain," and "worst pain imaginable". The surgeons assessment of ease of surgery was scored by the surgeon on a VAS, anchored by the descriptors "easy" and "most difficult." The distances in mm from the low anchor ends of the scales were used. Higher scores on the VAS and the STAI represented worst conditions. Blood pressure and heart rate were measured. The number of tablets of analgesics which were used by the patients were reported by them and were confirmed by a pill count at the end of the study. The incidence of vomiting was reported by the patients, and complications were reported by the surgeon.
Screening and Baseline Measurements Session
Surgery Session
Remaining Day of Surgery and the First Three Postoperative Days
1 Wk Postoperative Session The baseline characteristics of the two groups of patients were compared by using Fishers exact test, the two-sample t-test, or the Wilcoxon-Mann-Whitney statistic, as appropriate. The mean changes from screening to preoperative sessions and from preoperative to postoperative sessions, in vital signs and anxiety ratings in the two groups were compared by using the two-sample t-test. Two-sample tests were also used to compared the groups with respect to the surgeons assessment of difficulty, surgery duration, STAI, nausea, and pain scores, analgesic use, and vomiting. Because the assumptions of the two-sample t-test were not always satisfied, these analyses were repeated using the Wilcoxon-Mann-Whitney nonparametric tests. The results of the parametric and nonparametric tests were always similar. Because most patients reported no nausea (at all of the assessments) and no pain (at the preoperative and immediate postoperative assessments), these data were analyzed both as categorical variables (none versus some) and as quantitative variables. Both Fishers exact tests and Wilcoxon-Mann-Whitney statistics were used. This same approach was also used in the analysis of the analgesic use and vomiting scores. Complication rates in the two groups were compared by using Fishers exact test.
All the patients in the Group E reported listening to the tape daily during the week preceding surgery. We combined the results of the few patients who had extraction of their mandibular third molars only with those who had extraction of three teeth because most of the pain after surgery came from the mandibular sites. There were no differences in demographic characteristics and baseline values between the Groups E and C that even approached statistical significance (Table 1). Comparison of the two groups with respect to the mean change from the screening to the immediate preoperative sessions showed that on the STAI, the patients in Group C scored a mean (SD) increase of 11.7 (7.2) points, whereas those in Group E exhibited a smaller mean increase of 5.5 (13.9) points. Based on a two-sided two-sample unequal variance t-test, the means differed significantly (P = 0.03). Because the assumptions of the t-test may not be reasonable, the two groups were also compared by using the Wilcoxon-Mann-Whitney U-test. Again, the difference was significant (P = 0.01). There were no differences between the two groups concerning changes of other variables by using either test. None of the changes from the immediate preoperative to the immediate postoperative periods was significant.
The surgeon marked a VAS for the difficulty with the surgical procedure for each extracted tooth. Because not all patients had all four assessments, we derived two variables, maximal VAS and average VAS scores. These were 45.7 (22.1) and 35.8 (22.9) for the maximal VAS score for Groups C and E, respectively; and 31.1 (17.8) and 36.3 (18.3) for the average VAS score for Groups C and E, respectively. The P values were 0.18 and 0.28. The mean duration of surgery was very similar in the two groups: 19.7 min in Group C and 20.3 min in Group E. There were no differences between the two groups of patients in their consumption of postoperative analgesics on the day of surgery and the first three postoperative days. However, the mean number of vomiting episodes was significantly more frequent in Group E than in Group C (Table 2). The number of complications was equal in the two groups. Three patients in Group E suffered from a "dry socket" (lack of blood clot in the alveolus), compared with two patients in Group C with a dry socket and one patient who developed a subperiosteal infection, which required incision and drainage, and a course of antibiotics. In all cases, the results of the categorical analysis (none versus some) were similar to the quantitative analysis.
This study shows that listening to an audio tape containing hypnotic instructions for one week before molar teeth extractions results in reduced anxiety before surgery. This finding is consistent with results from other clinical studies in which preoperative anxiety was treated with hypnosis, induced either through an audio tape or a therapist (3,4,8,9). Psychological stress is often present in the preoperative period (10), and it is prudent to relieve it. Patients with a high anxiety level seem to have a greater surgical risk than those with low anxiety, and there may be a correlation between preoperative anxiety and the rate of postoperative recovery (11). Pharmacological preparation of the patient is often effective, but it may cause undesirable side effects. We also observed an increase in the incidence of vomiting in Group E. This was unexpected and, despite the multifactorial cause of postoperative nausea and vomiting (12), we could not identify a difference between the two groups, which could account for this finding. Enqvist et al. (5), using a tape similar to the one that we used, found that it reduced postoperative vomiting after breast surgery. Faymonville et al. (2) also found that hypnosis reduced the incidence of nausea and vomiting in patients who underwent plastic surgery under local anesthesia and IV sedation. The suggestions in the tape emphasized that patients would feel hunger, thirst, and a desire to drink and eat after surgerysensations incompatible with vomiting. A patient who is calm before surgery usually has higher levels of plasma cortisol (13), which have been associated with reduced nausea and vomiting (14). We found no improvement in the severity of postoperative pain as assessed by the VAS and the consumption of analgesics. Enqvist and Fischer (3), using a similar tape and protocol in patients undergoing extraction of mandibular third molars, found that hypnosis reduced the consumption of analgesics by the patients. Preemptive analgesia induced by hypnosis has also been found in other studies (2,3,15). Hypnosis has also been effective in alleviating pain associated with cancer, as well as other chronic pain conditions (1618). Our Group C received no pretreatment. It would have been ideal to look for and quantify any placebo effect. Unfortunately, it would be very difficult to convince patients to listen to a tape of white noise daily for a week and to assure their compliance. We did consider using a relaxation tape in the control group during the planning stage of this study, but decided to leave this approach for a future study, which would distinguish between a hypnotic approach and a pure relaxation approach for affecting perioperative outcomes. We did not assess personality factors, such as the hypnotic susceptibility of the patients. Subjects vary in their hypnotic susceptibility and suggestibility for reasons which are not adequately understood. We assumed, as do many eminent researchers in the field (19), that all patients are responsive to hypnosis if properly approached. The therapist-patient relationship, not hypnotizability, has been shown to predict treatment outcome. However, establishment of mutual confidence between the therapist and the patient and the personal clarification of the goals and limitations of the therapy, which seem to be essential in order to maximize patient responsiveness to suggestions, were absent in this study. Enqvist and Fisher (3) and Enqvist et al. (4,5) used a similar self-hypnosis tape without assessment of hypnotic susceptibility and with much more successful outcomes (e.g., reduced anxiety, nausea, vomiting, and need for postoperative analgesics) than ours. An experienced and enthusiastic clinical hypnotist and psychotherapist, Enqvist introduced the methods personally to each patient and was available for each patient over the course of the study. Such personal advocacy was lacking in our study. The only introduction to the patient in our study was a statement that "listening to the tape containing positive suggestions may reduce anxiety about surgery, decrease the degree of pain following surgery, and lessen the incidence of nausea and vomiting" in the information summary given to the patients before they gave their consent. It is possible that with such a neutral approach, hypnotizability is more important for the success of treatment, and patients may vary in the degree to which they benefit from preoperative hypnosis reflecting their hypnotizability differences. This area needs to be explored in the future to maximize the benefits of therapy. Another limitation of the study is the absence of information about the state of the patients while they were listening to the tape. We do not know whether hypnosis actually occurred in every patient. Without an observer experienced in recognizing a hypnotic state or some measure of depth of trance, this would be difficult to ascertain. Asking the patients to rate the depth of relaxation they attained after each session and the usefulness and credibility of the treatments at the end of the study would have also provided some useful information. These areas should be explored in future studies. In summary, our data show tape-recorded hypnosis instruction, an easy and cost-effective method, can reduce preoperative anxiety. However, there was also an increase in the incidence of postoperative vomiting. Therefore, the value of the tape-recorded hypnosis instructions as administered in this study is questionable.
We thank Dr. B. Enqvist for kindly supplying the self-hypnosis tape and for his interest in the subject.
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