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Departments of
*Anesthesia,
Oral and Maxillofacial Surgery,
Preventive Medicine, and
§Psychology, The University of Iowa, Iowa City, Iowa
Address correspondence and reprint requests to M. M. Ghoneim, MD, The University of Iowa Hospitals and Clinics, The Department of Anesthesia, 200 Hawkins Dr., 6 JCP, Iowa City, IA 52242.
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Abstract |
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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.
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Introduction |
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Methods |
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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 body’s 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 Spielberger’s 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 surgeon’s 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
A research assistant obtained demographic data and administered a medical history form and a form that inquired about the patient’s use of tobacco, alcohol, marijuana, psychedelic drugs, and any other drugs. The patients completed the STAI and the nausea and pain VAS. Patients in Group E were given the hypnosis tape and were instructed to listen to it every day for 1 wk before surgery, including the morning of surgery. Group C was not given any tape.
Surgery Session
In the immediate preoperative period, measures of anxiety, nausea, and pain were recorded as in the previous session. Sedation, local anesthesia, and surgery were performed by the same surgeon in all cases. Sedation was standardized by the administration of fentanyl, 100 µg, midazolam, 0.1 mg/kg, and 50% nitrous oxide in oxygen via a nasal mask. Local anesthesia was accomplished with injections of lidocaine 2% with epinephrine 1:100,000, 1.8 mL per surgical quadrant. Standard monitoring was used. The surgeon assessed the difficulty of the operation by marking a VAS score. In the immediate postoperative period, measures of anxiety, nausea, and pain were again recorded. The prescribed analgesic medications were Vicodin ES, a mixture of hydrocodone 7.5 mg and acetaminophen 750 mg, one tablet every 4 to 6 h as needed for pain during the day of surgery and the first 3 postoperative days and ibuprofen 200 mg, one to two tablets every 4 to 6 h as needed for pain after the third postoperative day. If the pain was severe during the first three postoperative days and if the patients needed more relief, they were allowed to take ibuprofen with Vicodin.
Remaining Day of Surgery and the First Three Postoperative Days
Measures of anxiety, nausea, pain, the number of analgesic tablets which were consumed, and number of vomiting episodes were recorded each day. The STAI scale was completed once per day, and the VAS was completed four times per day.
1 Wk Postoperative Session
The surgeon recorded whether there had been complications related to the surgery and counted the number of remaining analgesic tablets.
The baseline characteristics of the two groups of patients were compared by using Fisher’s 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 surgeon’s 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 Fisher’s 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 Fisher’s exact test.
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Results |
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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.
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Discussion |
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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 surgery—sensations 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 (16–18).
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.
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Acknowledgments |
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This article has been cited by other articles:
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  G. H. Montgomery, D. David, G. Winkel, J. H. Silverstein, and D. H. Bovbjerg The Effectiveness of Adjunctive Hypnosis with Surgical Patients: A Meta-Analysis Anesth. Analg., June 1, 2002; 94(6): 1639 - 1645. [Abstract] [Full Text] [PDF]
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