British Journal of Anaesthesia 1992; 68: 277-281
THERAPEUTIC SUGGESTIONS DURING GENERAL ANAESTHESIA IN PATIENTS UNDERGOING HYSTERECTOMY W. H. D. LIU, P. J. STANDEN AND A. R. AITKENHEAD SUMMARY
KEY WORDS Anaesthesia, general, /earning, memory. Complications: awareness, memory.
Several reports have suggested that postoperative behaviour of patients may be altered [1,2] and that patients may perform better on tests of implicit memory in the postoperative period [3-5] in response to auditory material presented during general anaesthesia. Such reports have led to the suggestion that information may be registered, processed, or both, in some areas of the anaesthetized brain [6, 7]. In addition, it has been suggested that positive therapeutic suggestions presented during operation may lead to fewer postoperative complications in patients undergoing hysterectomy [8] or cholecystectomy [9], resulting in significant reduction in postoperative morbidity and shorter duration of hospital stay. However, the initial demonstration [9] of improved postoperative outcome after cholecystectomy was not confirmed when the same group of investigators repeated the study [10]. Consequently, it is not clear if therapeutic suggestions during general anaesthesia improve postoperative outcome. Furthermore, even if outcome is influenced by presentation of auditory material during anaesthesia, it is not clear if such improvements may be attributed to the content of the messages, or to the presence of a reassuring voice during surgery. Therefore, the aims of this study were two-fold: first, to investigate if the previous report of improved postoperative outcome in relation to positive intraoperative suggestions after hysterectomy [8] was reproducible; and second, to establish the relationship between postoperative progress and the content of messages presented during general anaesthesia.
In a double-blind, controlled investigation, we studied 75 healthy (ASA I or II) patients undergoing total abdominal hysterectomy at the University Hospital, Queen's Medical Centre, Nottingham. The patients were allocated randomly to one of three groups according to the content of the tapes (see below) presented during anaesthesia. Patients were excluded if they had impairment of hearing or a history of psychiatric illness. The study was approved by the Hospital Ethics Committee. All patients were visited one day before operation and written informed consent obtained. The mood state and anxiety level of the patient were assessed by a short form of the profile of mood states questionnaire [11] and the Spielberger state-trait anxiety inventory [12], respectively. The contents of the tapes comprised a 15-s blank at the beginning of each tape (used subsequently to record the preferred name of the patient), followed immediately by the phrase " Listen to me carefully ", to avoid revealing the contents of the tape inadvertently to the investigators. Finally, the tape contained one of three recordings: therapeutic suggestions, which were identical to the suggestions used in a previous study [8], and consisted of both affirmative suggestions (for instance, "after the operation, you will have a comfortable and rapid recovery... and so on); non-affirmative suggestions (for instance, you will have no pain...you will not feel sick...) and contained neither encouraging words (such as "excellent" or "best") nor encouraging sentences such as the ones above; and a blank recording with no message. The same speaker was used on both tapes which contained a message. Each message lasted for 10 min. All the tapes were prepared in a recording studio by an experienced technician from the Behavioural Sciences section of the Department of Psychiatry. All recordings, including that on a test tape, were adjusted carefully to produce comparable volume output. The volume output from the portable cassette player was adjusted to suit individual patients so that the test message was heard clearly and correctly. There were five
W. H. D. Liu, M.B., B.CH., F.C.ANAES., A. R. AITKENHEAD, B.SC.,
M.D., F.C.ANAES. (University Department of Anaesthesia); P. J. STANDEN, PH.D. (Behavioural Science Section, Department of Psychiatry); University Hospital, Queen's Medical Centre, Nottingham NG7 2UH. Accepted for Publication: September 9, 1991.
Downloaded from http://bja.oxfordjournals.org/ at University of California, San Diego on August 19, 2015
In a double-blind, randomized study, we have examined the influence of positive therapeutic suggestions, presented to anaesthetized patients undergoing total abdominal hysterectomy, on postoperative morbidity and duration of hospital stay. Seventy-five patients were allocated randomly to be exposed to one of three tapes containing positive therapeutic suggestions, a modified history of the Queen's Medical Centre, or no message. We found that neither therapeutic suggestions nor the presence of a voice during anaesthesia improved postoperative outcome or reduced duration of hospital stay after total abdominal hysterectomy.
PATIENTS AND METHODS
BRITISH JOURNAL OF ANAESTHESIA
278
TABL£ I. Mean (range or SD) of potential confounding variables bettoeen all three groups of patients. * Median scores. No significant differences among groups. SR = Senior Registrar; Reg. = Registrar; SHO = Senior House Officer
Group H (n = 25)
Group B (n = 24)
42.1 (22-64) 70.7 (13.8) 12.7(1.5)
43.3 (34-65) 69.4(15.1) 13.5(1.2)
43.5 (32-59) 63.4 (13.0) 13.0(1.2)
71.0
73.0
70.0
48.1 (13.6) 81.4(16.2)
43.5 (12.0) 71.2(23.6)
46.2(12.7) 75.6 (14.3)
416.8 (48.7) 7.0(1.6)
536.0 (103.0) 6.4 (2.0)
497.3(61.5) 6.8(1.6)
17 7
tapes of each type and therefore 15 tapes, of identical appearance. Groups of fifteen patients were allocated randomly to receive one of these coded tapes. At the end of the recruitment of 15 patients, the codes on the tapes were revealed by another anaesthetist not directly involved in any other part of the study, so that the double-blindness of the tapes was maintained. The whole process was repeated until 75 patients (five groups of 15 patients) were recruited. All patients were premedicated with papaveretum 0.15 mg kg"1 and prochlorperazine 0.18 mg kg"1 i.m. before operation. They were anaesthetized using a standard anaesthetic technique which consisted of thiopentone 5 mg kg"1 and vecuronium 0.1 mg kg"1. Their lungs were ventilated with 66 % nitrous oxide and 1-1.5% enflurane in oxygen. Analgesia was supplemented with papaveretum 0.1 mg kg"1 if necessary. The earpieces of the tape-recorder were positioned carefully and secured with adhesive tape in the anaesthetic room. A pair of adjustable and well fitted industrial sound protectors was placed over the patient's ears to reduce perception of operating theatre sounds to a minimum. The tapes were started precisely at the time of the first skin incision and played continuously throughout surgery until the beginning of wound closure. At the end of the operation, administration of enflurane was discontinued, and residual neuromuscular block antagonized with neostigmine 0.035 mg kg"1 and glycopyrronium 0.008 mg kg" 1 .-The duration of operation, volume of blood loss, the number of times the tape was played and the grade of the surgeon were recorded. All patients were followed up daily by one investigator. On the first day after operation, the patients were asked if they had any recall of events or dreams during operation. They were asked to guess which tape they had heard and to guess the total number of hospital beds at the Queen's Medical Centre by choosing the correct number from the following four choices: 1100, 1200, 1300 and 1400 beds. The correct number (1200 beds) was mentioned on the "history of hospital" tape. Pain was assessed every 2 h for 12 h on the first day after operation using visual analogue scales. Relief of pain was provided by intermittent i.m. injections of
17 8
17 7
papaveretum on demand for the first 48 h, and oral coproxamol thereafter. The quantity of each type of analgesic administered was recorded for the duration of hospital stay. Nausea and flatulence were assessed once daily on the first 2 days after the operation. Pyrexia was recorded as the number of 12-h periods in which a temperature greater than 37.3 °C was recorded. The ease of mobility was assessed daily for the first 3 days after operation using a five-point mobilization scale, and a cumulative score was recorded. On the 5th day after operation, the mood state and anxiety level were re-assessed using the same psychological tests used before the operation. Any complications such as chest infection, urinary tract infection or wound infection were recorded. The duration of hospital stay was recorded to the nearest half-day: if the patient was discharged before mid-day, it was counted as a half-day stay and after mid-day the stay would be 1 day. Before discharge, the nursing staff were asked to grade the overall recovery of the patient as "as expected", or better or worse than expected. None of the nurses knew which tape the patient had heard during operation. Parametric data were analysed by analysis of variance and non-parametric data were analysed with Kruskal-Wallis and chi-square tests. P < 0.05 was considered significant. RESULTS
No patient refused the invitation to participate. Two patients were excluded from statistical analysis; one (suggestion group) required further surgery during her stay in hospital and the other patient's operation was cancelled. Consequently, there were 24 patients in the suggestion group (group S), 25 in the history group (group H) and 24 in the blank tape group (group B). There were no significant differences among the three groups in age, weight, preoperative haemoglobin concentration, preoperative mood state or anxiety level, estimated blood loss, duration of operation or the number of times the tape was played (table I). None of the patients had any recall of intraoperative events or dreams. One patient had two episodes of nightmares about her operation and
Downloaded from http://bja.oxfordjournals.org/ at University of California, San Diego on August 19, 2015
Age (yr) t Weight (kg) Haemoglobin concn (gdl- 1 ) Profile of mood states, before op.* Anxiety scores Duration of operation (min) Blood loss (ml) Message played (No. of times) Grade of surgeons Consultants SR/Reg/SHO
Group S (n = 24)
279
THERAPEUTIC SUGGESTIONS DURING ANAESTHESIA
TABLE III. Patients' guesses on messages received and the number of hospital beds, and the nursing assessment of postoperative recovery. No significant difference was found between groups
T ;-.
I
i Ol
patients
20
i
i
° 106 2
500.0
-i
2.0
4.0 6.0 8.0 10.0 Duration of hospital stay (days)
12.0
F I G . 1. Pattern of hospital discharge of patients in suggestion group ( ), history group ( - • • - ) and blank tape group ( • • • • ) •
thought she had listened to the suggestion tape; in fact, she had listened to the tape containing the history of the hospital. There were no differences between groups in the pattern of discharge for all patients (fig. 1). There were no significant differences between the three groups in respect of pyrexia, pain scores, analgesic requirement, nausea, flatulence, mobility, wound or other complications (tables II, III). The patient's guesses of the tape played during operation were not influenced by the tape which had been used. There was no association between the tape heard and patients' estimate of the number of beds in the Queen's Medical Centre. There were no differences in the nurses' assessment of the overall recovery of the patients. DISCUSSION
Neither spontaneous nor prompted recall is of sufficient sensitivity to assess if information presented during anaesthesia adequate for surgical operation is processed, registered, or both, in the anaesthetized brain [1]. Therefore more sophisticated methods such as implicit memory tests [3-5, 13], non-verbal responses [1, 2], hypnosis [14] and improvement in postoperative outcome [8, 9, 15] have been used to provide indirect evidence of information registration during anaesthesia. In earlier studies, reduction in the incidence of postoperative complications and duration of hospital stay were reported in patients who were presented with positive suggestions during anaesthesia [15—17].
Group H (n = 25)
Group B (n = 24)
8 2 14
11 5 9
9 3 12
12 4 8
15 6 4
14 5 5
7 17
9 16
9 15
These findings were supported by the results of studies with better design which involved patients undergoing only one type of operation [8, 9]. Bonke and colleagues suggested that, after cholecystectomy, only patients aged 55 yr or older demonstrated significant improvements; they attributed this to the fact that older patients were more likely to develop secondary complications in the postoperative period [9]. However, when this study was repeated subsequently by the same group of investigators using more control groups, the initial encouraging results were not confirmed [10], despite the use of identical therapeutic suggestions [9]. In another study, improvement in postoperative outcome was also not evident in patients who received therapeutic messages suggesting a rapid recovery, although the number of patients studied was relatively small [18]. More recently, patients who were given therapeutic suggestions during anaesthesia were reported to have significant reduction in requirement for postoperative analgesia, as assessed using a patient-controlled device to provide more objective measure of analgesic requirements [19]. However, the extent of reduction in analgesic requirements was small. In summary, evidence for the ability of intraoperative suggestions to improve postoperative outcome has been conflicting. Evans and Richardson reported that therapeutic suggestions during anaesthesia reduced duration of
TABLE II. Mean (SD) or median (quar tiles) of recovery variables. No significant difference was found between groups
Duration of hospital stay (days) Pyrexia (half-days) Pain intensity (0-100) I.m. analgesia (mg) Oral analgesia (mg) Profile of mood states, after op. Nausea (0-100) Flatulence (0-100) Mobilization (0-15) Wound (0-^1)
Group S (« = 24)
Group H (" = 25)
Group B (n = 24)
6.9(1.3)
6.9(1.6)
6.6(1.1)
5.2 (3.4) 39.7 (20.6) 94.0 (32.5) 23.8(15.6) 69.0
4.4 (2.8) 35.9(14.5) 77.2 (29.2) 20.6(11.8) 70.0
3.8 (2.2) 30.0(17.7) 85.7 (32.9) 18.7(10.8) 68.0
23.7(31.8) 32.7(27.1) 7.6(1.6) 0.7(1.2)
16.3(21.6) 42.6 (28.9) 7.8(1.2) 0.4 (0.8)
22.1 (19.8) 24.8(21.9) 7.8(1.3) 0.4 (0.9)
Downloaded from http://bja.oxfordjournals.org/ at University of California, San Diego on August 19, 2015
Patient guess of tape content Suggestion tape History tape Blank tape Nurses' assessment of recovery As expected Better than expected Worse than expected Patient guess of no. of hospital beds Correct Incorrect
i
Group S (n = 24)
280
however, patients in this study who were exposed to the "history of hospital" tape did not perform significantly better than those in the other two groups. Goldman reported significantly better performance in patients who were given answers to specific questions during anaesthesia [25]. However, there are two major differences between Goldman's study and our own: first, the message used in Goldman's study was relatively brief compared with the complicated history of the Queen's Medical Centre; and second, the patients in the present study were not given warning before the operation of the unlikely postoperative question regarding the number of hospital beds. This may suggest that, in order to examine information registered during anaesthesia, the information should be specific and brief, and that the patients should be primed to the type of information they are likely to receive during their operation. Although there is some evidence from previous studies that limited processing of information might occur during anaesthesia, the influence of positive therapeutic suggestions on postoperative outcome is questionable [10, 18]. This may be partly because of the complexity of factors which influence outcome; partly because the variables selected to assess outcome may not be sensitive to differences attributable to therapeutic suggestions; and, finally, because of inter-patient or inter-study variability, or both, in the depth of anaesthesia in various studies. Although it has been suggested that patients should be exposed to positive suggestions routinely during operation in the hope of improving postoperative outcome [7, 8, 21, 22], it is imperative to show that such improvements are readily reproducible. The results of the present study suggest that, in otherwise healthy patients undergoing total abdominal hysterectomy using our anaesthetic technique, there was no evidence of any improvement in postoperative outcome related to either positive therapeutic suggestions or the presence of a voice during anaesthesia. However, this conclusion must be qualified by the fact that the number of patients in this study was very small and it is not possible to exclude the possibility that our findings would be reproduced in a larger study. ACKNOWLEDGEMENT This study was supported financially by a grant from the BUPA MedicaJ Foundation Ltd. REFERENCES 1. Bennett HL, Davis HS, Giannini JA. Non-verbal response to intraoperative conversation. British Journal of Anaesthesia 1985; 57: 174-179. 2. Goldman L, Shah M, Hebden M. Memory of cardiac anaesthesia: Psychological sequelae in cardiac patients of intra-operative suggestions and operating room conversation. Anaesthesia 1987; 42: 596-603. 3. Millar K, Watkinson N. Recognition of words presented during general anaesthesia. Ergonomics 1983; 26: 585-594. 4. Stolzy S, Couture LJ, Edmonds HL jr. Evidence of partial recall during general anesthesia. Anesthesia and Analgesia 1986; 65: S154. 5. Block RI, Ghoneim MM, Sum Ping ST, Ali MA. Human learning during general anaesthesia and surgery. British Journal of Anaesthesia 1991; 66: 170-178.
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hospital stay and postoperative morbidity significantly in patients who had undergone total abdominal hysterectomy [8]. We have been unable to reproduce this result in our study, despite the use of identical therapeutic suggestions in the two studies. Furthermore, Evans and Richardson also reported very accurate guesses by the patients in respect of the tape to which they were exposed to during anaesthesia; all but one patient (18 of 19) in the suggestion group guessed correctly that they had been exposed to intraoperative suggestions. In addition, the pattern of assessments by nursing staff of the overall recovery of the patients matched almost exactly the correct guesses of the patients. These results also were not reproduced in the present study. In the context of preconscious processing of information presented to the anaesthetized brain, it has been suggested that general anaesthesia may cause dissociation between explicit (which requires conscious effort to recall events) and implicit (which does not require any effort) memory [20]. The incidence of implicit memory of information presented or of other intraoperative events during anaesthesia is not known precisely, but it-is likely to be much greater than the incidence of explicit memory [21,22]. Nevertheless, registration of information under anaesthesia is considered to be very fragile, so that, even when sensitive implicit memory tests are applied, the evidence is not robust [5, 23]. Consequently, the high degree of accuracy in patients' guesses and nurses' assessment of the use of the suggestion tape in Evans and Richardson's study was unexpected; indeed, doubts on the double-blind nature of their study have been expressed [24]. However, it is possible that the difference between the two studies can be attributed to differences in depth of anaesthesia either throughout the operation or towards the end of the procedure when volatile agents might have been discontinued before the end of surgery but while the tapes were still being played. A standard anaesthetic technique was not used in Evans and Richardson's study, in that a large variety of different anaesthetic drugs was administered by several anaesthetists. This may have increased the variability in the depth of anaesthesia in different patients, therefore increasing the likelihood of information registration in those who were exposed to suggestion tape in their study. The use of duration of stay as a means of postoperative recovery is open to criticism, in that it may be influenced by many factors, including differences in normal practice among consultant surgeons. In the present study, patients were admitted under the care of one of three surgeons. The distribution of consultant surgeons in each group was: group S—7,9,8; group H—8,8,9; group B—7,9,8. The median duration of stay, irrespective of group, was 6.5 days for patients of all surgical consultants. However, other factors may have influenced the decision to discharge patients from hospital. In addition, this is a very insensitive index of recovery from anaesthesia and surgery. In the present study, the estimation of the number of hospital beds was used as a form of memory test;
BRITISH JOURNAL OF ANAESTHESIA
THERAPEUTIC SUGGESTIONS DURING ANAESTHESIA 17. 18. 19.
20.
21. 22. 23.
24. 25.
a report and evaluation of 200 consecutive cases. American Journal of Clinical Hypnosis 1961; 4: 26-29. Wolfe LS, Millet JB. Control of post-operative pain by suggestion under general anesthesia. American Journal of Clinical Hypnosis 1960; 3: 109-112. Woo R, Seltzer JL, Marr A. The lack of response to suggestion under controlled surgical anesthesia. Acta Anaesthesiologica Scandinavica 1987; 31: 567-571. McLintock TTC, Aitken H, Downie CFA, Kenny GNC. Postoperative analgesic requirements in patients exposed to positive intraoperative suggestions. British Medical Journal 1990; 301: 788-790. Kihlstrom JF, Schacter DL. Anaesthesia, amnesia and the cognitive unconscious. In: Bonke B, Fitch W, Millar K, eds. Memory and Awareness in Anaesthesia. Amsterdam: Swets, 1989: 21-44. Jones JG, Konieczko K. Hearing and memory in anaesthetized patients. British Medical Journal 1986; 292: 12911293. Griffiths D, Jones JG. Editorial I. Awareness and memory in anaesthetized patients. British Journal of Anaesthesia 1990; 65: 603-606. Millar K. Memory during anaesthesia. In: Gruneberg MM, Morris PE, Sykes RN, eds. Practical Aspects of Memory : Current Research and Issues, Vol. II, Clinical and Educational Implications. New York: John Wiley, 1987. Mackie DS. Therapeutic suggestions during general anaesthesia. Lancet 1988; 2: 955-956. Goldman L. Awareness under general anaesthesia (Ph.D. dissertation). Cambridge: University of Cambridge, 1986.
Downloaded from http://bja.oxfordjournals.org/ at University of California, San Diego on August 19, 2015
6. Goldmann L. Information processing under general anaesthesia : a review. Journal of the Royal Society of Medicine 1988; 81: 224-227. 7. Editorial. Advertising during anaesthesia? Lancet 1986; 2: 1019-1020. 8. Evans C, Richardson PH. Improved recovery and reduced postoperative stay after therapeutic suggestions during general anaesthesia. Lancet 1988; 2: 491^193. 9. Bonke B, Schmitz PIM, Verhage F, Zwaveling A. Clinical study of so-called unconscious perception during general anaesthesia. British Journal of Anaesthesia 1986; 58: 957-964. 10. Boeke S, Bonke B, Bouwhuis-Hoogerwerf ML, Bovill JG, Zwaveling A. Effects of sounds presented during general anaesthesia on postoperative course. British Journal of Anaesthesia 1988; 60: 697-702. 11. McNair DM, Lorr M, Droppleman LF. Profile of Mood States Manual. San Diego: Educational and Industrial Testing Service, 1971. 12. Spielberger CD, Gorsuch RL, Lushene RE. State-Trait Anxiety Inventory Manual. California: Consulting Psychologists Press Inc., 1970. 13. Eich E, Reeves JL, Katz RL. Anesthesia, amnesia and the memory/awareness distinction. Anesthesia and Analgesia 1985; 64: 1143-1148. 14. Levinson BW. States of awareness during genera] anaesthesia. British Journal of Anaesthesia 1965; 37: 544-546. 15. Pearson RE. Response to suggestions given under general anesthesia. American Journal of Clinical Hypnosis 1961; 4: 106-114. 16. Hutchings D. The value of suggestion given under anesthesia:
281
THERAPEUTIC SUGGESTIONS DURING GENERAL ANAESTHESIA IN PATIENTS UNDERGOING HYSTERECTOMY W. H. D. LIU, P. J. STANDEN AND A. R. AITKENHEAD SUMMARY
KEY WORDS Anaesthesia, general, /earning, memory. Complications: awareness, memory.
Several reports have suggested that postoperative behaviour of patients may be altered [1,2] and that patients may perform better on tests of implicit memory in the postoperative period [3-5] in response to auditory material presented during general anaesthesia. Such reports have led to the suggestion that information may be registered, processed, or both, in some areas of the anaesthetized brain [6, 7]. In addition, it has been suggested that positive therapeutic suggestions presented during operation may lead to fewer postoperative complications in patients undergoing hysterectomy [8] or cholecystectomy [9], resulting in significant reduction in postoperative morbidity and shorter duration of hospital stay. However, the initial demonstration [9] of improved postoperative outcome after cholecystectomy was not confirmed when the same group of investigators repeated the study [10]. Consequently, it is not clear if therapeutic suggestions during general anaesthesia improve postoperative outcome. Furthermore, even if outcome is influenced by presentation of auditory material during anaesthesia, it is not clear if such improvements may be attributed to the content of the messages, or to the presence of a reassuring voice during surgery. Therefore, the aims of this study were two-fold: first, to investigate if the previous report of improved postoperative outcome in relation to positive intraoperative suggestions after hysterectomy [8] was reproducible; and second, to establish the relationship between postoperative progress and the content of messages presented during general anaesthesia.
In a double-blind, controlled investigation, we studied 75 healthy (ASA I or II) patients undergoing total abdominal hysterectomy at the University Hospital, Queen's Medical Centre, Nottingham. The patients were allocated randomly to one of three groups according to the content of the tapes (see below) presented during anaesthesia. Patients were excluded if they had impairment of hearing or a history of psychiatric illness. The study was approved by the Hospital Ethics Committee. All patients were visited one day before operation and written informed consent obtained. The mood state and anxiety level of the patient were assessed by a short form of the profile of mood states questionnaire [11] and the Spielberger state-trait anxiety inventory [12], respectively. The contents of the tapes comprised a 15-s blank at the beginning of each tape (used subsequently to record the preferred name of the patient), followed immediately by the phrase " Listen to me carefully ", to avoid revealing the contents of the tape inadvertently to the investigators. Finally, the tape contained one of three recordings: therapeutic suggestions, which were identical to the suggestions used in a previous study [8], and consisted of both affirmative suggestions (for instance, "after the operation, you will have a comfortable and rapid recovery... and so on); non-affirmative suggestions (for instance, you will have no pain...you will not feel sick...) and contained neither encouraging words (such as "excellent" or "best") nor encouraging sentences such as the ones above; and a blank recording with no message. The same speaker was used on both tapes which contained a message. Each message lasted for 10 min. All the tapes were prepared in a recording studio by an experienced technician from the Behavioural Sciences section of the Department of Psychiatry. All recordings, including that on a test tape, were adjusted carefully to produce comparable volume output. The volume output from the portable cassette player was adjusted to suit individual patients so that the test message was heard clearly and correctly. There were five
W. H. D. Liu, M.B., B.CH., F.C.ANAES., A. R. AITKENHEAD, B.SC.,
M.D., F.C.ANAES. (University Department of Anaesthesia); P. J. STANDEN, PH.D. (Behavioural Science Section, Department of Psychiatry); University Hospital, Queen's Medical Centre, Nottingham NG7 2UH. Accepted for Publication: September 9, 1991.
Downloaded from http://bja.oxfordjournals.org/ at University of California, San Diego on August 19, 2015
In a double-blind, randomized study, we have examined the influence of positive therapeutic suggestions, presented to anaesthetized patients undergoing total abdominal hysterectomy, on postoperative morbidity and duration of hospital stay. Seventy-five patients were allocated randomly to be exposed to one of three tapes containing positive therapeutic suggestions, a modified history of the Queen's Medical Centre, or no message. We found that neither therapeutic suggestions nor the presence of a voice during anaesthesia improved postoperative outcome or reduced duration of hospital stay after total abdominal hysterectomy.
PATIENTS AND METHODS
BRITISH JOURNAL OF ANAESTHESIA
278
TABL£ I. Mean (range or SD) of potential confounding variables bettoeen all three groups of patients. * Median scores. No significant differences among groups. SR = Senior Registrar; Reg. = Registrar; SHO = Senior House Officer
Group H (n = 25)
Group B (n = 24)
42.1 (22-64) 70.7 (13.8) 12.7(1.5)
43.3 (34-65) 69.4(15.1) 13.5(1.2)
43.5 (32-59) 63.4 (13.0) 13.0(1.2)
71.0
73.0
70.0
48.1 (13.6) 81.4(16.2)
43.5 (12.0) 71.2(23.6)
46.2(12.7) 75.6 (14.3)
416.8 (48.7) 7.0(1.6)
536.0 (103.0) 6.4 (2.0)
497.3(61.5) 6.8(1.6)
17 7
tapes of each type and therefore 15 tapes, of identical appearance. Groups of fifteen patients were allocated randomly to receive one of these coded tapes. At the end of the recruitment of 15 patients, the codes on the tapes were revealed by another anaesthetist not directly involved in any other part of the study, so that the double-blindness of the tapes was maintained. The whole process was repeated until 75 patients (five groups of 15 patients) were recruited. All patients were premedicated with papaveretum 0.15 mg kg"1 and prochlorperazine 0.18 mg kg"1 i.m. before operation. They were anaesthetized using a standard anaesthetic technique which consisted of thiopentone 5 mg kg"1 and vecuronium 0.1 mg kg"1. Their lungs were ventilated with 66 % nitrous oxide and 1-1.5% enflurane in oxygen. Analgesia was supplemented with papaveretum 0.1 mg kg"1 if necessary. The earpieces of the tape-recorder were positioned carefully and secured with adhesive tape in the anaesthetic room. A pair of adjustable and well fitted industrial sound protectors was placed over the patient's ears to reduce perception of operating theatre sounds to a minimum. The tapes were started precisely at the time of the first skin incision and played continuously throughout surgery until the beginning of wound closure. At the end of the operation, administration of enflurane was discontinued, and residual neuromuscular block antagonized with neostigmine 0.035 mg kg"1 and glycopyrronium 0.008 mg kg" 1 .-The duration of operation, volume of blood loss, the number of times the tape was played and the grade of the surgeon were recorded. All patients were followed up daily by one investigator. On the first day after operation, the patients were asked if they had any recall of events or dreams during operation. They were asked to guess which tape they had heard and to guess the total number of hospital beds at the Queen's Medical Centre by choosing the correct number from the following four choices: 1100, 1200, 1300 and 1400 beds. The correct number (1200 beds) was mentioned on the "history of hospital" tape. Pain was assessed every 2 h for 12 h on the first day after operation using visual analogue scales. Relief of pain was provided by intermittent i.m. injections of
17 8
17 7
papaveretum on demand for the first 48 h, and oral coproxamol thereafter. The quantity of each type of analgesic administered was recorded for the duration of hospital stay. Nausea and flatulence were assessed once daily on the first 2 days after the operation. Pyrexia was recorded as the number of 12-h periods in which a temperature greater than 37.3 °C was recorded. The ease of mobility was assessed daily for the first 3 days after operation using a five-point mobilization scale, and a cumulative score was recorded. On the 5th day after operation, the mood state and anxiety level were re-assessed using the same psychological tests used before the operation. Any complications such as chest infection, urinary tract infection or wound infection were recorded. The duration of hospital stay was recorded to the nearest half-day: if the patient was discharged before mid-day, it was counted as a half-day stay and after mid-day the stay would be 1 day. Before discharge, the nursing staff were asked to grade the overall recovery of the patient as "as expected", or better or worse than expected. None of the nurses knew which tape the patient had heard during operation. Parametric data were analysed by analysis of variance and non-parametric data were analysed with Kruskal-Wallis and chi-square tests. P < 0.05 was considered significant. RESULTS
No patient refused the invitation to participate. Two patients were excluded from statistical analysis; one (suggestion group) required further surgery during her stay in hospital and the other patient's operation was cancelled. Consequently, there were 24 patients in the suggestion group (group S), 25 in the history group (group H) and 24 in the blank tape group (group B). There were no significant differences among the three groups in age, weight, preoperative haemoglobin concentration, preoperative mood state or anxiety level, estimated blood loss, duration of operation or the number of times the tape was played (table I). None of the patients had any recall of intraoperative events or dreams. One patient had two episodes of nightmares about her operation and
Downloaded from http://bja.oxfordjournals.org/ at University of California, San Diego on August 19, 2015
Age (yr) t Weight (kg) Haemoglobin concn (gdl- 1 ) Profile of mood states, before op.* Anxiety scores Duration of operation (min) Blood loss (ml) Message played (No. of times) Grade of surgeons Consultants SR/Reg/SHO
Group S (n = 24)
279
THERAPEUTIC SUGGESTIONS DURING ANAESTHESIA
TABLE III. Patients' guesses on messages received and the number of hospital beds, and the nursing assessment of postoperative recovery. No significant difference was found between groups
T ;-.
I
i Ol
patients
20
i
i
° 106 2
500.0
-i
2.0
4.0 6.0 8.0 10.0 Duration of hospital stay (days)
12.0
F I G . 1. Pattern of hospital discharge of patients in suggestion group ( ), history group ( - • • - ) and blank tape group ( • • • • ) •
thought she had listened to the suggestion tape; in fact, she had listened to the tape containing the history of the hospital. There were no differences between groups in the pattern of discharge for all patients (fig. 1). There were no significant differences between the three groups in respect of pyrexia, pain scores, analgesic requirement, nausea, flatulence, mobility, wound or other complications (tables II, III). The patient's guesses of the tape played during operation were not influenced by the tape which had been used. There was no association between the tape heard and patients' estimate of the number of beds in the Queen's Medical Centre. There were no differences in the nurses' assessment of the overall recovery of the patients. DISCUSSION
Neither spontaneous nor prompted recall is of sufficient sensitivity to assess if information presented during anaesthesia adequate for surgical operation is processed, registered, or both, in the anaesthetized brain [1]. Therefore more sophisticated methods such as implicit memory tests [3-5, 13], non-verbal responses [1, 2], hypnosis [14] and improvement in postoperative outcome [8, 9, 15] have been used to provide indirect evidence of information registration during anaesthesia. In earlier studies, reduction in the incidence of postoperative complications and duration of hospital stay were reported in patients who were presented with positive suggestions during anaesthesia [15—17].
Group H (n = 25)
Group B (n = 24)
8 2 14
11 5 9
9 3 12
12 4 8
15 6 4
14 5 5
7 17
9 16
9 15
These findings were supported by the results of studies with better design which involved patients undergoing only one type of operation [8, 9]. Bonke and colleagues suggested that, after cholecystectomy, only patients aged 55 yr or older demonstrated significant improvements; they attributed this to the fact that older patients were more likely to develop secondary complications in the postoperative period [9]. However, when this study was repeated subsequently by the same group of investigators using more control groups, the initial encouraging results were not confirmed [10], despite the use of identical therapeutic suggestions [9]. In another study, improvement in postoperative outcome was also not evident in patients who received therapeutic messages suggesting a rapid recovery, although the number of patients studied was relatively small [18]. More recently, patients who were given therapeutic suggestions during anaesthesia were reported to have significant reduction in requirement for postoperative analgesia, as assessed using a patient-controlled device to provide more objective measure of analgesic requirements [19]. However, the extent of reduction in analgesic requirements was small. In summary, evidence for the ability of intraoperative suggestions to improve postoperative outcome has been conflicting. Evans and Richardson reported that therapeutic suggestions during anaesthesia reduced duration of
TABLE II. Mean (SD) or median (quar tiles) of recovery variables. No significant difference was found between groups
Duration of hospital stay (days) Pyrexia (half-days) Pain intensity (0-100) I.m. analgesia (mg) Oral analgesia (mg) Profile of mood states, after op. Nausea (0-100) Flatulence (0-100) Mobilization (0-15) Wound (0-^1)
Group S (« = 24)
Group H (" = 25)
Group B (n = 24)
6.9(1.3)
6.9(1.6)
6.6(1.1)
5.2 (3.4) 39.7 (20.6) 94.0 (32.5) 23.8(15.6) 69.0
4.4 (2.8) 35.9(14.5) 77.2 (29.2) 20.6(11.8) 70.0
3.8 (2.2) 30.0(17.7) 85.7 (32.9) 18.7(10.8) 68.0
23.7(31.8) 32.7(27.1) 7.6(1.6) 0.7(1.2)
16.3(21.6) 42.6 (28.9) 7.8(1.2) 0.4 (0.8)
22.1 (19.8) 24.8(21.9) 7.8(1.3) 0.4 (0.9)
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Patient guess of tape content Suggestion tape History tape Blank tape Nurses' assessment of recovery As expected Better than expected Worse than expected Patient guess of no. of hospital beds Correct Incorrect
i
Group S (n = 24)
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however, patients in this study who were exposed to the "history of hospital" tape did not perform significantly better than those in the other two groups. Goldman reported significantly better performance in patients who were given answers to specific questions during anaesthesia [25]. However, there are two major differences between Goldman's study and our own: first, the message used in Goldman's study was relatively brief compared with the complicated history of the Queen's Medical Centre; and second, the patients in the present study were not given warning before the operation of the unlikely postoperative question regarding the number of hospital beds. This may suggest that, in order to examine information registered during anaesthesia, the information should be specific and brief, and that the patients should be primed to the type of information they are likely to receive during their operation. Although there is some evidence from previous studies that limited processing of information might occur during anaesthesia, the influence of positive therapeutic suggestions on postoperative outcome is questionable [10, 18]. This may be partly because of the complexity of factors which influence outcome; partly because the variables selected to assess outcome may not be sensitive to differences attributable to therapeutic suggestions; and, finally, because of inter-patient or inter-study variability, or both, in the depth of anaesthesia in various studies. Although it has been suggested that patients should be exposed to positive suggestions routinely during operation in the hope of improving postoperative outcome [7, 8, 21, 22], it is imperative to show that such improvements are readily reproducible. The results of the present study suggest that, in otherwise healthy patients undergoing total abdominal hysterectomy using our anaesthetic technique, there was no evidence of any improvement in postoperative outcome related to either positive therapeutic suggestions or the presence of a voice during anaesthesia. However, this conclusion must be qualified by the fact that the number of patients in this study was very small and it is not possible to exclude the possibility that our findings would be reproduced in a larger study. ACKNOWLEDGEMENT This study was supported financially by a grant from the BUPA MedicaJ Foundation Ltd. REFERENCES 1. Bennett HL, Davis HS, Giannini JA. Non-verbal response to intraoperative conversation. British Journal of Anaesthesia 1985; 57: 174-179. 2. Goldman L, Shah M, Hebden M. Memory of cardiac anaesthesia: Psychological sequelae in cardiac patients of intra-operative suggestions and operating room conversation. Anaesthesia 1987; 42: 596-603. 3. Millar K, Watkinson N. Recognition of words presented during general anaesthesia. Ergonomics 1983; 26: 585-594. 4. Stolzy S, Couture LJ, Edmonds HL jr. Evidence of partial recall during general anesthesia. Anesthesia and Analgesia 1986; 65: S154. 5. Block RI, Ghoneim MM, Sum Ping ST, Ali MA. Human learning during general anaesthesia and surgery. British Journal of Anaesthesia 1991; 66: 170-178.
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hospital stay and postoperative morbidity significantly in patients who had undergone total abdominal hysterectomy [8]. We have been unable to reproduce this result in our study, despite the use of identical therapeutic suggestions in the two studies. Furthermore, Evans and Richardson also reported very accurate guesses by the patients in respect of the tape to which they were exposed to during anaesthesia; all but one patient (18 of 19) in the suggestion group guessed correctly that they had been exposed to intraoperative suggestions. In addition, the pattern of assessments by nursing staff of the overall recovery of the patients matched almost exactly the correct guesses of the patients. These results also were not reproduced in the present study. In the context of preconscious processing of information presented to the anaesthetized brain, it has been suggested that general anaesthesia may cause dissociation between explicit (which requires conscious effort to recall events) and implicit (which does not require any effort) memory [20]. The incidence of implicit memory of information presented or of other intraoperative events during anaesthesia is not known precisely, but it-is likely to be much greater than the incidence of explicit memory [21,22]. Nevertheless, registration of information under anaesthesia is considered to be very fragile, so that, even when sensitive implicit memory tests are applied, the evidence is not robust [5, 23]. Consequently, the high degree of accuracy in patients' guesses and nurses' assessment of the use of the suggestion tape in Evans and Richardson's study was unexpected; indeed, doubts on the double-blind nature of their study have been expressed [24]. However, it is possible that the difference between the two studies can be attributed to differences in depth of anaesthesia either throughout the operation or towards the end of the procedure when volatile agents might have been discontinued before the end of surgery but while the tapes were still being played. A standard anaesthetic technique was not used in Evans and Richardson's study, in that a large variety of different anaesthetic drugs was administered by several anaesthetists. This may have increased the variability in the depth of anaesthesia in different patients, therefore increasing the likelihood of information registration in those who were exposed to suggestion tape in their study. The use of duration of stay as a means of postoperative recovery is open to criticism, in that it may be influenced by many factors, including differences in normal practice among consultant surgeons. In the present study, patients were admitted under the care of one of three surgeons. The distribution of consultant surgeons in each group was: group S—7,9,8; group H—8,8,9; group B—7,9,8. The median duration of stay, irrespective of group, was 6.5 days for patients of all surgical consultants. However, other factors may have influenced the decision to discharge patients from hospital. In addition, this is a very insensitive index of recovery from anaesthesia and surgery. In the present study, the estimation of the number of hospital beds was used as a form of memory test;
BRITISH JOURNAL OF ANAESTHESIA
THERAPEUTIC SUGGESTIONS DURING ANAESTHESIA 17. 18. 19.
20.
21. 22. 23.
24. 25.
a report and evaluation of 200 consecutive cases. American Journal of Clinical Hypnosis 1961; 4: 26-29. Wolfe LS, Millet JB. Control of post-operative pain by suggestion under general anesthesia. American Journal of Clinical Hypnosis 1960; 3: 109-112. Woo R, Seltzer JL, Marr A. The lack of response to suggestion under controlled surgical anesthesia. Acta Anaesthesiologica Scandinavica 1987; 31: 567-571. McLintock TTC, Aitken H, Downie CFA, Kenny GNC. Postoperative analgesic requirements in patients exposed to positive intraoperative suggestions. British Medical Journal 1990; 301: 788-790. Kihlstrom JF, Schacter DL. Anaesthesia, amnesia and the cognitive unconscious. In: Bonke B, Fitch W, Millar K, eds. Memory and Awareness in Anaesthesia. Amsterdam: Swets, 1989: 21-44. Jones JG, Konieczko K. Hearing and memory in anaesthetized patients. British Medical Journal 1986; 292: 12911293. Griffiths D, Jones JG. Editorial I. Awareness and memory in anaesthetized patients. British Journal of Anaesthesia 1990; 65: 603-606. Millar K. Memory during anaesthesia. In: Gruneberg MM, Morris PE, Sykes RN, eds. Practical Aspects of Memory : Current Research and Issues, Vol. II, Clinical and Educational Implications. New York: John Wiley, 1987. Mackie DS. Therapeutic suggestions during general anaesthesia. Lancet 1988; 2: 955-956. Goldman L. Awareness under general anaesthesia (Ph.D. dissertation). Cambridge: University of Cambridge, 1986.
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6. Goldmann L. Information processing under general anaesthesia : a review. Journal of the Royal Society of Medicine 1988; 81: 224-227. 7. Editorial. Advertising during anaesthesia? Lancet 1986; 2: 1019-1020. 8. Evans C, Richardson PH. Improved recovery and reduced postoperative stay after therapeutic suggestions during general anaesthesia. Lancet 1988; 2: 491^193. 9. Bonke B, Schmitz PIM, Verhage F, Zwaveling A. Clinical study of so-called unconscious perception during general anaesthesia. British Journal of Anaesthesia 1986; 58: 957-964. 10. Boeke S, Bonke B, Bouwhuis-Hoogerwerf ML, Bovill JG, Zwaveling A. Effects of sounds presented during general anaesthesia on postoperative course. British Journal of Anaesthesia 1988; 60: 697-702. 11. McNair DM, Lorr M, Droppleman LF. Profile of Mood States Manual. San Diego: Educational and Industrial Testing Service, 1971. 12. Spielberger CD, Gorsuch RL, Lushene RE. State-Trait Anxiety Inventory Manual. California: Consulting Psychologists Press Inc., 1970. 13. Eich E, Reeves JL, Katz RL. Anesthesia, amnesia and the memory/awareness distinction. Anesthesia and Analgesia 1985; 64: 1143-1148. 14. Levinson BW. States of awareness during genera] anaesthesia. British Journal of Anaesthesia 1965; 37: 544-546. 15. Pearson RE. Response to suggestions given under general anesthesia. American Journal of Clinical Hypnosis 1961; 4: 106-114. 16. Hutchings D. The value of suggestion given under anesthesia:
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