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Conscious awareness during general anaesthesia: patients' perceptions, emotions, cognition and reactions
British Journal of Anaesthesia 1998; 80: 133–139
CLINICAL INVESTIGATIONS
Conscious awareness during general anaesthesia: patients’ perceptions, emotions, cognition and reactions D. SCHWENDER, H. KUNZE-KRONAWITTER, P. DIETRICH, S. KLASING, H. FORST AND C. MADLER
Summary We interviewed 45 patients, who answered advertisements (n : 21) or were referred by colleagues (n : 24), about their experience of intraoperative awareness using a standardized questionnaire. Auditory perceptions, hearing sounds or voices were mentioned by all patients (45 of 45): 33 of 45 patients understood and recalled conversations; 21 of 45 patients had visual perceptions; 12 of 21 recognized things or faces; 29 of 45 patients felt being touched; three patients had the sensation of moderate pain; and eight patients were in severe pain. Patients’ feelings were mostly related to paralysis (27 of 45), helplessness (28 of 45), anxiety and fear (22 of 45); 18 were in severe panic. All patients (45 of 45) recognized the situation as a real event: 22 of 45 patients experienced unpleasant after effects; 11 suffered from anxiety and nightmares; and three developed post-traumatic stress disorder syndrome and required medical treatment. Twenty of 45 patients were especially attentive to emotionally relevant remarks on their own person, their disease and the course of their operation. The accuracy of sensory perception indicates a very high level of cognitive performance of patients during intraoperative awareness. (Br. J. Anaesth. 1998; 80: 133–139) Keywords: anaesthesia, general; memory; psychological responses
anaesthesia,
depth;
The incidence of awareness during general anaesthesia that can be recalled explicitly after operation has been reported to be 0.5–2%.1–9 Patients waking up during their anaesthetic are awake, in agony, intensely fearful but completely helpless, thinking that something must have gone terribly wrong. After operation, they recall all of the details of the procedure and the shock of this experience may cause post-traumatic stress disorder (PTSD).9–11 Characteristic symptoms of PTSD involve reexperiencing the event, sleep disturbances with recurrent nightmares, avoidance of stimuli associated with the event, numbing of general responsiveness or increased arousal, anxiety and preoccupation with death, that in some cases require long-term medical and psychological support or treatment.9 12 Information on what patients perceive and recall of events during general anaesthesia is based mostly on case reports.13–21 Most of these case reports relate to
the patient’s actual experience rather than patient reactions or after effects of awareness. Consequences of intraoperative awareness have been described only on the basis of small series of patients.22–29 Only two studies analysed patients’ feelings during, and patients’ reactions to, awareness. Evans studied 27 patients with recall after anaesthesia having selected his patients by advertising in four British newspapers.30 Bias of this sample cannot be excluded because advertisements select a disproportionate number of patients with a strong interest in their own medical history (so-called complainers). Therefore, Moerman, Bonke and Oosting investigated 26 patients with experiences of awareness during anaesthesia referred by colleagues of the anaesthesia department of a large university hospital.31 In this study we have investigated two groups of patients with experiences of awareness. One group was collected from advertisements in four German newspapers and the Internet. Patients in the second group were referred by colleagues of the anaesthesia departments of one large university hospital and two large community hospitals. The incidence, quality, intensity and accuracy of sensory perceptions, emotions and feelings, cognition and realization, reactions, consequences and after effects during and after intraoperative awareness was assessed within and between groups.
Patients and methods After obtaining approval from the local Ethics Committee, two groups of patients with experience of awareness during general anaesthesia were collected. In group 1, patients answered advertisements placed in four German newspapers and on the Internet. The text of the advertisement was as follows: “For scientific research and documentation on the subject of ‘awake during general anaesthesia?’ the Department of Anaesthesia of Munich University and the Science Department of the German state television, section SDR, are looking for patients who woke up D. SCHWENDER*, MD, H. KUNZE-KRONAWITTER, MD, P. DIETRICH, MD, S. KLASING, Institute for Anaesthesiology, University of Munich, FRG. H. FORST, MD, Institute for Anaesthesiology, Klinikum Augsburg, FRG. C. MADLER, MD, Institute for Anaesthesiology, Klinikum Kaiserslautern, FRG. Accepted for publication: September 22, 1997. *Address for correspondence: Institute for Anaesthesiology, Ludwig-Maximilians-University, Munich, Klinikum Innenstadt, Nubaumstrae 20, 80336 München, Germany.
British Journal of Anaesthesia 1998; 80: 133–139
Time interval
12 yr
20 yr
2 yr
21 yr
4 yr 26 yr
30 yr
7 yr
4 yr
17 yr
2 yr
2 yr
19 yr
2 yr
5 yr
4 yr
20 yr 9 yr
16 yr
5 yr
2
3
4
5
6 7
8
9
10
11
12
13
14
15
16
17
18 19
20
21
Group 1 1 13 yr
Patient No.
M, 55 yr, 174 cm, 75 kg
F, 46 yr, 168 cm, 70 kg
F, 44 yr, 164 cm, 77 kg M, 49 yr, 176 cm, 77 kg
F, 33 yr, 171 cm, 86 kg
F, 55 yr, 159 cm, 59 kg
F, 33 yr, 155 cm, 82 kg
M, 56 yr, 179 cm, 80 kg
F, 46 yr, 161 cm, 95 kg
M, 55 yr, 198 cm, 90 kg
F, 23 yr, 163 cm, 47 kg
F, 58 yr, 168 cm, 73 kg
F, 45 yr, 163 cm, 63 kg
F, 40 yr, 167 cm, 65 kg
M, 47 yr, 176 cm, 140 kg F, 63 yr, 158 cm, 65 kg
F, 63 yr, 163 cm, 55 kg
F, 24 yr, 162 cm, 60 kg
M, 63 yr, 169 cm, 84 kg
M, 26 yr, 194 cm, 85 kg
F, 31 yr, 160 cm, 80 kg
Patients’ data (sex, age, height, weight)
Aortocoronary bypass
Caesarean section (emergency)
Abortion curettage Aortocoronary bypass (emergency)
Caesarean section (emergency)
Multiple trauma (emergency)
Caesarean section (emergency)
Anal fissure
Operation of the cervical spinal column
Parotid tumour
Herniorrhaphy
Lower extremity fracture
Cardiac valve replacement
Operation on external ear
Arthroscopy knee Caesarean section
Nephrostomy
Cholecystectomy
Total hip replacement
Operation of a funnel breast
Dental surgery
Operation
Table 1 Case reports, patient data, perceptions, feelings and sequelae
Heard people talking: “Stop, she is waking up, she needs some more anaesthetic”, saw silhouettes, no pain, no anxiety Felt hands and arms during being positioned and heard voices say: “we won’t get along this way, we have to lay him down” Heard voices and the sound of metal, saw silhouettes and felt that his leg was moved up and down, moderate pain, helpless, in panic, tried to alert someone Heard voices, felt no pain, helpless and in panic, paralysed, tried to open eyes and to alert someone Heard voices and the sound of metal, unable to open eyes, no pain, no anxiety Heard a voice saying: “how can a man be so fat” Felt skin incision and touch, unbearable pain, heard: “she moves, she is coughing”, saw silhouettes, felt paralysed, helpless, in panic, tried to alert someone Heard sounds and understood conversation, no pain, clear sight, tried to alert someone, felt paralysed Heard the sound of metal and a voice saying: “the patient tries to move. He is waking up!” tried to move finger, felt paralysed, unable to open eyes, tried to talk, felt helpless, no fear, no pain Heard voices, felt skin incision and unbearable pain, saw silhouettes, unable to move, helpless, tried to alert someone Moved arm and heard voice saying: “she is awake, she needs more anaesthetic” no anxiety, no pain Heard voices talking about the patient’s increase in blood pressure, no anxiety, no panic, no pain Recalled conversation concerning her overweight: “how can a women be so fat?” and other disgusting jokes about her body weight Heard voices and understood conversation about how he lay on the operation table Heard: “She is awake” saw silhouttes, unable to open eyes, felt unbearable pain, paralysed, helpless, in panic, tried to alert someone Heard voices and conversation of medical staff, saw light, silhouettes, no pain Felt pain during skin incision, heard conversation: “What about the suction device?” Tried to move, felt paralysed, saw lights and silhouettes Heard sounds, saw light, no pain, felt paralysed, helpless, in panic Heard and recalled conversation during emergency defibrillation, felt the electrical shocks and heard a voice saying: “We won’t get him”, panic Heard sounds and conversation, able to understand and recall conversation, no pain, heard the sound of the crying baby after delivery Heard sounds, understood conversation, no pain, felt paralysed
Perceptions during intraoperative awareness
Anxiety, depression unable to stay in his job as an electrician, post-traumatic stress disorder
None
None Severe anxiety, post-traumatic stress disorder, psychotherapy
Nightmares and sleep disturbances for 2 yr
Nightmares, increased fear for future anaesthetics and operations None
None
Depression for several weeks
Nightmares, could not stay in bed after waking up None
None
Nightmares, anxiety of being unable to open eyes, for instance, when driving a car
None
None Increased fear for future anaesthetics and operations
None
None
Exaggerated sensitivity to sounds for 1.5 yr
None
None
Sequelae
134 British Journal of Anaesthesia
Time interval
5 yr
16 yr
4 yr
5 yr 1 yr
20 yr
7 yr
10 yr
6 month
1 yr
10 yr
1 yr
21 yr
1 yr 8 yr
6 yr
8 yr 6 yr 10 yr
11 yr
2 month 4 month 4 month
2
3
4
5 6
7
8
9
10
11
12
13
14
15 16
17
18 19 20
21
22 23 24
Group 2 1 2 yr
Patient No.
F, 37 yr, 165 cm, 72 kg F, 43 yr, 162 cm, 62 kg M, 64 yr, 172 cm, 68 kg
F, 38 yr, 172 cm, 80 kg
M, 50 yr, 181 cm, 80 kg F, 29 yr, 168 cm, 72 kg F, 25 yr, 165 cm, 59 kg
F, 34 yr, 165 cm, 79 kg
M, 14 yr, 161 cm, 54 kg F, 34 yr, 175 cm, 68 kg
F, 30 yr, 172 cm, 58 kg
M, 43 yr, 180 cm, 86 kg
F, 60 yr, 174 cm, 93 kg
F, 46 yr, 166 cm, 80 kg
M, 44 yr, 182 cm, 85 kg
M, 24 yr, 170 cm, 80 kg
F, 39 yr, 159 cm, 74 kg
M, 45 yr, 179 cm, 74 kg
F, 36 yr, 162 cm, 63 kg F, 34 yr, 170 cm, 70 kg
M, 35 yr, 180 cm, 80 kg
F, 37 yr, 167 cm, 42 kg
F, 33 yr, 169 cm, 52 kg, (anaesthetist)
F, 52 yr, 168 cm, 73 kg, (anaesthetist)
Patients data (sex, age, height, weight)
Laparoscopic cholecystectomy Laparoscopy Cholecystectomy
Appendicectomy (emergency)
Aortocoronary bypass Caesarean section (emergency) Dental surgery
Appendicectomy
Gastroscopy Caesarean section (emergency)
Tonsillectomy
Dental surgery
Laparatomy, peritonitis (emergency)
Meniscectomy
Appendicectomy (emergency)
Upper extremity fracture
Caesarean section (emergency)
Septorhinoplasty
Multiple trauma, laparatomy (emergency) Laparoscopic cholecystectomy Thyroidectomy
Appendicectomy (emergency)
Excisional biopsy, breast tumour
Abdominal hysterectomy, anaphylactic shock (emergency)
Operation
Table 1 Case reports, patient data, perceptions, feelings and sequelae—continued
British Journal of Anaesthesia 1998; 80: 133–139
None
None None
Increased fear of future operations or anaesthetics Fear to die
None
None
Sequelae
Sleep disturbances, fear to die, post-traumatic stress disorder, psychotherapy Felt intratracheal tube, heard voices and conversation: “Now we can None start with the operation”, tried to open eyes, felt paralysed, no pain Heard voices, felt painful skin incision, paralysed, helpless, tried to None alert someone Heard conversation: “We now take a photo and show it to her None afterwards”, felt hands touching her, helpless, paralysed, panic Heard surgeons saying: “Why do we always have to treat the Anxiety, nightmares complications of other medical centres? This woman is lost anyhow.” Heard the surgeon saying something to the anaesthetist, saw the None surgical gloves as a silhouette Felt her mouth being opened, could understand conversation and None recognised the surgeon, the medical staff and the operating theatre. Moderate pain Heard conversation, felt touch, felt suffocated and paralysed None Felt being touched, tried to alert someone, felt paralysed, heard None voices Heard the surgeon saying: “She needs some more anaesthetic, None because she is a red haired nurse and everything is different and very special in her case.” Heard voices, saw lights and silhouettes None Felt being touched, heard the sound of the crying baby None Opened eyes, saw the surgeon, who went to call for the anaesthetist, None saying: “She needs some more anaesthetics.” Felt the tracheal tube and heard the surgeon saying: “The appendix None is shortly before perforating.” Felt the tracheal tube, felt helpless, anxious None Heard the voice of the anaesthetist, unable to open eyes None Felt tracheal tube, heard voices None
Heard the word: “You have to give epinephrine, realized the emergency situation, thinking this is no more routine management, guys you are in severe difficulties, but I am sure, that you are doing the right things, giving epinephrine”, no anxiety, no pain High-dose fentanyl anaesthesia, awake during the whole surgical procedure, heard sounds and conversation, saw silhouettes and felt being touched during the operation, no pain, no anxiety Heard sounds and voices: “Can we start with the operation now?” Tried to alert someone, felt paralysed, helpless, in panic, no pain, Heard voices, saw silhouettes, no pain, felt helpless and paralysed, in panic, thought: “Now I have to die”, tried to alert someone Painful feeling in the upper abdomen, tried to move, felt paralysed Heard voices saying: “the tube is too big but, we do not have another”, no pain Heard sounds, opened eyes, saw surgeon and light, felt pressure on his head, no pain Felt warm fluid flowing over her abdomen, tried to open eyes, fear of bleeding to death
Perceptions during intraoperative awareness
Awareness during general anaesthesia 135
136 during surgery while the operation was going on. Your experience will be an important contribution to our work. Please contact us. Your replies will be regarded as confidential. Please reply to SDR, ScienceDepartment 68028 Mannheim/Germany.” Patients in group 2 were referred by colleagues of the anaesthesia departments of a large university hospital (Institute for Anaesthesiology, LudwigMaximilians-University Munich, Klinikum Innenstadt) and two large community hospitals (Institute for Anaesthesiology, Klinikum Augsburg and Institute for Anaesthesiology, Klinikum Kaiserslautern) requesting that they refer all patients with experience of awareness regardless of when the experience had occurred or the anaesthesia had taken place. All patients in the two groups were interviewed using our standardized questionnaire “Awareness during general anaesthesia”. The questionnaire was subdivided into six sections: personal data, detailed description in own words, sensory perceptions, feelings and emotions, cognition and interpretations, reactions, consequences and after effects. The following data were collected. (1) Personal data: patient’s name and address, age, sex, height, body weight, date, place and type of surgery, and preoperative feelings of nervousness, anxiety and pain. (2) In the second section, patients were allowed to give a detailed description in their own words of perceptions, feelings and thinking while being awake during the anaesthetic. (3) Incidence, quality, intensity and accuracy of sensory perceptions within the different sense modalities. Auditory modality: loud, low, close, far away, identification of the direction of the sound source, recognition of sounds or voices, understanding of language and conversation. Visual modality: able to describe light, shades, silhouettes, clearly or everything looking hazy, able to recognize things or people, either isolated or within a visual context. Tactile modality: feeling of being touched, quality and localization of sensation. Paralysis: unable to move arms, legs, head, vocal cords or other sites. Nociceptive modality: feeling pain, intensity, ranging from none, moderate to severe (0, 1, 2), identification of painful body part. (4) Feelings and emotions differentiated into helplessness, weakness, fear and panic, with intensity ranging from none, moderate to severe (0, 1, 2). (5) Interpretation of the situation and cognition, interpretation as dream or reality, estimation of duration and whether patient is trying to alert anyone or make signs. (6) Patients’ reactions, consequences for daily life and after effects: anxiety, fears, nightmares with intensity ranging from none, moderate to severe (0, 1, 2). Other consequences for daily life such as re-experiencing the event, numbing of general responsiveness, increased arousal, loneliness and lack of confidence in future life. Changing of opinion on anaesthesia and surgery and fear of repetition or more fear of future anaesthetics or surgeries. Duration of symptoms and whether the symptoms required medical treatment or a PTSD syndrome developed.
British Journal of Anaesthesia The last question was whether the patient informed the anaesthetist, surgeon, ward staff, general practitioner, partner, family or friends and what was their reaction. STATISTICAL ANALYSES
Data are presented as mean (SD). For differences between groups, groups were compared using the Mann–Whitney U or chi-square test. Subgroups of patients were compared using chi-square or Fisher’s exact test (two-sided). Differences were considered significant if P : 0.05, after Bonferroni’s correction for multiple comparisons.
Results During an 8-month period, 45 patients were analysed; 21 patients replied to the advertisements (group 1) and 24 patients were referred from the three hospitals involved in the study (group 2). In total, 45 questionnaires of awareness during general anaesthesia were analysed. In table 1, case reports, patient data, a short description of patients’ perceptions and feelings, and postoperative sequelae are presented. The two groups were comparable in patient data, type of surgery, a wide range of incidence, quality, intensity and accuracy of perceptions, emotions, cognition, reactions and after effects. Details on patients (sex, age, weight, height, time interval between interview and anaesthesia), type of surgery, patients’ descriptions of their experiences of awareness in keywords and postoperative sequelae are presented in table 1. Mean age of the patients was 41.7 (range 14–64) yr, mean body weight was 73.9 (47–140) kg and body height 169.75 (153–194) cm. Thirty patients were female and 15 male, and the time interval between the event and the interview was 9.6 yr (range 0.1–30 yr). Events occurred during anaesthesia for elective general abdominal (n:16), cardiothoracic (n:5), orthopaedic (n:6), gynaecological (n:4) or ear–nose–throat or dental surgery (n:7). Seven cases of awareness were observed during Caesarean section and 14 patients underwent emergency surgical procedures. In table 2 the incidence, quality, intensity and accuracy of perceptions, emotions, cognition, reactions and after effects are presented for group 1, group 2 and for both groups combined. SENSORY PERCEPTIONS WITHIN THE DIFFERENT SENSE MODALITIES
All patients (45 of 45) had auditory perceptions, hearing sounds or voices. The sound source was described as loud in 28 of 45 and close in 29 of 45 patients; 33 of 45 patients understood and recalled conversations. Patients in group 1 heard the sounds louder and closer when being aware and were significantly more often able to understand conversations; 21 of 45 had visual perceptions, and 10 of these 21 described their vision as clear, while 10 patients saw only silhouettes. Twelve patients recognized things or faces and 10 were able to localize this in the visual context of the operating room. Twenty-nine patients felt being touched, 28 of these were able to localize exactly where they felt the touch. Thirty-four
Awareness during general anaesthesia patients felt no pain, three patients felt moderate and eight patients severe pain. All patients with pain perceptions were able to localize exactly were they felt the pain. Twenty-seven patients had the feeling of paralysis, 22 of whom were able to localize the paralysed body parts. EMOTIONS
Twenty-eight of 45 patients felt helpless, 22 of 45 had feelings of anxiety and fear, four had moderate fear and 18 were in severe panic. COGNITION
All patients (45 of 45) recognized their situation as a real event. The estimated duration of the awareness episode during anaesthesia ranged from 1 to 60 min (mean duration 7.73 min). Thirty-one of 45 patients tried to alert someone or to make signs.
137 nightmares more often and after effects lasted significantly longer compared with those in group 2. Forty of 45 patients informed the anaesthetist, surgeon, medical staff, family or friends after operation. The response appeared to be affirmative, ranging from sympathy and explanation (19 of 40), or defensive, ranging from disbelieve to denial (10 of 40). We subdivided all patients into two groups and compared those patients with and without after effects. Almost all patients with after effects had changed their opinion on anaesthesia and surgery (P : 0.001). Patients with after effects were significantly more often helpless (P : 0.001) and in fear or severe panic (P : 0.049) when being aware during operation compared with patients without after effects. There was no difference between patients with and without after effects regarding incidence and intensity of pain perception (P : 0.856) and other sensory perceptions, emotions and cognition.
Discussion REACTIONS AND AFTER EFFECTS
Twenty-two of 45 patients suffered from after effects of their awareness episode; 21 changed their opinion on future anaesthetics and operations, 11 suffered from anxiety during the day and 11 suffered from nightmares. In nine patients the awareness episode had consequences for their daily life, three required medical treatment and three patients developed PTSD syndrome. The mean duration of after effects was 0.84 (range 0.1–5.0) yr. Patients in group 1 had
The two patient groups (21 patients who answered the advertisement (group 1) and 24 patients referred by colleagues of the large hospitals (group 2)) were comparable in patient data, type of surgery, a wide range of perceptions, emotions and cognition during their awareness episode, and incidence of after effects. Differences were found only in the quality of auditory perception and the incidence of understanding of language. Patients in group 1 heard the sounds louder and closer and were significantly more
Table 2 Incidence, quality, intensity and accuracy of perceptions, emotions, cognition, reactions and after effects. *P:0.05; **P:0.01 (chi-square test)
Auditory perception Intensity loud** Distance close* Understanding language, recall conversation* Visual perception Quality of visual perception clear Recognition of things, faces within a visual context Tactile perception localisation of tactile perception Pain perception moderate Pain perception severe localisation of pain Paralysis localisation of paralysis Helplessness Anxiety moderate Anxiety severe panic Recognition as real event estimated duration of awareness (min) (mean (SD)) Tried to alert someone After effects Duration of after effects** (yr) (mean (SD)) Changed opinion Anxiety Nightmares** Consequences for daily life Medical treatment Post-traumatic stress disorder Informed other people Anaesthetist Surgeon Ward staff General practitioner Family/friends Response of other people affirmative (sympathy to explanation) Response of other people defensive (disbelief to denial) Response of other people no detail
Group 1 n (%)
Group 2 n (%)
Group 1;2 n (%)
21 (100.0) 17 (80.9) 18 (85.7) 18 (85.7) 11 (52.4) 5 (45.5) 6 (54.5) 4 (36.4) 14 (66.7) 13 (92.9) 1 (4.8) 6 (28.6) 7 (100.0) 13 (61.9) 11 (84.6) 13 (61.9) 1 (4.8) 10 (47.6) 21 (100.0) 9.46 (6.08) 16 (76.2) 11 (52.4) 1.59 (1.93) 10 (83.3) 6 (66.7) 8 (80.0) 7 (63.6) 2 (18.2) 2 (18.2) 19 (90.5) 10 (52.6) 12 (63.2) 7 (36.8) 4 (21.1) 14 (77.8) 8 (42.1) 5 (26.3) 6 (31.6)
24 (100.0) 11 (45.8) 11 (45.8) 15 (62.5) 10 (41.7) 5 (50.0) 6 (60.0) 6 (60.0) 15 (62.5) 15 (100.0) 2 (8.3) 2 (8.3) 4 (100.0) 14 (58.3) 11 (78.6) 15 (62.5) 3 (12.5) 8 (33.3) 24 (100.0) 6.00 (13.1) 15 (62.5) 11 (45.8) 0.08 (0.15) 11 (100.0) 5 (45.5) 3 (27.3) 2 (18.2) 1 (10.0) 1 (10.0) 21 (87.5) 13 (61.9) 7 (33.3) 5 (23.8) 2 (10.5) 9 (45.0) 11 (52.4) 5 (23.8) 5 (23.8)
45 (100.0) 28 (62.2) 29 (64.4) 33 (73.3) 21 (46.7) 10 (47.6) 12 (57.1) 10 (47.6) 29 (64.4) 28 (96.6) 3 (6.7) 8 (17.8) 11 (100.0) 27 (60.0) 22 (81.5) 28 (62.2) 4 (8.9) 18 (40.0) 45 (100.0) 7.32 (14.17) 31 (68.9) 22 (48.9) 21 (91.3) 11 (55.0) 11 (52.4) 9 (40.9) 3 (14.3) 3 (14.3) 40 (88.9) 23 (57.5) 19 (47.5) 12 (30.0) 6 (15.8) 23 (60.5) 19 (47.5) 10 (25.0) 11 (27.5)
138 often able to understand conversations. One important difference between groups was that group 1 patients had nightmares more often and after effects lasted significantly longer than in group 2 (mean duration 1.59 vs 0.08 yr). This may be because of a bias in patient collection, indicating that patients who answered the advertisements had severer and longer lasting postoperative sequelae and possibly a stronger interest in their own medical history (so-called complainers). Our data support the suggestion of Moerman, Bonke and Oosting that it cannot be excluded completely that by advertising, a patient sample is biased and a disproportionate number of “complainers” may be selected with a strong personal interest in their own medical history.31 As in the studies of Moerman, Bonke and Oosting31 and Evans,30 reports of awareness during anaesthesia in our analyses occurred not only during “high risk awareness” surgical procedures such as obstetric, cardiac or emergency surgery. The majority of awareness cases in our study occurred during elective ear, nose, throat, dental, general, abdominal, orthopaedic or gynaecological surgery, indicating that awareness during anaesthesia is not only a problem of special surgical procedures but may occur occasionally during anaesthesia for almost any elective procedure. The incidence of perceptions within the different modalities during intraoperative awareness correspond well with data reported in the literature.1 9 15 24 26 27 30 32 All patients were able to hear, indicating that the auditory modality is the most important sensory channel during intraoperative awareness. A high percentage of patients, especially those who heard loud sounds with the sound source close by, were able to understand language and remember conversations after operation. Twenty patients were especially attentive to emotionally relevant remarks, that is they recalled remarks on their own person, disease and course of the operation (two cases of derogatory remarks, two cases of very meaningful remarks and 15 cases of some type of meaningful remarks). This finding may support a widespread belief that meaningful words and remarks are recalled more easily than neutral sounds and have a greater impact on the patient.25 28 29 32–36 On the other hand, 25 patients recalled only general theatre chat and noise. Visual perception was reported by nearly 50% of our patients. This experience has been rarely documented and exceeds incidences reported by Moerman, Bonke and Oosting (27%) and Evans (33%). Furthermore, 50% of our patients with intraoperative visual perceptions had clear sight and could recognize things and faces within a clear visual context of their visual field. A high percentage of patients had tactile sensations and almost all were able to localize the body parts exactly where they were being touched. The high incidence of paralysis in our study corresponds well with data from the literature and in almost all cases the paralysed body parts could be identified. The incidence of pain perception in our study (25%) was less than that reported in the literature (40%).30 31 Nevertheless, 17.8% of patients had severe pain. All patients were able to localize the body part exactly where the painful stimuli occurred.
British Journal of Anaesthesia Jones estimated the incidence of conscious awareness with pain to be lower than 1 in 3000 anaesthetics, and the incidence of conscious awareness without pain perception to be 1–3 in 300 anaesthetics.9 This would imply that painful feelings occur in less than 10% of patients who are aware during anaesthesia. Our data and those of Moerman, Bonke and Oosting, and Evans exceed this estimate; this may be a result of the small sample size and the possible disproportionate number of “complainers” in our study. Two-thirds of patients had emotional distress during their intraoperative awareness and felt helpless or anxious; 40% felt severe distress and panic, an incidence significantly lower than that reported by Moerman, Bonke and Oosting (92%)31 and Evans (78%).30 The percentage of patients who suffered after effects (50%) was slightly lower than in the study of Moerman, Bonke and Oosting.31 Their symptoms corresponded with those reported in the literature.9–12 22 28 37–40 Anxiety during the day, nightmares and sleep disturbances with consequences for daily life were most frequently mentioned. Most often, patients with after effects changed their opinion on anaesthesia and surgery with more fear for future procedures and that such an episode could happen again. Three patients required medical treatment after operation because of the development of PTSD. Why some patients experience after effects or develop PTSD and others do not cannot be explained from the present data. In contrast with Moerman, Bonke and Oosting,31 we did not find a trend towards a correlation between intraoperative pain perception and the incidence of after effects in our patients. Nevertheless, our patients with after effects felt significantly more helpless, fearful or severe panic during operation than patients without after effects. The percentage of patients who informed an anaesthetist, surgeon, hospital staff, family or friends (89%) was higher in our study than reported previously.30 31 This may reflect the increasing popularity that the topic of awareness during anaesthesia has gained in the lay press within the past years and the growing general knowledge of such problems. In contrast with Moerman, Bonke and Oosting, and Evans, responses were mostly affirmative, ranging from sympathy to explanation of the event, although responses of disbelief and denial occurred in some cases. These observations may indicate a steadily increasing understanding of the phenomenon and problems of intraoperative awareness on the part of the patient in addition to anaesthetists and surgeons. In summary, our data indicated a high accuracy of sensory perceptions, especially auditory perceptions, understanding and recall of conversations, and a high level of cognitive performance of patients during intraoperative awareness. The results illustrate the need for the anaesthetic and operating theatre staff to realize that awareness may be occurring during general anaesthesia.
References 1. Agarwal G, Sikh SS. Awareness during anaesthesia–A prospective study. British Journal of Anaesthesia 1977; 49: 835–838.
Awareness during general anaesthesia 2. Brice DD, Hetherington RR, Utting JE. A simple study of awareness and dreaming during anaesthesia. British Journal of Anaesthesia 1970; 42: 535–542. 3. Crawford JS. Awareness during operative obstetrics under general anaesthesia. British Journal of Anaesthesia 1971; 43: 179–182. 4. Harris TJB, Hetherington RR. Dreaming associated with anaesthesia: the influence of morphine premedication and two volatile adjuvants. British Journal of Anaesthesia 1971; 43: 172–178. 5. Hutchinson R. Awareness during surgery. British Journal of Anaesthesia 1960; 33: 463–469. 6. Liu WHD, Thorp TAS, Graham SG, Aitkenhead AR. Incidence of awareness with recall during general anaesthesia. Anaesthesia 1991; 46: 435–437. 7. Lyons G, MacDonald R. Awareness during caesarean section. Anaesthesia 1991; 46: 62–64. 8. Wilson SL, Vaughan RW, Stephen CR. Awareness, dreams and hallucinations associated with general anesthesia. Anesthesia and Analgesia 1975; 54: 609–617. 9. Jones JG. Perception and memory during general anaesthesia. British Journal of Anaesthesia 1994; 73: 31–37. 10. Pedersen T, Johansen H. Serious morbidity attributable to anaesthesia, consideration for prevention. Anaesthesia 1989; 44: 504–508. 11. Macleod AD, Maycock E. Awareness during anaesthesia and post traumatic stress disorder. Anaesthesia in Intensive Care 1992; 20: 12. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. Washington DC: American Psychiatric Association, 1987; 247–251 13. Bogetz MS, Katz JA. Recall of surgery for major trauma. Anesthesiology 1984; 61: 6–9. 14. Aitkenhead AR. Conscious awareness. In: Bonke B, Fitch W, Millar K, eds. Memory and Awareness in Anesthesia. Amsterdam/Lisse: Sweats and Zeitlinger, 1990; 386–399. 15. Jones JG. Hearing and memory in anaesthetised patients. British Medical Journal 1986; 292: 1291–1293. 16. Mark JB, Greenberg LM. Intraoperative awareness and hypertensive crisis during high-dose fentanyl–diazepam– oxygen anesthesia. Anesthesia and Analgesia 1983; 62: 698–700. 17. Mummaneni N, Rao TLK, Montoya A. Awareness and recall with high-dose fentanyl–oxygen anesthesia. Anesthesia and Analgesia 1980; 59: 948–949. 18. Schäfer H-G, Marsch SCU. Wach in totaler intravenöser Anaesthesie. (Fallberichte). Anaesthesist 1990; 39: 617–618. 19. Schwender D, Klasing S, Madler C, Pöppel E, Peter K. Midlatency auditory evoked potentials indicate wakefulness during caesarean section. European Journal of Anaesthesia 1995; 11: 147–148. 20. Tunstall ME. Detecting wakefulness during general anaesthesia for Caesarean section. British Medical Journal 1977; 1: 1321. 21. Jeffrey SK, Raymond CR. Intraoperative awareness with propofol–oxygen total intravenous anesthesia for microlaryngeal surgery. Anesthesiology 1992; 77: 207–209.
139 22. Blacher RS. The hidden psychosis of open-heart surgery with a note on the sense of awe. Journal of the American Medical Association 1972; 222: 305–308. 23. Blacher RS. On awakening paralyzed during surgery. Journal of the American Medical Association 1975; 234: 67–68. 24. Blacher RS. Awareness during surgery. Anesthesiology 1984; 61: 1–2. 25. Cheek DB. Unconscious perception of meaningful sounds during surgical anesthesia as revealed under hypnosis. American Journal of Clinical Hypnosis 1959; 1: 101–113. 26. Cheek DB. The anesthetized patient can hear and can remember. American Journal of Proctol 1962; 13: 287–290. 27. Cheek DB. Further evidence of persistence of hearing under chemo-anesthesia: detailed case report. American Journal of Clinical Hypnosis 1964; 7: 55–59. 28. Cheek DB. Surgical memory and reaction to careless conversation. American Journal of Clinical Hypnosis 1966; 8: 275–280. 29. Levinson BW. States of awareness during general anaesthesia. British Journal of Anaesthesia 1965; 37: 544–546. 30. Evans JM. Patients’ experiences of awareness during general anaesthesia. In: Rosen M, Lunn JN, eds. Consciousness, Awareness and Pain in General Anaesthesia. London: Butterworth, 1987; 184–192. 31. Moerman N, Bonke B, Oosting J. Awareness and recall during general anesthesia. Anesthesiology 1993; 79: 454–464. 32. Ghoneim MM, Block RI. Learning and consciousness during general anesthesia. Anesthesiology 1992; 76: 279–305. 33. Millar K, Watkinson N. Recognition of words presented during general anaesthesia. Ergonomics 1983; 26: 585–594. 34. Dixon NF. Unconscious perception and general anaesthesia. In: Jones JG, ed. Clinical Anaesthesiology, vol. 3 No. 3. London: Bailliere Tindall, 1989; 473–485. 35. Goldmann L. Information processing under general anaesthesia: a review. Journal of the Royal Society of Medicine 1988; 81: 224–227. 36. Griffiths D, Jones JG. Awareness and memory in anaesthetized patients. British Journal of Anaesthesia 1990; 65: 603–606. 37. Utting JE. Clinical aspects of awareness during anaesthesia. In: Bonke B, Fitch W, Millar K, eds. Memory and Awareness in Anaesthesia. Amsterdam/Lisse: Swets and Zeitlinger, 1990; 259–271. 38. Guerra F. Awareness and recall. Neurological and psychological complications of surgery and anesthesia. International Anesthesiology Clinics 1986; 24: 75–99. 39. Bonke B. Psychological consequences of so-called unconscious perception and awareness in anaesthesia. In: Bonke B, Fitch W, Millar K, eds. Memory and Awareness in Anaesthesia. Amsterdam/Lisse: Swets and Zeitlinger, 1990; 197–218. 40. Goldmann L, Shah MV, Hebden MW. Memory of cardiac anaesthesia. Psychological sequelae in cardiac patients of intra-operative suggestion and operating room conversation. Anaesthesia 1987; 42: 596–603.
CLINICAL INVESTIGATIONS
Conscious awareness during general anaesthesia: patients’ perceptions, emotions, cognition and reactions D. SCHWENDER, H. KUNZE-KRONAWITTER, P. DIETRICH, S. KLASING, H. FORST AND C. MADLER
Summary We interviewed 45 patients, who answered advertisements (n : 21) or were referred by colleagues (n : 24), about their experience of intraoperative awareness using a standardized questionnaire. Auditory perceptions, hearing sounds or voices were mentioned by all patients (45 of 45): 33 of 45 patients understood and recalled conversations; 21 of 45 patients had visual perceptions; 12 of 21 recognized things or faces; 29 of 45 patients felt being touched; three patients had the sensation of moderate pain; and eight patients were in severe pain. Patients’ feelings were mostly related to paralysis (27 of 45), helplessness (28 of 45), anxiety and fear (22 of 45); 18 were in severe panic. All patients (45 of 45) recognized the situation as a real event: 22 of 45 patients experienced unpleasant after effects; 11 suffered from anxiety and nightmares; and three developed post-traumatic stress disorder syndrome and required medical treatment. Twenty of 45 patients were especially attentive to emotionally relevant remarks on their own person, their disease and the course of their operation. The accuracy of sensory perception indicates a very high level of cognitive performance of patients during intraoperative awareness. (Br. J. Anaesth. 1998; 80: 133–139) Keywords: anaesthesia, general; memory; psychological responses
anaesthesia,
depth;
The incidence of awareness during general anaesthesia that can be recalled explicitly after operation has been reported to be 0.5–2%.1–9 Patients waking up during their anaesthetic are awake, in agony, intensely fearful but completely helpless, thinking that something must have gone terribly wrong. After operation, they recall all of the details of the procedure and the shock of this experience may cause post-traumatic stress disorder (PTSD).9–11 Characteristic symptoms of PTSD involve reexperiencing the event, sleep disturbances with recurrent nightmares, avoidance of stimuli associated with the event, numbing of general responsiveness or increased arousal, anxiety and preoccupation with death, that in some cases require long-term medical and psychological support or treatment.9 12 Information on what patients perceive and recall of events during general anaesthesia is based mostly on case reports.13–21 Most of these case reports relate to
the patient’s actual experience rather than patient reactions or after effects of awareness. Consequences of intraoperative awareness have been described only on the basis of small series of patients.22–29 Only two studies analysed patients’ feelings during, and patients’ reactions to, awareness. Evans studied 27 patients with recall after anaesthesia having selected his patients by advertising in four British newspapers.30 Bias of this sample cannot be excluded because advertisements select a disproportionate number of patients with a strong interest in their own medical history (so-called complainers). Therefore, Moerman, Bonke and Oosting investigated 26 patients with experiences of awareness during anaesthesia referred by colleagues of the anaesthesia department of a large university hospital.31 In this study we have investigated two groups of patients with experiences of awareness. One group was collected from advertisements in four German newspapers and the Internet. Patients in the second group were referred by colleagues of the anaesthesia departments of one large university hospital and two large community hospitals. The incidence, quality, intensity and accuracy of sensory perceptions, emotions and feelings, cognition and realization, reactions, consequences and after effects during and after intraoperative awareness was assessed within and between groups.
Patients and methods After obtaining approval from the local Ethics Committee, two groups of patients with experience of awareness during general anaesthesia were collected. In group 1, patients answered advertisements placed in four German newspapers and on the Internet. The text of the advertisement was as follows: “For scientific research and documentation on the subject of ‘awake during general anaesthesia?’ the Department of Anaesthesia of Munich University and the Science Department of the German state television, section SDR, are looking for patients who woke up D. SCHWENDER*, MD, H. KUNZE-KRONAWITTER, MD, P. DIETRICH, MD, S. KLASING, Institute for Anaesthesiology, University of Munich, FRG. H. FORST, MD, Institute for Anaesthesiology, Klinikum Augsburg, FRG. C. MADLER, MD, Institute for Anaesthesiology, Klinikum Kaiserslautern, FRG. Accepted for publication: September 22, 1997. *Address for correspondence: Institute for Anaesthesiology, Ludwig-Maximilians-University, Munich, Klinikum Innenstadt, Nubaumstrae 20, 80336 München, Germany.
British Journal of Anaesthesia 1998; 80: 133–139
Time interval
12 yr
20 yr
2 yr
21 yr
4 yr 26 yr
30 yr
7 yr
4 yr
17 yr
2 yr
2 yr
19 yr
2 yr
5 yr
4 yr
20 yr 9 yr
16 yr
5 yr
2
3
4
5
6 7
8
9
10
11
12
13
14
15
16
17
18 19
20
21
Group 1 1 13 yr
Patient No.
M, 55 yr, 174 cm, 75 kg
F, 46 yr, 168 cm, 70 kg
F, 44 yr, 164 cm, 77 kg M, 49 yr, 176 cm, 77 kg
F, 33 yr, 171 cm, 86 kg
F, 55 yr, 159 cm, 59 kg
F, 33 yr, 155 cm, 82 kg
M, 56 yr, 179 cm, 80 kg
F, 46 yr, 161 cm, 95 kg
M, 55 yr, 198 cm, 90 kg
F, 23 yr, 163 cm, 47 kg
F, 58 yr, 168 cm, 73 kg
F, 45 yr, 163 cm, 63 kg
F, 40 yr, 167 cm, 65 kg
M, 47 yr, 176 cm, 140 kg F, 63 yr, 158 cm, 65 kg
F, 63 yr, 163 cm, 55 kg
F, 24 yr, 162 cm, 60 kg
M, 63 yr, 169 cm, 84 kg
M, 26 yr, 194 cm, 85 kg
F, 31 yr, 160 cm, 80 kg
Patients’ data (sex, age, height, weight)
Aortocoronary bypass
Caesarean section (emergency)
Abortion curettage Aortocoronary bypass (emergency)
Caesarean section (emergency)
Multiple trauma (emergency)
Caesarean section (emergency)
Anal fissure
Operation of the cervical spinal column
Parotid tumour
Herniorrhaphy
Lower extremity fracture
Cardiac valve replacement
Operation on external ear
Arthroscopy knee Caesarean section
Nephrostomy
Cholecystectomy
Total hip replacement
Operation of a funnel breast
Dental surgery
Operation
Table 1 Case reports, patient data, perceptions, feelings and sequelae
Heard people talking: “Stop, she is waking up, she needs some more anaesthetic”, saw silhouettes, no pain, no anxiety Felt hands and arms during being positioned and heard voices say: “we won’t get along this way, we have to lay him down” Heard voices and the sound of metal, saw silhouettes and felt that his leg was moved up and down, moderate pain, helpless, in panic, tried to alert someone Heard voices, felt no pain, helpless and in panic, paralysed, tried to open eyes and to alert someone Heard voices and the sound of metal, unable to open eyes, no pain, no anxiety Heard a voice saying: “how can a man be so fat” Felt skin incision and touch, unbearable pain, heard: “she moves, she is coughing”, saw silhouettes, felt paralysed, helpless, in panic, tried to alert someone Heard sounds and understood conversation, no pain, clear sight, tried to alert someone, felt paralysed Heard the sound of metal and a voice saying: “the patient tries to move. He is waking up!” tried to move finger, felt paralysed, unable to open eyes, tried to talk, felt helpless, no fear, no pain Heard voices, felt skin incision and unbearable pain, saw silhouettes, unable to move, helpless, tried to alert someone Moved arm and heard voice saying: “she is awake, she needs more anaesthetic” no anxiety, no pain Heard voices talking about the patient’s increase in blood pressure, no anxiety, no panic, no pain Recalled conversation concerning her overweight: “how can a women be so fat?” and other disgusting jokes about her body weight Heard voices and understood conversation about how he lay on the operation table Heard: “She is awake” saw silhouttes, unable to open eyes, felt unbearable pain, paralysed, helpless, in panic, tried to alert someone Heard voices and conversation of medical staff, saw light, silhouettes, no pain Felt pain during skin incision, heard conversation: “What about the suction device?” Tried to move, felt paralysed, saw lights and silhouettes Heard sounds, saw light, no pain, felt paralysed, helpless, in panic Heard and recalled conversation during emergency defibrillation, felt the electrical shocks and heard a voice saying: “We won’t get him”, panic Heard sounds and conversation, able to understand and recall conversation, no pain, heard the sound of the crying baby after delivery Heard sounds, understood conversation, no pain, felt paralysed
Perceptions during intraoperative awareness
Anxiety, depression unable to stay in his job as an electrician, post-traumatic stress disorder
None
None Severe anxiety, post-traumatic stress disorder, psychotherapy
Nightmares and sleep disturbances for 2 yr
Nightmares, increased fear for future anaesthetics and operations None
None
Depression for several weeks
Nightmares, could not stay in bed after waking up None
None
Nightmares, anxiety of being unable to open eyes, for instance, when driving a car
None
None Increased fear for future anaesthetics and operations
None
None
Exaggerated sensitivity to sounds for 1.5 yr
None
None
Sequelae
134 British Journal of Anaesthesia
Time interval
5 yr
16 yr
4 yr
5 yr 1 yr
20 yr
7 yr
10 yr
6 month
1 yr
10 yr
1 yr
21 yr
1 yr 8 yr
6 yr
8 yr 6 yr 10 yr
11 yr
2 month 4 month 4 month
2
3
4
5 6
7
8
9
10
11
12
13
14
15 16
17
18 19 20
21
22 23 24
Group 2 1 2 yr
Patient No.
F, 37 yr, 165 cm, 72 kg F, 43 yr, 162 cm, 62 kg M, 64 yr, 172 cm, 68 kg
F, 38 yr, 172 cm, 80 kg
M, 50 yr, 181 cm, 80 kg F, 29 yr, 168 cm, 72 kg F, 25 yr, 165 cm, 59 kg
F, 34 yr, 165 cm, 79 kg
M, 14 yr, 161 cm, 54 kg F, 34 yr, 175 cm, 68 kg
F, 30 yr, 172 cm, 58 kg
M, 43 yr, 180 cm, 86 kg
F, 60 yr, 174 cm, 93 kg
F, 46 yr, 166 cm, 80 kg
M, 44 yr, 182 cm, 85 kg
M, 24 yr, 170 cm, 80 kg
F, 39 yr, 159 cm, 74 kg
M, 45 yr, 179 cm, 74 kg
F, 36 yr, 162 cm, 63 kg F, 34 yr, 170 cm, 70 kg
M, 35 yr, 180 cm, 80 kg
F, 37 yr, 167 cm, 42 kg
F, 33 yr, 169 cm, 52 kg, (anaesthetist)
F, 52 yr, 168 cm, 73 kg, (anaesthetist)
Patients data (sex, age, height, weight)
Laparoscopic cholecystectomy Laparoscopy Cholecystectomy
Appendicectomy (emergency)
Aortocoronary bypass Caesarean section (emergency) Dental surgery
Appendicectomy
Gastroscopy Caesarean section (emergency)
Tonsillectomy
Dental surgery
Laparatomy, peritonitis (emergency)
Meniscectomy
Appendicectomy (emergency)
Upper extremity fracture
Caesarean section (emergency)
Septorhinoplasty
Multiple trauma, laparatomy (emergency) Laparoscopic cholecystectomy Thyroidectomy
Appendicectomy (emergency)
Excisional biopsy, breast tumour
Abdominal hysterectomy, anaphylactic shock (emergency)
Operation
Table 1 Case reports, patient data, perceptions, feelings and sequelae—continued
British Journal of Anaesthesia 1998; 80: 133–139
None
None None
Increased fear of future operations or anaesthetics Fear to die
None
None
Sequelae
Sleep disturbances, fear to die, post-traumatic stress disorder, psychotherapy Felt intratracheal tube, heard voices and conversation: “Now we can None start with the operation”, tried to open eyes, felt paralysed, no pain Heard voices, felt painful skin incision, paralysed, helpless, tried to None alert someone Heard conversation: “We now take a photo and show it to her None afterwards”, felt hands touching her, helpless, paralysed, panic Heard surgeons saying: “Why do we always have to treat the Anxiety, nightmares complications of other medical centres? This woman is lost anyhow.” Heard the surgeon saying something to the anaesthetist, saw the None surgical gloves as a silhouette Felt her mouth being opened, could understand conversation and None recognised the surgeon, the medical staff and the operating theatre. Moderate pain Heard conversation, felt touch, felt suffocated and paralysed None Felt being touched, tried to alert someone, felt paralysed, heard None voices Heard the surgeon saying: “She needs some more anaesthetic, None because she is a red haired nurse and everything is different and very special in her case.” Heard voices, saw lights and silhouettes None Felt being touched, heard the sound of the crying baby None Opened eyes, saw the surgeon, who went to call for the anaesthetist, None saying: “She needs some more anaesthetics.” Felt the tracheal tube and heard the surgeon saying: “The appendix None is shortly before perforating.” Felt the tracheal tube, felt helpless, anxious None Heard the voice of the anaesthetist, unable to open eyes None Felt tracheal tube, heard voices None
Heard the word: “You have to give epinephrine, realized the emergency situation, thinking this is no more routine management, guys you are in severe difficulties, but I am sure, that you are doing the right things, giving epinephrine”, no anxiety, no pain High-dose fentanyl anaesthesia, awake during the whole surgical procedure, heard sounds and conversation, saw silhouettes and felt being touched during the operation, no pain, no anxiety Heard sounds and voices: “Can we start with the operation now?” Tried to alert someone, felt paralysed, helpless, in panic, no pain, Heard voices, saw silhouettes, no pain, felt helpless and paralysed, in panic, thought: “Now I have to die”, tried to alert someone Painful feeling in the upper abdomen, tried to move, felt paralysed Heard voices saying: “the tube is too big but, we do not have another”, no pain Heard sounds, opened eyes, saw surgeon and light, felt pressure on his head, no pain Felt warm fluid flowing over her abdomen, tried to open eyes, fear of bleeding to death
Perceptions during intraoperative awareness
Awareness during general anaesthesia 135
136 during surgery while the operation was going on. Your experience will be an important contribution to our work. Please contact us. Your replies will be regarded as confidential. Please reply to SDR, ScienceDepartment 68028 Mannheim/Germany.” Patients in group 2 were referred by colleagues of the anaesthesia departments of a large university hospital (Institute for Anaesthesiology, LudwigMaximilians-University Munich, Klinikum Innenstadt) and two large community hospitals (Institute for Anaesthesiology, Klinikum Augsburg and Institute for Anaesthesiology, Klinikum Kaiserslautern) requesting that they refer all patients with experience of awareness regardless of when the experience had occurred or the anaesthesia had taken place. All patients in the two groups were interviewed using our standardized questionnaire “Awareness during general anaesthesia”. The questionnaire was subdivided into six sections: personal data, detailed description in own words, sensory perceptions, feelings and emotions, cognition and interpretations, reactions, consequences and after effects. The following data were collected. (1) Personal data: patient’s name and address, age, sex, height, body weight, date, place and type of surgery, and preoperative feelings of nervousness, anxiety and pain. (2) In the second section, patients were allowed to give a detailed description in their own words of perceptions, feelings and thinking while being awake during the anaesthetic. (3) Incidence, quality, intensity and accuracy of sensory perceptions within the different sense modalities. Auditory modality: loud, low, close, far away, identification of the direction of the sound source, recognition of sounds or voices, understanding of language and conversation. Visual modality: able to describe light, shades, silhouettes, clearly or everything looking hazy, able to recognize things or people, either isolated or within a visual context. Tactile modality: feeling of being touched, quality and localization of sensation. Paralysis: unable to move arms, legs, head, vocal cords or other sites. Nociceptive modality: feeling pain, intensity, ranging from none, moderate to severe (0, 1, 2), identification of painful body part. (4) Feelings and emotions differentiated into helplessness, weakness, fear and panic, with intensity ranging from none, moderate to severe (0, 1, 2). (5) Interpretation of the situation and cognition, interpretation as dream or reality, estimation of duration and whether patient is trying to alert anyone or make signs. (6) Patients’ reactions, consequences for daily life and after effects: anxiety, fears, nightmares with intensity ranging from none, moderate to severe (0, 1, 2). Other consequences for daily life such as re-experiencing the event, numbing of general responsiveness, increased arousal, loneliness and lack of confidence in future life. Changing of opinion on anaesthesia and surgery and fear of repetition or more fear of future anaesthetics or surgeries. Duration of symptoms and whether the symptoms required medical treatment or a PTSD syndrome developed.
British Journal of Anaesthesia The last question was whether the patient informed the anaesthetist, surgeon, ward staff, general practitioner, partner, family or friends and what was their reaction. STATISTICAL ANALYSES
Data are presented as mean (SD). For differences between groups, groups were compared using the Mann–Whitney U or chi-square test. Subgroups of patients were compared using chi-square or Fisher’s exact test (two-sided). Differences were considered significant if P : 0.05, after Bonferroni’s correction for multiple comparisons.
Results During an 8-month period, 45 patients were analysed; 21 patients replied to the advertisements (group 1) and 24 patients were referred from the three hospitals involved in the study (group 2). In total, 45 questionnaires of awareness during general anaesthesia were analysed. In table 1, case reports, patient data, a short description of patients’ perceptions and feelings, and postoperative sequelae are presented. The two groups were comparable in patient data, type of surgery, a wide range of incidence, quality, intensity and accuracy of perceptions, emotions, cognition, reactions and after effects. Details on patients (sex, age, weight, height, time interval between interview and anaesthesia), type of surgery, patients’ descriptions of their experiences of awareness in keywords and postoperative sequelae are presented in table 1. Mean age of the patients was 41.7 (range 14–64) yr, mean body weight was 73.9 (47–140) kg and body height 169.75 (153–194) cm. Thirty patients were female and 15 male, and the time interval between the event and the interview was 9.6 yr (range 0.1–30 yr). Events occurred during anaesthesia for elective general abdominal (n:16), cardiothoracic (n:5), orthopaedic (n:6), gynaecological (n:4) or ear–nose–throat or dental surgery (n:7). Seven cases of awareness were observed during Caesarean section and 14 patients underwent emergency surgical procedures. In table 2 the incidence, quality, intensity and accuracy of perceptions, emotions, cognition, reactions and after effects are presented for group 1, group 2 and for both groups combined. SENSORY PERCEPTIONS WITHIN THE DIFFERENT SENSE MODALITIES
All patients (45 of 45) had auditory perceptions, hearing sounds or voices. The sound source was described as loud in 28 of 45 and close in 29 of 45 patients; 33 of 45 patients understood and recalled conversations. Patients in group 1 heard the sounds louder and closer when being aware and were significantly more often able to understand conversations; 21 of 45 had visual perceptions, and 10 of these 21 described their vision as clear, while 10 patients saw only silhouettes. Twelve patients recognized things or faces and 10 were able to localize this in the visual context of the operating room. Twenty-nine patients felt being touched, 28 of these were able to localize exactly where they felt the touch. Thirty-four
Awareness during general anaesthesia patients felt no pain, three patients felt moderate and eight patients severe pain. All patients with pain perceptions were able to localize exactly were they felt the pain. Twenty-seven patients had the feeling of paralysis, 22 of whom were able to localize the paralysed body parts. EMOTIONS
Twenty-eight of 45 patients felt helpless, 22 of 45 had feelings of anxiety and fear, four had moderate fear and 18 were in severe panic. COGNITION
All patients (45 of 45) recognized their situation as a real event. The estimated duration of the awareness episode during anaesthesia ranged from 1 to 60 min (mean duration 7.73 min). Thirty-one of 45 patients tried to alert someone or to make signs.
137 nightmares more often and after effects lasted significantly longer compared with those in group 2. Forty of 45 patients informed the anaesthetist, surgeon, medical staff, family or friends after operation. The response appeared to be affirmative, ranging from sympathy and explanation (19 of 40), or defensive, ranging from disbelieve to denial (10 of 40). We subdivided all patients into two groups and compared those patients with and without after effects. Almost all patients with after effects had changed their opinion on anaesthesia and surgery (P : 0.001). Patients with after effects were significantly more often helpless (P : 0.001) and in fear or severe panic (P : 0.049) when being aware during operation compared with patients without after effects. There was no difference between patients with and without after effects regarding incidence and intensity of pain perception (P : 0.856) and other sensory perceptions, emotions and cognition.
Discussion REACTIONS AND AFTER EFFECTS
Twenty-two of 45 patients suffered from after effects of their awareness episode; 21 changed their opinion on future anaesthetics and operations, 11 suffered from anxiety during the day and 11 suffered from nightmares. In nine patients the awareness episode had consequences for their daily life, three required medical treatment and three patients developed PTSD syndrome. The mean duration of after effects was 0.84 (range 0.1–5.0) yr. Patients in group 1 had
The two patient groups (21 patients who answered the advertisement (group 1) and 24 patients referred by colleagues of the large hospitals (group 2)) were comparable in patient data, type of surgery, a wide range of perceptions, emotions and cognition during their awareness episode, and incidence of after effects. Differences were found only in the quality of auditory perception and the incidence of understanding of language. Patients in group 1 heard the sounds louder and closer and were significantly more
Table 2 Incidence, quality, intensity and accuracy of perceptions, emotions, cognition, reactions and after effects. *P:0.05; **P:0.01 (chi-square test)
Auditory perception Intensity loud** Distance close* Understanding language, recall conversation* Visual perception Quality of visual perception clear Recognition of things, faces within a visual context Tactile perception localisation of tactile perception Pain perception moderate Pain perception severe localisation of pain Paralysis localisation of paralysis Helplessness Anxiety moderate Anxiety severe panic Recognition as real event estimated duration of awareness (min) (mean (SD)) Tried to alert someone After effects Duration of after effects** (yr) (mean (SD)) Changed opinion Anxiety Nightmares** Consequences for daily life Medical treatment Post-traumatic stress disorder Informed other people Anaesthetist Surgeon Ward staff General practitioner Family/friends Response of other people affirmative (sympathy to explanation) Response of other people defensive (disbelief to denial) Response of other people no detail
Group 1 n (%)
Group 2 n (%)
Group 1;2 n (%)
21 (100.0) 17 (80.9) 18 (85.7) 18 (85.7) 11 (52.4) 5 (45.5) 6 (54.5) 4 (36.4) 14 (66.7) 13 (92.9) 1 (4.8) 6 (28.6) 7 (100.0) 13 (61.9) 11 (84.6) 13 (61.9) 1 (4.8) 10 (47.6) 21 (100.0) 9.46 (6.08) 16 (76.2) 11 (52.4) 1.59 (1.93) 10 (83.3) 6 (66.7) 8 (80.0) 7 (63.6) 2 (18.2) 2 (18.2) 19 (90.5) 10 (52.6) 12 (63.2) 7 (36.8) 4 (21.1) 14 (77.8) 8 (42.1) 5 (26.3) 6 (31.6)
24 (100.0) 11 (45.8) 11 (45.8) 15 (62.5) 10 (41.7) 5 (50.0) 6 (60.0) 6 (60.0) 15 (62.5) 15 (100.0) 2 (8.3) 2 (8.3) 4 (100.0) 14 (58.3) 11 (78.6) 15 (62.5) 3 (12.5) 8 (33.3) 24 (100.0) 6.00 (13.1) 15 (62.5) 11 (45.8) 0.08 (0.15) 11 (100.0) 5 (45.5) 3 (27.3) 2 (18.2) 1 (10.0) 1 (10.0) 21 (87.5) 13 (61.9) 7 (33.3) 5 (23.8) 2 (10.5) 9 (45.0) 11 (52.4) 5 (23.8) 5 (23.8)
45 (100.0) 28 (62.2) 29 (64.4) 33 (73.3) 21 (46.7) 10 (47.6) 12 (57.1) 10 (47.6) 29 (64.4) 28 (96.6) 3 (6.7) 8 (17.8) 11 (100.0) 27 (60.0) 22 (81.5) 28 (62.2) 4 (8.9) 18 (40.0) 45 (100.0) 7.32 (14.17) 31 (68.9) 22 (48.9) 21 (91.3) 11 (55.0) 11 (52.4) 9 (40.9) 3 (14.3) 3 (14.3) 40 (88.9) 23 (57.5) 19 (47.5) 12 (30.0) 6 (15.8) 23 (60.5) 19 (47.5) 10 (25.0) 11 (27.5)
138 often able to understand conversations. One important difference between groups was that group 1 patients had nightmares more often and after effects lasted significantly longer than in group 2 (mean duration 1.59 vs 0.08 yr). This may be because of a bias in patient collection, indicating that patients who answered the advertisements had severer and longer lasting postoperative sequelae and possibly a stronger interest in their own medical history (so-called complainers). Our data support the suggestion of Moerman, Bonke and Oosting that it cannot be excluded completely that by advertising, a patient sample is biased and a disproportionate number of “complainers” may be selected with a strong personal interest in their own medical history.31 As in the studies of Moerman, Bonke and Oosting31 and Evans,30 reports of awareness during anaesthesia in our analyses occurred not only during “high risk awareness” surgical procedures such as obstetric, cardiac or emergency surgery. The majority of awareness cases in our study occurred during elective ear, nose, throat, dental, general, abdominal, orthopaedic or gynaecological surgery, indicating that awareness during anaesthesia is not only a problem of special surgical procedures but may occur occasionally during anaesthesia for almost any elective procedure. The incidence of perceptions within the different modalities during intraoperative awareness correspond well with data reported in the literature.1 9 15 24 26 27 30 32 All patients were able to hear, indicating that the auditory modality is the most important sensory channel during intraoperative awareness. A high percentage of patients, especially those who heard loud sounds with the sound source close by, were able to understand language and remember conversations after operation. Twenty patients were especially attentive to emotionally relevant remarks, that is they recalled remarks on their own person, disease and course of the operation (two cases of derogatory remarks, two cases of very meaningful remarks and 15 cases of some type of meaningful remarks). This finding may support a widespread belief that meaningful words and remarks are recalled more easily than neutral sounds and have a greater impact on the patient.25 28 29 32–36 On the other hand, 25 patients recalled only general theatre chat and noise. Visual perception was reported by nearly 50% of our patients. This experience has been rarely documented and exceeds incidences reported by Moerman, Bonke and Oosting (27%) and Evans (33%). Furthermore, 50% of our patients with intraoperative visual perceptions had clear sight and could recognize things and faces within a clear visual context of their visual field. A high percentage of patients had tactile sensations and almost all were able to localize the body parts exactly where they were being touched. The high incidence of paralysis in our study corresponds well with data from the literature and in almost all cases the paralysed body parts could be identified. The incidence of pain perception in our study (25%) was less than that reported in the literature (40%).30 31 Nevertheless, 17.8% of patients had severe pain. All patients were able to localize the body part exactly where the painful stimuli occurred.
British Journal of Anaesthesia Jones estimated the incidence of conscious awareness with pain to be lower than 1 in 3000 anaesthetics, and the incidence of conscious awareness without pain perception to be 1–3 in 300 anaesthetics.9 This would imply that painful feelings occur in less than 10% of patients who are aware during anaesthesia. Our data and those of Moerman, Bonke and Oosting, and Evans exceed this estimate; this may be a result of the small sample size and the possible disproportionate number of “complainers” in our study. Two-thirds of patients had emotional distress during their intraoperative awareness and felt helpless or anxious; 40% felt severe distress and panic, an incidence significantly lower than that reported by Moerman, Bonke and Oosting (92%)31 and Evans (78%).30 The percentage of patients who suffered after effects (50%) was slightly lower than in the study of Moerman, Bonke and Oosting.31 Their symptoms corresponded with those reported in the literature.9–12 22 28 37–40 Anxiety during the day, nightmares and sleep disturbances with consequences for daily life were most frequently mentioned. Most often, patients with after effects changed their opinion on anaesthesia and surgery with more fear for future procedures and that such an episode could happen again. Three patients required medical treatment after operation because of the development of PTSD. Why some patients experience after effects or develop PTSD and others do not cannot be explained from the present data. In contrast with Moerman, Bonke and Oosting,31 we did not find a trend towards a correlation between intraoperative pain perception and the incidence of after effects in our patients. Nevertheless, our patients with after effects felt significantly more helpless, fearful or severe panic during operation than patients without after effects. The percentage of patients who informed an anaesthetist, surgeon, hospital staff, family or friends (89%) was higher in our study than reported previously.30 31 This may reflect the increasing popularity that the topic of awareness during anaesthesia has gained in the lay press within the past years and the growing general knowledge of such problems. In contrast with Moerman, Bonke and Oosting, and Evans, responses were mostly affirmative, ranging from sympathy to explanation of the event, although responses of disbelief and denial occurred in some cases. These observations may indicate a steadily increasing understanding of the phenomenon and problems of intraoperative awareness on the part of the patient in addition to anaesthetists and surgeons. In summary, our data indicated a high accuracy of sensory perceptions, especially auditory perceptions, understanding and recall of conversations, and a high level of cognitive performance of patients during intraoperative awareness. The results illustrate the need for the anaesthetic and operating theatre staff to realize that awareness may be occurring during general anaesthesia.
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