Memory, Awareness and Intravenous Anesthetics


Authors

N

Incidence (%)

Sandin and Nordström [8]

1727

0.2

Miller et al. [9]

90

6.7

Nordstrom et al. [10]

1000

0.2

Errando et al. [11]

4001

1.1

Zhang et al. [12]

5228

0.36





Case Examples from the British and Irish National Audit Project TIVA Reports


NAP5 provided a unique opportunity to evaluate many cases of accidental awareness in some detail and specifically in the context of TIVA . The following is a selection of cases which provide important clues as to the psychological mechanisms underlying the patient’s subsequent psychological difficulties—or otherwise. An absence of sequelae is often as instructive as in those where profound trauma is reported.


Case 1


The TIVA dose was reduced to manage intraoperative hypotension in a critically ill patient. A depth of anaesthesia monitor (not employed) may have helped in this complex case with neuromuscular blockade. Fortunately, the patient understood the nature of the paralysis and therefore suffered no psychological sequelae.

The patient stated: “I woke up and had a lot of pain, wanted to ask for pain killers, but couldn’t speak nor move; I couldn’t move a hand. I heard voices talking about drugs, saw bright light through my [closed] eyelids, I was vaguely clear that it was during the operation, and that you are supposed to be paralysed when you have an anaesthetic”. So this patient was not very distressed and protected psychologically because she understood the role, effect and reversibility of muscle relaxants. On close questioning, she was not aware at all of the tracheal tube, nor of being ventilated.


Case 2


The TIVA dose was reduced to manage hypotension. The TIVA technique used was described as TCI but in fact was not: the target was expressed in “ml/hr”. The patient was obese, receiving numerous chronic pain drugs and therefore at risk of accidental awareness; nevertheless, there was no depth of anaesthesia monitoring.

The patient reported coming out of anaesthesia which resulted in a major complication. The patient reported a brief episode of severe pain and a sense of something going on around her. She did not report any memory of voices or specific intraoperative events.

The patient suffered flashbacks and post-traumatic stress disorder as a result of her awareness experience.


Case 3


The patient underwent a wisdom teeth extraction procedure. There appears to have been incomplete or ineffective reversal towards the end of the anaesthetic, and the patient continued to experience paralysis on emergence. No nerve stimulator was used to monitor neuromuscular blockade. There was poor preoperative communication with the patient and failure to shape patient expectations. The consultant anaesthetist left the operating theatre before the end of the procedure, and the TIVA was discontinued too soon, allowing the patient to experience awake paralysis.

The patient was left with the impression she had become conscious during her operation and that she had been “held down” by surgical staff. This was probably her attribution of the paralysis.

No post-operative psychological sequelae were reported.


Case 4


In this case, the muscle relaxant was given late so reversal and extubation were delayed.

The patient stated: “I felt very frightened, I couldn’t breathe, I felt I was going to die”.

Immediately on waking up from the anaesthetic, the patient spontaneously remarked “I knew I was in trouble and I wanted to tell you, but I couldn’t move”.

The following day, the patient, on being questioned specifically by the anaesthetist, was unable to recall any details of the event and apparently was dismissive of the event saying “It must have been just me”.

No post-operative psychological sequelae were reported.


Case 5


Remifentanil and propofol TIVA was used but programmed wrongly for each. Tiredness of the anaesthetist could have been a factor in the error.

The patient remembered waking up and feeling unable to move or communicate, but thought “I’ll come round soon”, so she didn’t feel overly distressed.

No post-operative psychological sequelae were reported.

These cases illustrate a number of key points:


  1. 1.


    The importance of the experience of conscious paralysis as the principal cause of post-operative psychological trauma

     

  2. 2.


    The role of misattribution and misunderstanding of neuromuscular blockade during this experience of conscious paralysis in mediating acute psychological trauma, which can be obviated if the patient already has an accurate understanding of the use and effects of muscle relaxants

     

  3. 3.


    The importance of human error giving rise to TIVA underdosing or infusion failure which goes undetected because of the presence of paralysis, preventing body movement to indicate the patient’s predicament

     


Management of Accidental Awareness


The National Audit Project reporting prevalence (1:15,000; [2]) is completely at odds with that indicated by prospective Brice interview studies (1:600; [14]), which underscores the fact that the vast majority of those who have intraoperative memories are unmotivated or reluctant to complain or inform anaesthetic or surgical staff of what they have experienced [15]. When a patient does report that they have unexpected intraoperative memories, they may be experiencing acute distress in the recovery area or on the receiving ward. Typically it is the nursing staff who are first made aware that there has been a problem. The anaesthetist responsible for the awareness incident may well also be traumatised themselves by the report from the nurses and understandably will feel reluctant to see the patient (they too require care and support). However, it is advisable for both medicolegal and psychological welfare reasons for the anaesthetist to meet with the patient as soon as possible. It is also advisable that they take another member of staff as a witness. The anaesthetist should take a compassionate and empathic approach, making it clear that they wish to hear and understand what the patient has experienced. They should avoid being defensive, and seek to establish the facts of what has happened and accept that the patient experience is very real, irrespective of any misunderstandings on the patient’s part. The anaesthetist should avoid jumping to conclusions about what has happened at this early stage. They should feel able to apologise without admitting liability, given that this is the official stance of the medical defence union in these circumstances. Sometimes there has been some confusion on the patient’s part when, for example, perioperative experiences have been mistaken as intraoperative. Such misunderstanding must be handled gently and with great care, seeking to explain what has happened sensitively. If the patient’s account clearly indicates an episode of AAGA has occurred, the anaesthetist may wish to consult the anaesthetic record, the theatre equipment and colleagues, in order to investigate what may have gone wrong, before making any definitive comment to the patient. However, it is important that at the earliest opportunity, some explanation is provided to the patient. Sometimes no explanation will be immediately apparent, in which case it is necessary to communicate this. It is crucial that the anaesthetist makes it clear to the patient at all times that they believe the patient’s account, that they regret this has happened and that they are as anxious as the patient to understand what has gone wrong (see Fig. 43.1).

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Fig. 43.1
NAP5 psychological support pathway

The patient should be followed up during the following two weeks via outpatient appointment or telephone interview. It is common for traumatised patients to experience nightmares and flashbacks of intraoperative events during this period; however, in many the frequency and intensity of these phenomena will decline, and they may not need any specific intervention. It is always helpful to provide contact details of a psychologist or psychiatrist who is experienced in the treatment of PTSD, whether or not this option is called upon. If there is no improvement in PTSD symptoms over the first two weeks, referral is recommended [7, 16].

Psychologists or psychiatrists receiving such a referral should offer exposure-based cognitive behavioural therapy (CBT) or eye movement desensitisation and reprocessing (EMDR, as recommended by NICE [17]). The key common feature of these techniques is the repeated and deliberate evocation of the most traumatic aspect of the experience to encourage habituation, emotional processing and resolution of the conditioned fear response, along with the development of more rational and adaptive cognitive understandings and thoughts about the experience.


Death Fear


Some of the NAP5 awareness patients reported that during their experience of conscious paralysis, they actually believed they had died on the operating theatre table: that what they were experiencing (immobility, darkness but still being able to hear) was actually what death is like and that they would be in this condition for the rest of eternity. This relates to a very primitive and basic fear of death that commonly arises in children aged 7–11 when they first become aware of their own mortality [18, 19]. Typically children at this age do not conceptualise the cessation of consciousness but imagine permanent oblivion in which consciousness is preserved in the absence of perception, sensation or agency: a kind of eternal darkness of the soul, of which they are understandably terrified. It is possible that this primitive death fear lies within many of us, despite the later development of more adult conceptualisations and accommodation with our own mortality. Moreover, anaesthetic drugs may tend to depress frontal brain structures first (including rational adult cognition) and in a partially anaesthetised state, older, more primitive structures of the midbrain particularly concerned with emotional processing may be left intact. This partially anaesthetised state may allow primitive childhood memory and emotional processing to re-emerge. This state may therefore provide fertile ground for the emergence of an underlying fearful conception of death, reinforced by darkness, and an inability to move, which gives rise to profound psychological trauma, even though this state proves to be temporary and reversible. This may account for the severity of psychological and emotional impact of accidental awareness and its devastating effects on post-operative quality of life in some patients.

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Jul 14, 2017 | Posted by in Uncategorized | Comments Off on Memory, Awareness and Intravenous Anesthetics

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