MW is a member of the 5th National Audit Project (NAP5) on Accidental Awareness During General Anaesthesia Steering Panel. No external funding declared. Previously posted on the Anaesthesia correspondence website: www.anaesthesiacorrespondence.com.
Isolated forearm technique and consciousness
Version of Record online: 9 DEC 2013
© 2013 The Association of Anaesthetists of Great Britain and Ireland
Volume 69, Issue 1, pages 78–80, January 2014
How to Cite
Russell, F. and Wang, M. (2014), Isolated forearm technique and consciousness. Anaesthesia, 69: 78–80. doi: 10.1111/anae.12547
- Issue online: 9 DEC 2013
- Version of Record online: 9 DEC 2013
Pandit  questions the meaning and implication of a positive isolated forearm technique (IFT) response to command. When patients breathe spontaneously, a response to command is widely accepted as indicative of consciousness. A tourniquet is simply a means of allowing a paralysed patient to move. Why should movements to command be interpreted differently in these two situations?
From a neuropsychological perspective, the process can be broken down as follows:
- Perceive human voice/English language: signal detection; pattern analysis; phoneme identification;
- Recognise action verb ‘squeeze’ and object (‘hand’): semantic analysis;
- Recognise it is a command: syntax analysis;
- Recognise the command is meant for you: self versus other perception and conceptualisation;
- Decide to follow the command: understanding of external environment, command origin and that hand movement will be seen by others.
- Move dominant hand as requested.
Thus, a co-ordinated and voluntary motor response to command involves activation of complex neural pathways in the temporal, limbic and frontal lobes, and cerebral cortex, and includes at least a basic understanding of the external environment and origin of the verbal command. The concept of ‘voluntariness’ implies conscious intent and it seems perverse not to associate the above processes with consciousness.
We challenge Pandit's grounds for questioning whether a positive IFT response represents ‘consciousness’ as follows:
- “The response takes place in the context of neuro-active medication and therefore cannot be viewed as a ‘normal’ response to command as might occur in the context of lucid mental state.” The presence of neuro-active medication does not preclude consciousness or lucid mental state, even with no memory of events, e.g. excessive alcohol intake or midazolam sedation;
- “There is inconsistency with response to pain.” Three components of modern general anaesthesia are commonly described (hypnosis, analgesia, muscle relaxation); when using individual drugs to achieve these effects, there may be little correlation of the effects. It is quite possible to have analgesia in the absence of hypnosis, especially if regional anaesthesia is used;
- “Anaesthetic drug dose does not consistently correlate with, and therefore cannot predict, a positive IFT response.” In individual patients, anaesthetic drug dose is a poor predictor of both plasma concentration and depth of consciousness. The effect of drugs on consciousness is also confounded by surgical stimulation, and whether anaesthesia is lightening or deepening ;
- “IFT patients do not move spontaneously in response to surgery.” Spontaneous goal-directed movement is well reported [3-5] and indeed, in one study utilising a rather poorly conducted IFT, the technique was abandoned because of ‘purposeful movements of the arm’ . Good analgesia reduces the incidence of such spontaneous reflex/purposeful movements but such movements do occur and the competent anaesthetist should then verify whether the patient is conscious [7-10];
- “At the end of surgery, when waking up, patients who responded intra-operatively at a particular anaesthetic concentration did not respond until the anaesthetic concentration was much lower.” This is to be expected: during the non-stable wake-up/washout phase of anaesthesia, expired isoflurane concentration will always be lower than brain concentration; ‘depth of anaesthesia’ is a balance of drug concentration and surgical stimulus – at the end of surgery there is no surgical stimulus ;
- “Patients without neuromuscular blockade do not move spontaneously during surgery at anaesthetic depths equivalent to those when positive IFT responses occur in the presence of neuromuscular blockade.” We are unsure what this statement means as the MAC-awake of isoflurane is ∼0.3 MAC  and this compares with the MAC values of responding patients in Russell's study . In the example case , the spontaneously breathing 12-year-old girl with a caudal block responded at an age-adjusted MAC of 1.1 ;
- “It is logically unsound to confine statements about patients' conscious state to the positive motor responses to command; some comment is also required on their lack of response to stimuli like surgery.” Absence of response to surgery may be because there is effective analgesia. With conscious sedation, quite clearly lack of response does not preclude consciousness. Patients who have had awareness with recall after general anaesthesia, with or without pain, describe the desperate search of their body for something to move to draw attention to their plight . Thus we think it highly unlikely that patients who regain consciousness during general anaesthesia will simply lie there waiting until commanded to move!
We dispute Pandit's claim that the IFT fails Turing's  first test of spontaneous goal-directed behaviour: such behaviour is widely described [3-6]. Pandit also claims there are no documented descriptions of sophisticated IFT conversations with patients, asking them why they are not moving in response to surgery. Using differently phrased questions, we regularly ask responding patients whether they are comfortable or in pain [7, 8]. It would be difficult to ask patients why they are not moving, since the questions would need to be complex (e.g. if ‘x’ then do ‘y’) and we know from experience that if the statement/question is too long/complex, partly anaesthetised patients will lose track and not respond.
Pandit argues that since many patients respond to IFT commands [9, 10], in routine anaesthetic practice (without the IFT) there must be many patients in a similar responsive state, unknown to the anaesthetist, who do not have anaesthesia deepened, and yet in routine practice few have recall . However, these studies [9, 10] involved BIS-guided anaesthetics, resulting in very low anaesthetic concentrations that would never be used in ‘routine practice.’ We dispute the figure of 1:15 000 patients with recall  as this is based on patients' spontaneous reports. We know that many, if not most, patients with awareness will not report it spontaneously for reasons that have been described elsewhere .
Russell has described two patients who consciously chose to ignore the commands  and remembered making this choice. Both were enjoying their mental state, but they were clearly conscious with subsequent recall. If there is a subgroup of patients who are conscious but do not respond to command and have no subsequent recall, then these patients would have similar reasons for not moving spontaneously – they would make a conscious choice not to move. We see no reason to confuse the issue by describing some hypothetical state (dysanaesthesia) should patients be conscious and not responding.
Patients who are aware with full postoperative recall often report their intra-operative awareness of staff, their exact positions, activities and conversations, despite being paralysed and unable to indicate their predicament. This is hardly ‘disconnected consciousness’ or ‘dysanaesthesia’. In the absence of other unequivocal evidence, it is logical for us to conclude that patients with positive IFT responses are likely to be in the same state of environmental ‘awareness’ as patients who recall awareness.
In summary, we do not accept that a positive IFT response represents a third state of consciousness (‘dysanaesthesia’ or ‘disconnected consciousness’). Consciousness is relatively independent of anaesthetic drug dose, the presence of other neuro-active agents, experience of, and response to, pain stimuli, and postoperative explicit recall. It is therefore no surprise that the only accurate and valid measure of intra-operative cognitive state (the IFT) shares all these apparently inconsistent characteristics.
- 6Isolated forearm technique for detection of wakefulness during general anaesthesia. British Journal of Anaesthesia 1981; 53: 665P., .
- 14The psychological consequences of explicit and implicit memories of events during surgery. In Ghoneim M. (Ed.) Awareness during Anesthesia. Woburn, USA, Butterworth-Heinemann, 2001..
- 15Computing machinery and intelligence. Mind 1950; 236: 433–60..