15. Awareness Flashcards
You are called to see a patient on the surgical ward by the Sister because
a patient describes being aware during surgery (you did not anaesthetise
the patient).
How do you deal with the situation?
Inform the anaesthetist involved and the head of the department – there
may be a departmental policy or someone with a special interest in
awareness.
Interview the patient with a senior colleague – (Ideally the anaesthetist
involved should do this.) Always have a witness present.
Establish the events surrounding the time of alleged awareness by
reviewing the anaesthetic charts, discussing with the anaesthetist involved
and the patient.
Establish whether it is true recall or dreaming. Recall may be further divided
into explicit (patient can recall conversations which took place in theatre) or
implicit (behavioural changes post-operatively due to intra-operative
subconscious learning).
Establish whether the patient was in pain – this has implications for
long-term psychological sequelae such as nightmares and flashbacks.
If there was a clear lapse in the standard of anaesthetic care, then honesty
with an admission of fault and an apology is appropriate.
Document all conversations and assessments in the case notes.
Hospital management including the legal department may need to be
informed in order that the events can be documented for future reference
in case of legal action.
Offer counselling for the patient.
What do you tell the patient?
It is important to acknowledge the patient’s feelings and let them know you
believe what they are saying.
This helps with the well-recognised psychological sequelae following an episode of awareness.
These include anxiety, insomnia, nightmares, depression,
a morbid fear of hospitals and doctors and a preoccupation with death.
It is helpful to explain why awareness might have
occurred through no particular fault but instead because of the need to
minimise the doses of anaesthetic agents given. If there is clear fault on the
part of the anaesthetist, then it may still be wise to admit it.
Although this is an admission of negligence, some say it may help to reduce anxiety for future anaesthetics if there was a definite reason for the awareness.
In summary, a full explanation of the events and an apology are recommended
What is the legal situation regarding awareness?
An anaesthetist has a duty of care towards a patient. A patient who is going
to have a general anaesthetic expects to be asleep and unaware.
To decide whether there is a breach in the duty of care,
the Bolam test is applied.
In the 1950s Bolam’s leg was broken during a course of ECT.
Bolam’s expert witnesses claimed that the omission of a muscle relaxant was negligent.
The experts called by the hospital were of the opinion that muscle relaxants were
not essential. The judge ruled that:
‘A doctor is not guilty of negligence if acting in accordance with a
practice accepted as proper by a responsible body of medical opinion
even though a body of adverse opinion also exists amongst medical
men’.
An anaesthetist must therefore prove that the technique he used is one that is
considered to be reasonable by his peers.
This is done through review of the
anaesthetic records by expert witnesses.
If there is evidence of a shortfall in
the standard of anaesthetic care, then the anaesthetist is guilty of negligence.
If the awareness can be clearly linked to the poor anaesthetic technique
(‘causation’), then compensation is payable.
When is awareness most likely?
At induction and intubation.
On transfer from the anaesthetic room to theatre.
During procedures involving the use of muscle relaxants.
TIVA.
During procedures where low concentrations of volatile are used
deliberately, e.g. LSCS or hypotensive patient.
At emergence.
Awareness with explicit recall has a reported incidence of approximately 1/500
and is most common during obstetric GA (especially at intubation). Awareness
with pain is far less common.
What are the causes of awareness?
- Induction
Low doses of drugs as above
Intubation too early or delayed due to difficulty or waiting for relaxant to work - Transfer
Induction agent levels fall before adequate partial
pressure of volatile builds up - During surgery
Equipment failure, e.g. breathing system leak/
disconnection, vaporiser, malfunction or exhaustion,
TIVA line tissued
How do you monitor depth of anaesthesia?
- Simple clinical signs
BP, HR, sweating, lacrimation, pupils - MAC
Based on population studies
3.I solated forearm technique
- Spontaneous skeletal muscle activity
Frontalis, lost with relaxants - Oesophageal contractility
Depth of anaesthesia related to frequency of contractions - Evoked potentials
Visual, auditory, somatosensory (changes in latency and amplitude) - EEG
Spectral edge frequency Frequency when significant EEG activity is
seen - Cerebral function monitor
Processed EEG makes interpretation easier - Bispectral index
- Heart rate variability ‘Fathom’ monitor – loss of respiratory
sinus arrhythmia
Guedel Classification of the Stages of Anaesthesia:
- Analgesia
- Excitement
- Surgical Anaesthesia
Plane 1-4 - Coma
Guedel Classification of the Stages of Anaesthesia:
1
Stage 1
Analgesia
Start of induction to LOC
Regular, small volume respiration
Normal pupils
Guedel Classification of the Stages of Anaesthesia:
2.
Stage 2
Excitement
LOC to onset of automatic breathing
Irregular respiration
Dilated, divergent pupils
Active airway reflexes
Loss of eyelash reflex
Stage 3
- Surgical anaesthesia
Plane 1-4
Plane 1
Plane 1:
Regular, large volume respiration
Eye movements stop, pinpoint pupils
Loss of eyelid reflex
Plane 2
Intercostal respiration reduced
Loss of corneal reflex
Plane 3:
Diaphragmatic respiration
Laryngeal reflexes reduced
Normal pupils
Plane 4:
Diaphragmatic respiration reduced
Carinal reflex depressed
Dilated pupils
Stage 4
Coma Apnoea, hypotension
