Awareness Under General Anaesthesia Flashcards
You are the anaesthetist on-call for labour ward and are asked to anaesthetise a 34-year-old parturient for a category 1 Caesarean section for a foetal bradycardia, which is still present on arrival to theatre. The patient is otherwise well, has no allergies, is appropriately starved and has good mouth opening with a Mallampati score of 2. Her BMI is 24.
What is your plan for induction of anaesthesia?
- This is an emergency, and time is of the essence. The patient should be assessed quickly to facilitate a rapid transfer to theatre, focusing on comorbidities, previous anaesthetics and the airway. The discussion should include an explanation and consent for a general anaesthetic and the associated risks.
- Ensure availability of the difficult airway trolley, resus trolley and emergency drugs.
- Apply AAGBI monitoring, complete the WHO checklist and pre-medicate with sodium citrate.
- Use a specific obstetric general anaesthetic checklist.
- Ensure appropriate positioning of the patient and pre-oxygenate for 3 minutes, targeting ETO2 >85%. Continue to pre-oxygenate until the antiseptic skin preparation and surgical drapes have been applied and
the obstetrician is scrubbed and ready to operate. - Carry out a rapid sequence induction with cricoid pressure and
suction on and readily available. - The choice of drugs should reflect experience and local practice but follows the principle that the drugs should have a rapid onset and offset. Thiopentone and propofol are both commonly used, with suxamethonium as the muscle relaxant.
- Intubate and ventilate the patient with oxygen/air mix, nitrous oxide and sevoflurane.
The procedure is completed with no complications. Two hours later you are asked to review the patient due to her being “awake during the operation”. How do you proceed?
- Review the anaesthetic chart prior to seeing the patient.
- Respond promptly and sympathetically in the presence of a senior midwife and the anaesthetic consultant on labour ward. The discussion should include a frank apology to the patient as well as an
explanation. - Take a detailed history from the patient about what she recalls including specific feelings, words or actions. Ask specifically about
pain. - Offer counselling and a further discussion with consultant anaesthetist at the earliest given opportunity.
- The conversation should be carefully documented and co-signed by those present.
- The patient should be followed up in an anaesthetic clinic.
- This should be reported as a serious untoward event and should be
escalated according to local protocols.
What is the incidence of awareness in patients undergoing an obstetric procedure?
- 1:670 according to NAP 5.
How do you account for the increased incidence of accidental awareness under general anaesthesia (AAGA) in obstetric patients?
Patient factors:
* Female.
* Younger age group.
* Raised BMI.
* Higher risk of a difficult airway.
* Anxious patient.
Anaesthetic factors:
* Use of rapid sequence induction.
* Use of a muscle relaxant.
Surgical factors:
* Emergency surgery.
* Excessive anaesthesia may be hazardous to the foetus, which may lead to the anaesthetist giving too low a dose of anaesthetic drugs.
* Some obstetric operations are performed in actively bleeding patients, therefore too low a dose of anaesthetic agent may be given with the intent of avoiding haemodynamic instability.
Human factors:
* High stakes situation can be stressful and make drug errors more likely.
* Obstetric units are often staffed by junior anaesthetists out of hours, and relative inexperience may make drug errors more likely.
* Lack of familiarity of drugs used in obstetrics e.g. thiopentone.
What questions form the modified Brice questionnaire for assessing patients who may have experienced awareness under anaesthesia?
- What is the last thing you remember happening before you went to sleep?
- What is the first thing you remember on waking?
- Did you have any dreams while asleep?
- What was the worst thing about your operation?
- What was the next worst?
