Theatre Anaesthetics

Question 1

What are the 4 different techniques of regional anaesthesia. Which is used most often? give 2 examples of that one.

Answer 1

Local aesthetic field block
Peripheral nerve block
Nerve Plexus block
Central neuraxial block e.g. spinal or epidural

Question 2

At what level does the spinal cord in adults end?
At what level does the spinal cord end in children?

Answer 2

Adults: L1/L2
Children: L3/L4

Question 3

At what vertebral level is epidural anaesthetic inserted? How about spinal anaesthetic?
At what level is the epidural anaesthetic inserted in labor

Answer 3

The epidural anaesthetic can technically be inserted anywhere along the spine as it does not affect the the spinal cord. In labor L3/L4
The spinal cord ends at L1/L2 in adults => Spinal anaesthetic must be inserted at L3/L4 or L4/L5 or lower.

Question 4

The components of general anaesthesia are sometimes called the ‘triad of anaesthesia’. What is this triad? Give examples of each

Answer 4

Hypnotic: Propofol, SEV (Sevoflurane)
Analgesic: Fentanyl, Oxynorm
Muscle relaxation: Depolarising (Suxamethonium)
Non-depolarising: Rocuronium

Question 5

Take me through when a patient arrives for surgery until induction

Answer 5

1) Patient starts int eh pre-operative area where they should be reviewed and assessed by the anaesthetist
2) They are then brought to the operating room/induction room (if present). There the WHO safe checklist will be completed, monitoring devices are applied and IV cannulation is established
3) Anaesthesia is administered (GA, RA, Sedation),
Extra: the patient is intubated (I-gel or LMA - laryngeal mask airway), analgesia snd/or muscle relaxants are administered.

Question 6

What are the 2 methods of induction. State the agent used in each and the indication for the use of each

Answer 6

IV: Propofol is the standard agent
Inhalation: Sevoflorane gas is used
Inhalational anaesthesia is only used in induction over IV in paediatric practice (don’t like it), cases of difficult airway, difficult venous access, or inhaled foreign body

Question 7

What are the 2 the two types of muscle relaxants used in aneaesthesia. Give the example that is most used in practice. For each example state whether it is slow or fast acting.

Answer 7

Muscle relaxation: Depolarising: Suxamethonium - Fast acting
Non-depolarising: Rocuronium

Question 8

What is the main risk when administering suxamethonium? How is it reversed?
Give some other SE of administering this drug.

Answer 8

Malignant hyperthermia
Dantrolene
Other: Hyperkalemia, anaphylaxis

Question 9

Briefly explain Rapid Sequence Induction including:
indications
Preparation
actual sequence

Answer 9

Indications:
Apnea or severe respiratory failure
MAIN: Patient not fasting/full stomach/at risk of aspiration e.g. Emergency, obstetric emergency, Hx of reflux
Patient with altered mental status - GCS <9 (8 or less) (TBI, OD, poison)
Airway anatomy
Preparation: Pre-oxygenation to withstand during apneic period, sniffing position (Ear Canal in line with sternum)
Sequence: Pressure is applied to the cricoid bone (to close oesophagus and prevent aspiration -40N) Propofol is given along with fentanyl followed by suxamethonium or Rocuronium
Intubation may then take place.

Question 10

What is the reversal agent of Rocuronium?

Answer 10

Sugammadex (only works on this and vecuronium)

Question 11

How can you confirm the correct placement of airway? what is the gold standard?

Answer 11

Visualising the passage through the cords
Listening for breath sounds bilaterally
GOLD STANDARD: Capnography. End-tidal CO2 over 5 ventilatory cycles (no need for specifics)

Question 12

How would you tell that a muscle relaxant is starting to wear off?

Answer 12

Deep cleft/depression on end-tidal CO2 waveform

Question 13

The I-gel is a 2nd generation Laryngeal mask airway and is not separate from the inflatable one. Where does it sit. What is another method of securing the airway?

Answer 13

Suprglottic devices
Other = endotracheal intubation. Note that the ET tube can be passed through some LMAs

Question 14

There is another hole on the top of the I-gel. What is it for

Answer 14

It is a gastric channel

Question 15

What is MAC?

Answer 15

MAC or minimal alveolar concentration, is the alveolar concentration of a volatile agent which when given alone, prevents movement in 50%. Note that this is when given alone. When giving other agents such as propofol, it will also prevent movement.

Question 16

Give one hypnotic other than propofol

Answer 16

Thiopentone (must know this one)
Etomidate

Question 17

What are the systemic effects of general anaesthesia?

Answer 17

They are all respiratory depressants and depress airway reflexes
Vasodilation => reduced BP
Negative isotropy and chronotropy (reduced contractility and HR)

Question 18

What anti-emetics are used in anaesthesiology?

Answer 18

Ondansetron
Dexamethasone - Steroid, anti-emetic, and potentiated regional anaesthesia.

Question 19

What must be completed before emergence?
When is extubation performed?

Answer 19

Before emergence, stop delivery of hypnotic (SEV) and administer adequate analgesics (oxynorm) and anti-emetics (ondansetron). Lastly, ensure that neuromuscular junction function has been restored if a muscle relaxant was used

Extubation is performed following:
Suction of oropharynx
Patient is spontaneously generating good tidal volumes
Patient is awake and is able to protect own airways

Question 20

What is the triad of Malignant hyperthermia?

Answer 20

Hypercapnia, hyperthermia, leadpipe muscle rigidity.

Question 21

State all the steps involved in preoperative assessment (7)

Answer 21

Full medical history
Physical examination
Investigation
Risk assessment
Consultation with other medical specialties (if required)
Optimisation
Premedication

Question 22

What will you ask in the full history of the patient in pre-op assessment? Say as much as you can. Everything is included in the answer. 5/5 if you state all the major points not the specifics unless important

Answer 22

1) History of surgical problems (previous airway surgeries, joint surgery - for positioning problems, surgery problems)
2) Medical history:
Cardio: Sx of angina or CHF (SOB, orthopnea), HTN, pacemaker or ICD, exercise tolerance
Resp: Asthma, recent URTI, COPD…
Neuromuscular: Hx of TIA, stroke, seizure, sx of raised ICP, myasthenia gravis, myopathies
Endocrine: Diabetes, thyroid
Renal: Renal failure, dialysis dependency
GIT: GORD, Cirrhosis
3) Medications and Allergies
4) Previous anaesthesia history (difficult airway management, drug reaction, difficult epidural, post-dural puncture headache, post-op nausea/vomiting)
5) Family History related to anaesthesia e.g. malignant hyperthermia, sickle cell disease or cardiology
6) Social History (pre-issue exercise, smoking, alcohol, substance abuse)
7) Fasting hours (last oral intake)

Question 23

What classification is used in Cirrhosis?

Answer 23

Child-pew classification of cirrhosis

Question 24

MOA of ACE inhibitors
Give 2 examples of ACE inhibitors

Answer 24

Inhibits Angiotensin converting enzyme which is responsible for converting Ag1 into Ag2 which then acts to vasoconstrict (in which the drug will cause vasodilation => reduced BP)
Enalapril
Lisinopril
Ramipril

Question 25

What are ARBs? give MOA
Give 2 examples

Answer 25

Angiotensin receptor blockers. These block the effect of Ag2 on its receptors => vasodilation and reduced BP
Examples: -sartan
Losartan
Valsartan

Question 26

When conducting the pre-operative assessment, certain medications are specifically looked out for. What are these medications that should be stopped before surgery. If known, state the how long before they need to be stopped. (4 needed for 5/5)

Answer 26

1) All hypertensive medications should be continued until the morning of surgery except ACE inhibitors (enalapril) and ARBs (Losartan) (should be stopped earlier)
2) Diuretics should be stopped except in CHF (need it)
3) Oral contraceptives should be stopped 4 weeks prior
4) Warfarin should be stopped 5 days prior and clopidogrel 7 days prior. Note with these the decision should take into account underlying disease => consult
^^ these 4 are essential
5) Orał hypoglycemics should be stopped before surgery
6) MAOI (antidepressant not rly used) can interact with some meds

Question 27

What are the components of the CHADS score? Evaluate the different possible scores (low, med, high risk)
What is this score typically for?
what is this score used for in anaesthesiology?

Answer 27

Congestive heart failure (CCF), Hypertension (Systolic >140 persistently), Age >75, Diabetes, History of previous stroke or TIA (2 points)
1-2 = low, 3-4 = moderate, 5-6 = high risk
Score is typically to assess risk of stroke in patients with A.fib
In anaesthesiology it is to assess the risk of a thromboembolic event occurring preoperatively as well as tailoring peri-operative management to minimise the risk.

Question 28

What is a common side effect of lumbar puncture or spinal anaesthesia other than bleeding, infection, bruising at site or altered sensation.

Answer 28

Post-dural/puncture headache

Question 29

Why are patients asked to fast?
What manoeuvre may need to be performed in the case of inability to fast?
What is the 8,6,4,2 rule of fasting?

Answer 29

They are asked to fast to decrease the risk of aspiration during anaesthesia, otherwise the Rapid sequence induction manoeuvre may be necessary

8 hours after a meal that includes meat, fried, or fatty foods
6 hours after a light meal, infant formula, or non-human milk
4 hours after ingestion of breast milk
2 hours after clear fluids

Question 30

What would you perform as part of your anaesthesiology pre-op assessment?

Answer 30

CV exam with vitals and auscultation for murmurs
Resp exam with shape of chest, percussion and auscultation
Neurological: GCS + motor or sensory deficits
Airway: Detailed exam of airway for any congenital anomalies, loose teeth, dentures, Mallampati score (crowding), Thyromental distance, mouth opening and confirm with previous records for hx of airway difficulty
Spine: Exam of spine for neuraxial block if needed

Question 31

How do you assess the patient’s fitness for surgery?
Give the scoring system

Answer 31

ASA physical status classification (American society of anaesthesiologists)
ASA 1 = healthy
ASA 2 = mild-moderate systemic disease, medically well-controlled
ASA 3 = Severe disease which limits activity but not threat to life (not incapacitating)
ASA 4 = Severe + incapacitating (constant threat to life)
ASA 5 = patient not expected to survive 24 hours with or without surgery
ASA 6 = Brain dead whose organs are being harvested

Question 32

In terms of postponing surgery, what would your general advice be for a patient with