Anaesthetics

Question 1

List some factors that need to be taken into account in an airway assessment.

Answer 1

Mouth opening, teeth, facial hair, neck extension, thyromental distance >/=6.5cm, obesity, jaw protrusion, mallampati score

Question 2

What is Pain?

Answer 2

An unpleasant sensory or emotional experience associated with actual or potential tissue damage

Question 3

What signs might indicate hypovolaemia?

Answer 3

Raised HR, RR, dropped Bp
Reduced urine output
History of poor fluid in take or fluid loss
Reduced skin turgor, cool peripheries, postural hypotension, CRT >2, dry mucous membranes

Question 4

What is the max maintenance fluids you can prescribe?

Answer 4

100mls/hr

Question 5

What are the daily requirements of water and Na, CL, K , glucose?

Answer 5

30ml/kg/day water
1-2mmol/L/kg/day NaCl
1 mmol/L/kg/day K
50-100g glucose per day

Question 6

What electrolytes are in Saline and hartmanns?

Answer 6

Saline - NaCL

Hartmanns - Na, K, Ca, Cl, HCO3

Question 7

Where is the vomiting centre?

Answer 7

Medulla oblongata
Low level stimulation - nausea
High level stimulation - vomiting

Question 8

List some inputs to the vomiting centre.

Answer 8

Chemoreceptor trigger zone - Dopamine, ACH, serotonin, histamine
Higher cortical centres - GABA
Vestibular apparatus and cerebellum - ACH, histamine
Stomach/ intestines - ACh, Dopamine, histamine, serotonin
Raised ICP or brain mets directly putting pressure on VC

Question 9

Where is the Chemoreceptor trigger zone and what triggers it to stimulate the vomiting centre?

Answer 9

Outside the BBB
Area postrema at the base of the 4th ventricle
Electrolyte disturbances (hyperCa, HypoNa), biochemical changes, medication (e.g. chemotherapy induced N&V)

Question 10

Where does the dopamine antagonist Metaclopramide work and what might it be used first line for?

Answer 10

CTZ, GI tract

1st line in: Impaired gastric emptying, biochemical causes of vomiting

Question 11

Where does cyclizine act and when might it be used first line?

Answer 11

Vomiting centre, vestibular systen

1st line in: Complete bowel obstruction, IC cause/motion sickness

Question 12

Where does Ondansetron act and when might it be used?

Answer 12

CTZ, vagal nerve

1st line in: Chemo/radiotherapy induced N&V, opiate induced N&V, GI distension/obstruction, post-op

Question 13

Where does the dopamine antagonist Haloperidol act and when might it be used 1st line?

Answer 13

CTZ

1st line in: Biochemical, hiccups, delirium

Question 14

Where does Levomepromazine act and when is it used?

Answer 14

Everywhere - Dopamine, serotonin, muscarinic, histamine

Due to SE it is used 2nd line when 1st line has failed

Question 15

Explain the vomiting reflex,

Answer 15

1. Stimulation to the Vomiting center
2. VC coordinates reflex throughout CN V, VII, IX, X, XII
3. Prodrome - Hypersalavation, sweating, pallor, tachycardia
4. Glottis closes and soft palate raises to close off airway
5. Deep inspiration and diaphragm contracts
6. GO sphincter and funds of stomach relax
7. Abdominal muscles contract forcefully
8. Anti-peristalitic waves
9. Increased pressure forces chyme up from the stomach and out of the mouth

Question 16

What is the triad of anaesthesia and give some examples of agents.

Answer 16

Unconsciousness - propofol (GABA agonist), ketamine & NO (antagonises NMDA)
Muscle relaxants - Recuronium, suxamethonium
Analgesia - IV paracetamol or opioids

Question 17

What drugs could you reverse the effect of the neuromuscular blockers suxamethonium or rocuronium?

Answer 17

Neostigmine or rocuronium

Question 18

List some pre-op risk scores.

Answer 18

NSQIP
SORT
POSSUM
They help calculate the risk of mortality

Question 19

What are the fasting guidelines?

Answer 19

Food and fizzy drinks - 6 hours
Clear fluids - 2 hours
Milk - 6 hours
Breast milk - 4 hours
Chewing gum - 2 hours

Question 20

How would you define a major haemorrhage?

Answer 20

Loss of more than 1 blood volume within 24 hours
Rate >150ml/min
50% of blood volume in under 3 hours

Question 21

How might you assess nutritional status?

Answer 21

BMI
Grip strength
Tricep skin fold thickness

MUST

Question 22

Explain the physiological response to pain.

Answer 22

Pain causes release on endogenous amines - NA, adrenaline, dopamine, etc - knock on effect
Inc HR and contraction - inc myocardial oxygen demand - If CAD - Type 2 MI??
Rapid resps, shallow breathing
Reduced wound healing due to reduce blood flow to wound and reduced oxygen and blood to wound, reduced healing in hypoglycaemia due to stress response
Coagulopathy - DVT/PE

Question 23

Explain the analgesia pain ladder.

Answer 23

NSAID ± Aspirin ± paracetamol
+ Tramadol, codeine, oxycodone
+ Morphine, hydromorphone, fentanyl, methadone, buprenorphine

Question 24

What are some post-op causes of pyrexia?

Answer 24

WIND - 1-2d - pneumonia, atelectasis, aspiration
WATER - 3-5d - UTI
WALKING - 5+ - DVT/PE
WOUND - 5-7d - surgical site infection, abscess
What did I do? 7+ - line infection, sepsis, transfusion reaction, drugs