Anaesthetics Flashcards
1
Q
What is the name for assessing fitness for surgery?
A
ASA grading
2
Q
What are the stages of ASA grading?
A
- Normal healthy patient
- Mild systemic disease/ >80
- Systemic disease that causes definite functional limit to life
- Severe systemic disease that’s a constant threat to life.
- Moribund patient unlikely to survive 24hours without surgery
3
Q
What are the grades of surgery?
A
- MINOR, excision of skin lesion, drainage of abscess
- INTERMEDIATE, inguinal hernia, tonsillectomy
- MAJOR, thyroidectomy, total abdo hysterectomy
- MAJOR+, colonic resection, total joint replacement
4
Q
What are the fasting times for surgery?
A
8hours: Heavy meal
6hours: Non-human milk, formula, light meal
4hours: Breast milk
2hours: Clear liquids (no limit)
Alcohol: At least 24hours before surgery
5
Q
What delays gastric emptying?
A
Metabolic: DM, ESKD Anatomical: Pyloric stenosis Trauma Mechanical: Pregnancy, obesity High fat content Anxiety
6
Q
How is the airway assessed before surgery?
A
- Hx & Ex
- Mallampatti
- Teeth
- Thyromental & sternomental distance
- Neck movement
- 1-2-3
- Cormack & Lehane
7
Q
What are METs?
A
Metabolic Equivalents 1= eating & dressing 3= light household activity/ walk 100m @ 2-3mph 4= climb stairs 6-7= short run
8
Q
What components make up a general anaesthetic?
A
Amnesia
Analgesia
Akinesis
9
Q
What are the most common inducing agents
A
Propofol
Thiopentone
Ketamine
Etomidate
10
Q
Propofol:
- Properties
- Reason for use
- Side effects
A
- MOST COMMON
- Lipid based
- Excellent suppression of airway reflexes & dec PONV (anti-emetic properties)
- SE: drop in HR & BP, pain on inj, involuntary movements
11
Q
Thiopentone:
- Properties
- Reason for use
- Side effects
- Example
A
-Barbituate
-Faster acting than propofol
-RSI
Antiepileptic properties & protects the brain
-SE: drops BP, rise HR, rash & bronchospasm, intraA injection
-CI in porphyria
-Pt w/GI perf
12
Q
Ketamine:
- Properties
- Reason for use
- Side effects
- Example
A
- Dissociative
- Anterograde amnesia
- Slow onset (90secs)
- Activates sympathetic system
- Bronchodilation
- Moderate-strong analgesic properties
- SE: Rise in BP & HR, N&V, emergence phenomenon
- Change dressings for burns patients
13
Q
Etomidate:
- Properties
- Reason for use
- Side effects
- Example
A
- Rapid onset
- Haemodynamically stable
- Lowest incidence of hyperS
- SE: pain on inj, spont movements, adreno-cortical suppression, PONV
- HF patient
14
Q
What is adreno-cortical suppression & what is it associated with?
A
Etomidate
Cortisol level suppressed >72hours after bolus. Not used in critically ill/septic patients
15
Q
What is the problem with intra-arterial injection & what is this associated with?
A
Thiopentone
Blockage of capillaries due to large crystals can lead to thrombosis & gangrene
16
Q
When are inhaled agents used?
A
After inducing agent to maintain amnesia and continued till the end of the operation
17
Q
Name the most common inhaled agents
A
Isoflurane Sevoflurane Desflurane Enflurane NO
18
Q
What is MAC?
A
Minimum alveolar concentration
Concentration of inhaled agents
19
Q
Isoflurane:
- MAC
- Properties
- Example
A
- 1.15%
- Can be used as inhaled amnesic
- Least effect on organs
- Donor-recipient operations
20
Q
Sevoflurane:
- MAC
- Properties
- Example
A
- 2%
- Sweet smelling, inhalation induction
- Chubby kid w/ no IV access
21
Q
Desflurane:
- MAC
- Properties
- Example
A
- 6%
- Can be used as inhaled amnesic
- Low lipid solubility, rapid on/offset, long operations
- 7hr op for finger re-implant
22
Q
MAC for NO & Enflurane
A
NO: 104%- cannot give 1 MAC of NO
En: 1.6%
23
Q
Name the short-acting opioids & when they would be used?
A
Fentanyl Alfentanil Remifentanil Used: Intra-operatively Suppress response to laryngoscope Surgical pain
24
Q
Name the long-acting opioids and when they would be used?
A
Morphine
Oxycodone
Used: Intra-operatively
Post-operatively
25
What type of pain is tramadol used for?
Nociceptive
| Neuropathic
26
What type of pain is morphine used for?
Nociceptive
Acute
Severe
Cancer pain
27
How do GAs stop movement?
As action potential arrives at NM junction, Acetylcholine is released which causes depolarisation of Nicotinic receptors leading to muscle contraction.
28
What is the pathophysiology of the 2 types of akinesic agents?
Depolarising: Similar to acetylcholine on nicotinic receptors slowly hydrolysed by acetylcoA. Muscle contraction then fatigues
Non-depolarising: Block nicotinic receptors so muscle relaxes
29
Name the main types of akinesic agents
```
Suxamethonium- RSI
Atracurium
Mivacurium
Rocuronium
Vercuronium
Pancuronium
```
30
Name the depolarising agents
Suxamethonium
| Succinylcholine
31
Name the non-depolarising agents & describe some of their characteristics
Less SE, slow onset & variable duration, compete with Ach for nicotinic receptors
```
Atracurium- Short acting
Mivacurium- Short acting
Rocuronium- Intermediate
Vercuronium- Intermediate
Pancuronium- Long acting
```
32
How are muscle relaxants reversed?
Neostigmine: Anti-cholinesterase prevents breakdown of acetylcholine (SE= brady)
Glycopyrrolate: Antimuscarinic (SE= N&V)
33
What anti-emetics can be used post-op?
```
5HT3: Ondansetron
Anti-Histamine: Cyclizine
Steroid: Dexamethasone
Phenothiazine: Prochlorperazine
Anti-dopaminergic: Metoclopramide
```
34
What is the definition of a local anaesthetic
Reversibly prevents transmission of the nerve impulse in the region to which it is applied without affecting consciousness.
35
What is the composition of a LA?
Ester
| Amide
36
Describe esters
```
Less stable in sol
Metabolised by PABA associated w/allergies
S-A: Procaine, Cocaine, Benzocaine
M-A: Prilocaine
L-A: Amethocaine
```
37
Describe amides
Heat stable (autoclaved)
Rare for allergies
M-A: Lidocaine/lignocaine, Mepivacaine
L-A: Bupivacaine, Levobupivacaine
38
What is the safe dosage of LA?
Lignocaine: 3mg/kg
(levo)Bupivacaine: 2mg/kg
Prilocaine: 6mg/kg
39
What is the safe dose of LA with adrenaline?
Lignocaine: 7mg/kg
(levo)bupivacaine: 2mg/kg
Prilocaine: 9mg/kg
40
What is the MOA of LA?
1. Inhibition of voltage sensitive Na channel in axon preventing action potential
2. Membrane stabilisation effect
3. Prevent pain by causing reversible block of conduction along nerve fibres
4. Exert toxicity by blocking Na channels found in the brain or heart:
a. If plasma levels rise SLOWLY CNS is affected first (excitatory symptoms due to inhibition of GABA receptors- metallic taste, dizziness, slurred speech, diplopia, tinnitus, muscle twitching, confusion, convulsions)
b. At high concentrations there is widespread Na channel blockade with generalised neuronal depression leading to coma, respiratory & cardiac arrest
41
How is LA toxicity treated?
```
Stop inj & call for help
Maintain airway, give 100% O2
Establish IV access
Control seizure (benzo/propofol/thiopental)
ARREST=CPR
IV intralipid (lipid emulsion)
```
42
Where is a spinal block & an epidural placed?
BOTH: Skin, Subcut fat, Supraspinus lies, Spinal logs, Ligamentum flavum
S: Through dura & arachnoid to CSF space: L2-S2
E: Space between ligamentum flavum & dura below L1
43
When is a spinal & epidural used?
S: Ops on lower half of the body
E: Intra-op analgesia & <72hours post-op
44
How is a spinal & epidural given & onset?
S: Small amount Single injection, rapid onset (5-10mins)
E: Epidural catheter, onset 15-30mins, reliant on catheter placement
45
Risk factors for PONV?
Female
Previous episodes
Non-smoker
46
What factors make up the anaesthetic safety checklist?
- Experienced & trained assistant to help with induction
- Fasted appropriately
- IV access that is functional
- On a table that can be rapidly tilted
47
What is the NCEPOD classification?
Classification of intervention
- Immediate
- Urgent
- Elective
- Expedited
48
What are the anaesthetic emergencies?
LA toxicity
Airway: Laryngospasm, can't intubate/can't ventilate
Anaphylaxis
Malignant hyperthermia
49
What are the SE of depolarising agents?
```
Muscle pains
Fasciculations
HyperK
Malignant hyperthermia
Rise in ICP, IOP, gastric pressure
```
50
What is the pathway of identifying a potential organ donor patient?
1) Inform SNOD of potential donors
| 2) Speak to family
51
Can you smoke before an operation?
No-ideally stop 48-72hours
Smoking makes airway more irritable
Raised Hb levels
