Anaesthetics Flashcards
(120 cards)
1
Q
Propofol dose?
A
1.5-2.5 mg/kg
2
Q
Thiopentone dose?
A
4-5 mg/kg
3
Q
Ketamine dose?
A
1-1.5 mg/kg
4
Q
Etomidate dose?
A
0.3 mg/kg
5
Q
Benefits of propofol?
A
- Good suppression of airway reflexes – no laryngospasm.
* ↓Incidence of PONV.
6
Q
Benefits of thiopentone?
A
- Faster than propofol
* Antiepileptic properties and protects brain.
7
Q
Benefits of ketamine?
A
• Dissociative amnesia and profound amnesia
8
Q
Unwanted effects of propofol?
A
- ↓HR and BP
- Pain on injection
- Involuntary movements
9
Q
Unwanted effects of thiopentone?
A
- ↓BP but ↑HR
- Histamine release –> rash/bronchospasm
- Intrarterial injection –> crystalise in smaller vessels –> thrombosis + gangrene
- Contraindicated in prophyria
10
Q
Unwanted effects of ketamine?
A
- N + V
* Emergence phenomenon – vivid dreams, hallucinations
11
Q
Benefits of etomidate?
A
- Rapid onset
- Haemodynamic stability
- Lowest incidence of hypersensitivity reaction
12
Q
Unwanted effects of etomidate?
A
- Pain on injection
- Spontaneous movements
- Adreno-cortical suppression
- High incidence PONV
13
Q
General stuff about propofol?
A
• Lipid based (white emulsion)
14
Q
General stuff about thiopentone?
A
• Used for rapid sequence induction
15
Q
General stuff about ketamine?
A
- Slow onset (90 secs)
* Sympathetic stimulation –> ↑HR/BP, bronchodilation
16
Q
General stuff about etomidate?
A
• Shouldn’t use in critically ill patients with septic shock –> ↑mortality
Steroid injection
17
Q
What is MAC?
A
Minimum alveolar concentration or MAC is the concentration of a vapour in the lungs that is needed to prevent movement (motor response) in 50% of subjects in response to surgical (pain) stimulus.
18
Q
Nitrous oxide MAC?
A
104%
19
Q
Isoflurane MAC?
A
1.15%
20
Q
Sevoflurane MAC?
A
2%
21
Q
Deflurane MAC?
A
6%
22
Q
Enflurane MAC?
A
1.6%
23
Q
Benefits of isoflurane?
A
• Least effect on organ blood flow - good for transplant
24
Q
Benefits of sevoflurane?
A
- Sweet smelling
- Inhalational induction
- Good if you don’t want to do multiple cannula attempts while awake, or if scared of needles etc.
25
Benefits of deflurane?
* Rapid onset and offset
* Low lipid solubility --> pt will wake up faster after op.
Good for long operations
26
Suxamethonium dose?
1-1.5 mg/kg
27
Mechanism of suxamethonium?
Act similar to Ach on nAchR but are very slowly hydrolysed by AchE. Cause fasciculation, muscle then fatigues and relaxes.
28
Side effects of suxamethonium?
* Muscle pains
* Fasciculations
* Hyperkalaemia
* Malignant hyperthermia
* ↑ICP, ↑IOP and ↑gastric pressure – don’t use in patients with eye injury --> expulsion of eyeball contents.
29
Mechanism of non-depolarising muscle relaxants?
Compete with Ach for nAchR.
30
Benefits of non-depolarising muscle relaxants?
• Slow onset and variable duration – less side effects.
31
Short-acting non-depolarising muscle relaxants?
Atracurium, Mivacurium
32
Intermediate-acting non-depolarising muscle relaxants?
Vecuronium, Rocuronium
33
Long acting non-depolariisng muscle relaxants?
Pancuronium – cannot reverse within 1 hou
34
Name a muscle relaxant reversal agent?
Neostigmine - anti-cholinesterase, prevents breakdown of Ach
35
Adverse effects of neostigmine?
• Ach is ↑ all over body --> antimuscarinic effects (↓HR etc.)
36
What is neostigmine combined with?
• Combined with antimuscarinic agent – Glycopyrrolate - blocks muscarinic receptors so neostigmine only effective at NMJ.
37
Short acting opioids?
* Fentanyl
* Alfentanil
* Remifntanil
38
Long acting opioids?
* Morphine
| * Oxycodone
39
General stuff about short-acting opioids?
* Take longer than induction agents (1-5 minutes) – give before induction agent.
* Intra-op analgesia, suppress response to laryngoscopy, surgical pain.
40
Name some analgesics that can be given IV?
Paracetamol
Parecoxib
Kertorolac
Dihydrocodeine
41
3 drugs used for hypotension?
Ephedrine
Phenylepherine
Metaraminol
42
Action and mechanism of ephedrine?
↑HR + ↑inotropy ↑BP
Direct and indirect action – α and β receptors
43
Action and mechanism of phenylepherine?
Vasoconstriction + ↓HR --> ↑BP
Direct action – α receptors
44
Action and mechanism of metaraminol?
Vasoconstriction --> ↑BP
Direct and indirect action – predominantly α receptors
45
3 drugs used in severe hypotension/ICU
Noradrenaline, Adrenaline, Dobutamine
46
Anti-emetics and their types?
Ondansetron (1) - 5HT3 blocker
Dexamethasone (2) - Anti-histamine
Cyclizine (3) - Steroid
Prochlorperazine (Stemetil) - Phenothiazine
Metaclopramide - Anti-dopaminergic
47
What is Mallampati score?
I - complete visualization of soft palate
II - complete visualization of the uvula
III - visualization of only the base of the uvula
IV - soft palate not visible at all
48
List of things to cover in perioperative assessment?
```
CVS
Resp
Airway
Previous anaesthetic history
GI
PMH
Medication Hx
History of allergies
Examination
```
49
Things to ask in CVS?
Chest pain (SOCRATES), hypertension, PND, orthopnoea, exercise tolerance
50
Things to ask in resp?
Asthma, any evidence of chest infection i.e. cough, smoking
51
Things to ask in airway?
Teeth, dentures, neck movements, mouth opening (Mallampatti score)
52
Things to ask in previous anaesthetic history?
Any problems, PONV, pain relief, family history of anaesthetic problems
53
Things to ask in GI?
History of GORD, last meal time
54
Things to ask in PMH?
Diabetes, epilepsy, renal disease, thyroid problems, TIA, stroke or other
55
Purpose of perioperative assessment?
1. Allay fear and anxiety
2. Identify potential anaesthetic difficulties and medical conditions
3. Improve safety by assessing and quantifying risk
4. Optimise plan of peri-operative care
5. Provide opportunity for explanation and discussion (consent – only needs to be verbal for anaesthesia).
56
Why aren't perioperative investigations done in all patients?
* Expensive
* Labour intensive
* May delay surgery
* Associated morbidity: pain, haematoma, infection etc.
57
What things affect what perioperative investigations are necessary?
Age
ASA grade
Nature of the surgery
58
What is ASA grading?
* A physical status classification system for assessing fitness for surgery
* For emergency cases the suffix ‘E’ is used.
59
Summary of ASA grading?
1 - A healthy patient with no systemic disease
2 - Mild to moderate systemic disease with no functional limitation.
3 - Severe systemic disease imposing functional limitation on patient
4 - Severe systemic disease which is a constant threat to life
5 - Moribund patient who is not expected to survive with or without the operation
6 - A brainstem-dead patient whose organs are being removed for donor purposes.
60
Summary of surgical grading?
1 - (minor) Excision skin lesion; Cystoscopy: Drainage of an abscess
2 - (intermediate) Inguinal hernia; Tonsillectomy
3 - (major) Hysterectomy; Thyroidectomy
4 - (major+) Joint replacement; thoracic operations, Total hip replacement, Radical neck dissection
61
Which investigations do people >80yrs get?
FBC, U+E, ECG
62
Circumstances where <60s need investigations?
FBC - SG >3
U+E - SG >4
ECG - never
63
Circumstances where 60-80 need investigations?
FBC - SG >2
U+E - SG >3
ECG - SG >3
64
Special circumstances for investigations?
* African / Afro-Caribbean origin or positive family history : Sickle test
* Women: Pregnancy test for women who may be pregnant.
* Intensive care admission, Respiratory disease in ASA 3 or 4: CXR
65
What questions need to be asked if patient is not fit for surgery?
* Is the surgery emergency or elective?
* How will any further investigations add to management?
* If I postpone, what benefit will the patient get? (i.e. better physiology, reduced risk etc.)
66
Problems with inadequate fasting?
Pulmonary aspiration. As low as 30 mL can be associated with significant morbidity and mortality.
67
Problems with prolonged fasting?
Headache, light-headedness, discomfort, increased anxiety, increased incidence of N+V, hypotension, metabolic disturbances.
68
Fasting time for solids and milk-containing drinks?
6 hours - fat in milk curdles and thickens
69
Fasting time for breastfed infants?
4 hours - human milk has less fat
70
Fasting time for clear fluids?
2 hours - Clear means you can see through the fluid. Minimal sip (30mL allowed to take tablets).
71
Fasting time for alcohol?
24 hours - delays gastric emptying
72
Fasting time for boiled sweets/chewing gum?
Avoid but carry on with surgery - Leads to increased gastric volume and acidity.
73
Indication for rapid sequence induction?
Full stomach for any reason i.e. high risk of aspiration.
74
What are factors that delay gastric emptying?
* Metabolic = diabetes, end stage renal failure
* Anatomical causes = pyloric stenosis
* Mechanical = pregnancy, obesity
* Trauma = RTA, head injury
* Others = high fat content, anxiety
75
Process of rapid sequence induction? (preoxygenation)
Preoxygenation
* Tight fitting face mask for three minutes or 5 full vital capacity breaths, EtO2 concentration > 90
* Rationale: replace functional residual capacity (FRC) with oxygen
76
Process of rapid sequence induction? (Drugs)
* Thiopentone: 4 – 5 mg/kg, onset: 15 -30 seconds duration, Duration of action: 4- 8 minutes
* Propofol: 1.5 – 2.5 mg/kg, Onset: 30 seconds, DOA: 2 – 6 minutes
* Suxamethonium: 1 -1.5 mg/kg: DOA 6 minutes
77
Process of rapid sequence induction? (Technique)
* Cricoid Pressure: (Cricoid cartilage is a complete ring)
* No ventilation
* Remove cricoid after confirmation of tube position (EtCO2) + other signs (direct visualisation, moisture in expired air, chest expansion, chest auscultation)
78
What are the four CEPOD classifications?
Immediate/emergency
Urgent
Expedited/scheduled
Elective
79
Description/example of emergency surgery?
◦ Immediate life, limb or organ-saving intervention.
◦ Resuscitation simultaneous with intervention.
◦ Normally within minutes of decision to operate.
Repair of ruptured aortic aneurysm, Fasciotomy
80
Description/example of urgent surgery?
◦ Intervention for acute onset or clinical deterioration of potentially life or limb threatening conditions.
◦ Time available for resuscitation.
◦ Normally within hours of decision to operate.
Debridement plus fixation of fracture, Intestinal perforation
81
Description/example of expedited/scheduled surgery?
◦ Patient requiring early treatment where the condition is not an immediate threat to life or limb. ◦ Normally within days of decision to operate.
Repair of tendon and nerve injuries, Excision of tumour with potential to bleed or obstruct
82
Description/example of elective surgery?
◦ Intervention planned or booked in advance of routine admission to hospital. Timing to suit patient, hospital and staff. (18 weeks initiative)
Elective AAA repair, Laparoscopic cholecystectomy
83
Describe physiology of pain?
1. First order neuron - Site of injury --> dorsal root ganglion (cell body of 1st order neurons) –spinal cord (peripheral nerve like radial nerve).
2. Second order neuron - Spinal cord --> thalamus (lateral spinothalamic tract)
3. Third order neuron. Thalamus --> Somatosensory area one and two in post central gyrus of parietal cortex (thalamo-cortical pathways)
84
`Dose of paracetamol?
1 gram QDS
85
Dose of ibuprofen?
400mg TDS
86
Dose of diclofenac?
50mg TDS
87
Dose of dihydrocodeine?
30mg QDS
88
Dose of coedine phosphate?
30-60mg QDS
89
Dose of tramadol?
50-100mg QDS
90
Dose of oramorph?
5-20mg 4 hourly
91
Contraindications/ cautions for NSAIDs?
Sensitive bronchospasm, peptic ulcer disease, bleeding concerns, renal impairment
* Caution in IHD, hypertension and stroke. Some agents, particularly COX2s, have been associated with higher risk of MI and stroke.
92
Principle of PCA?
A syringe pump containing the analgesic drug is connected to the patient’s IV cannula and the patient uses a button to request a bolus of analgesia.
A safe steady state of analgesia using frequent small boluses to maintain rather than ‘spikes’ of alternating pain and analgesia with PRN medications.
93
Typical regimen of PCA?
1mg Morphine allowed every 5 minutes (‘lock-out’ period)
94
Lock-out period in PCA?
The patient can press the button as often as they feel is required but the device will only allow a bolus to be administered every 5 minutes.
95
Inherent safety mechanisms in PCA?
- Small bolus doses
- Lock-out period (usually 5 minutes)
- Opioid overdose will usually lead to drowsiness therefore patient will not be able to keep pressing. - Better monitoring for the patient through use of dedicated observation charts
96
Mechanism of local anaesthetics?
Local anaesthetics block the transmission of the nerve impulse transiently.
Inhibition of Sodium channel in axon preventing K/Na exchange and transmission of nerve impulse
The sensory information is blocked at the site of application and does not reach the brain
97
What two groups are LAs composed of?
Lipid-soluble hydrophobic aromatic group + charged, hydrophilic amide group.
Joined together by either an ester or amide link --> ESTERS and AMIDES
98
Examples of esters?
* Procaine, amethocaine (Ametop), cocaine (not really used anymore)
99
Examples of amides?
* Ropivacaine, levobupivacaine, bupivacaine, mepicaine, prilocaine
100
Maximum dose of lignocaine with and without adrenaline?
3mg/kg
| 7mg/kg with adrenaline
101
Max dose of bupivocaine/ levobupivocaine with and without adrenaline?
2mg/kg SAME WITH ADRENALINE
102
Max dose of prilocaine with and without adrenaline?
6mg/kg
| 9mg/kg with adrenaline
103
Which local anaesthetic is longest acting?
Bupivacaine/levobupivacaine
104
Which LA is quicker acting, shorter duration?
Lignocaine
105
How to calculate safe dose of local anaesthetic?
* % concentration --> multiply by 10 --> content of LA in mg/ml (0.25% bupivacaine contains 2.5mg/ml)
* Calculate max dose – multiply max dose in mg/kg by weight
* Divide max dose by concentration in mg/ml
106
Features of local anaesthetic toxicity?
* Tingling around mouth
* Ringing in ears
* Tonic-clonic seizure
* Cardiovascular/ respiratory failure after
107
Management of LA toxicity?
* ABCDE approach
* 100% oxygen
* Call for help
* Tell surgeons to stop
* Send for crash trolley and intralipid
* Start IV fluids
* If no palpable pulse/poor respiratory effort --> initiate basic/advanced life support as per algorithms, good supportive care.
* Consider use of intralipid – reduces concentration of free local anaesthetic by absorbing it from the blood.
108
What are the layers of the spinal cord?
1. Dura mater
2. Arachnoid mater
3. Pia mater
109
What level does the spinal cord end?
Lower border of L1
110
Where does subarachnoid space end?
S2
111
Between which vertebrae can spinal be done?
Below L2 and up to S2
L2/3
L3/L4
L4/L5
(Lowest level possible to minimise risk of damage to spinal cord)
112
Where does the epidural space end?
saccrococcygeal hiatus.
113
Where can epidural be done?
Any level - but risk of damage to the cord if it is done above the level of L1.
114
Where would epidural be done for labour and laparotomy respectively?
Labour - same as spinal
| Laparotomy - thoracic level (hypotension)
115
Differences in essence of spinal and epidural?
Spinal = single shot injection of small volume anaesthesia mix (2-3 mls LA +/- opioid) directly into CSF
Epidural = Infiltration of LA +/- opioid mix via epidural catheter
116
Differences in onset of spinal and epidural?
Spinal = more rapid onset (5-10 mins)
Epidural = Slower onset (15 -30 minutes)
117
Differences in predictability between spinal and epidural?
Spinal = more predictable/reliable for anaesthesia
Epidural = Effect is reliant on catheter position (e.g. unilateral blocks, missed segments, patchy blocks etc.)
118
Differences in density of block between spinal and epidural?
Spinal = denser block, particularly motor
Epidural = less motor block
119
Differences in duration of block between spinal and epidural?
Spinal = Good anaesthesia for 2-3 hours, analgesia may last longer (especially if opioid used)
Epidural = Usually used for titratable anaesthesia/analgesia for a longer period (up to 72 hours)
120
Advantages of regional anaesthesia over opioids?
Better in patients with respiratory disease as painful wounds may lead to reduced lung expansion and increased risk of post-op respiratory complications, patients in whom intravenous analgesics may be less desirable (e.g. obstructive sleep apnoea, PONV) etc.
