Preoperative Care Flashcards
(95 cards)
1
Q
List the common medications that should be stopped prior to surgery
A
- COCP (4 weeks prior to major surgery)
- Tamoxifen (4 weeks prior to major surgery)
- HRT (4 weeks prior to major surgery)
- Antiplatelets (stop 7-14 days prior)
2
Q
List the common drugs that should be held of the day of surgery
A
- ACE-i
- ARBs
- Diuretics
- Diabetic treatment (alternative should be arranged)
- Warfarin/Aspirin/Clopidogrel (unless coronary stent)
- Lithium
- NSAIDs
3
Q
How should oral medications be given on the days of surgery
A
With a sip of water even if NBM
4
Q
Which patients should receive perioperative steroid cover
A
- Adrenal insufficiency on steroids
- Undergoing pituitary or adrenal surgery
- On systemic steroid therapy >7.5mg/day for >1 week prior to surgery
- Those who have received >1 month steroid course in the past 6 months
5
Q
What are the mineralocorticoid side effects of steroids
A
- Sodium and water retention
- Potassium loss
- Metabolic alkalosis
6
Q
What are the Prednisolone and Dexamethasone equivalent doses of 100mg Hydrocortisone
A
- Prednisolone 25mg
- Dexamethasone 4mg
7
Q
What does Warfarin inhibit
A
- Vitamin K-dependent clotting factors (2, 7, 9, 10)
- Protein C and S
8
Q
How do you reverse warfarin:
A) >24 hours
B) Immediately
A
A) Vitamin K 10mg
B) FFP 15ml/KG
9
Q
How should Warfarin be managed perioperatively
A
- Stop 3-5 days before
- Replace with heparin
10
Q
INR targets for:
A) Open surgery
B) Invasive procedures
A
A) <1.2
B) <1.5
11
Q
Mechanism of action of Heparin
A
- Binds to antithrombin 3
- Inhibits factors 2a, 9a, 10a, and 12a
12
Q
How often should APTT be checked whilst on heparin infusion
A
6 hourly
13
Q
How is LMWH reversed
A
Protamine 1mg per 100 units
14
Q
Describe the Lee Index
A
Individual predictor of cardiac risk based on 6 parameters
- History of IHD
- History of CVA
- HF
- T1DM
- Impaired renal function
- High risk surgery
15
Q
List the cardiac effects of general anaesthetic
A
- SVR decreases (20-30% at induction)
- Tracheal intubation reduces BP by 20-30mmHg
- Myocardial depression
- Increased cardiac irritability
16
Q
What is the minimum interval between MI and elective surgery
A
6 months
17
Q
How should T2DM be managed prior to surgery
A
Continue normal oral hypoglycaemics until the morning of surgery, except Metformin and Chlorpropamide which may need to be stopped earlier due to risk of lactic acidosis
18
Q
Risk of MI if surgery performed within 3-6 months of previous MI
A
16%
19
Q
What is the minimal accepted urine output guiding adequate renal perfusion
A
0.5ml/kg/hr
20
Q
What is the best blood marker for assessing response to nutrition supplementation
A
Serum transferrin
21
Q
Criteria for malnourishment
A
- BMI <18.5
- Unintentional weight loss >10% over 3-6 months
- BMI <20 and unintentional weight loss >5% over 3-6 months
22
Q
List the risks associated with TPN
A
- Hyperosmolarity
- Lack of glycaemic control
- Micronutrient deficiencies
- Liver dysfunction
- Pancreatic atrophy
- Fluid overload
23
Q
What scan should be performed prior to commencing home TPN
A
Bone densitometry
24
Q
In whom should gastrostomy be considered for nutrition
A
If gastric feeding likely required for >4 weeks
25
How does pancytopenia occur when using TPN
B12/Folate deficiency
26
How many mg/ml in a 1% solution
10mg/ml
27
Maximum dose of Lidocaine with and without adrenaline
- Without = 3mg/kg
| - With = 7mg/kg
28
Maximum dose of Bupivicaine with and without adrenaline
- Without = 2mg/kg
| - With = 2mg/kg
29
Maximum dose of Prilocaine with and without adrenaline
- Without = 6mg/kg
| - With = 9mg/kg
30
What are the symptoms of systemic local anaesthetic toxicity
- Perioral tingling
- Anxiety
- Tinnitus
- Drowsiness
- Seizures
- Coma
- Apnoea
- CV collapse
- Paralysis
31
What is the reversing agent for local anaesthetics
Lipid emulsion (intralipid 20%) at 1.5ml/kg over 1 minute
32
How is prilocaine toxicity treated
Methylene blue
33
How is a field block performed for inguinal hernia repairs
Direct infiltration of the ilioinguinal nerve above the ASIS
34
When should a heparin infusion be stopped prior to surgery
6 hours
35
What type of block should be used for the fingers and how is this performed
- Ring block
- NO ADRENALINE
- Inject either side of the digit at the level of the webspace
36
When might a sciatic block be used
Foot and ankle surgery
37
How is a sciatic block performed
Injection 2cm lateral to the ischial tuberosity at the level of the GT
38
Outline how a Bier's block is performed
1. IV access in both arms
2. Exsaguinate limb with Eschmark bandage
3. Apply double cuff touniquet
4. Inflate upper cuff to 300mmHg
5. Inject 40ml of 0.5% Prilocaine
6. Inflate lower cuff
7. Release upper cuff
39
Which dural space is used for spinal anaesthesia
Subarachnoid
40
What level is the needle inserted for spinal anaesthesia
L1-2
41
What dural space is used for epidural anaesthesia
Extradural space
42
What precautions must be taken with spinal catheters and anticoagulation
Catheters must not be removed whilst anticoagulated (remove 12 hours post low-dose LMWH and delay two hours before next dose)
43
What type of drug is Lidocaine
Amide local anaesthetic (also antiarrhythmic)
44
What is the primary precaution with Bupivacaine
Cardiotoxicity
45
What is the mechanism of action of Bupivicaine
Binds to the intracellular portion of sodium channels and blocks sodium influx into nerve cells to prevent depolarisation
46
Why is bupivicaine contraindicated in regional blockage
Due to its cardiotoxicity in the event that the tourniquet fails
47
What is the local anaesthetic of choice for IV regional anaesthesia
Prilocaine
48
At what pH do local anaesthetics become less effective
Acidic environments e.g. abscess
49
Which drugs contraindicate the use of adrenaline
- TCAs
| - MAOIs
50
What is the major side effect of Prilocaine
Methaemoglobinemia
51
Why do spinal anaesthetics cause hypotension
Cause loss of sympathetic tone
52
Outline ASA grading
1. Normal healthy individual
2. Mild systemic disease
3. Severe systemic disease that limits activity but is not incapacitating
4. Incapacitating disease that is a constant threat to life
5. Moribund patient not expected to survive
53
What are the aims of anaesthetic premedication
- Anxiolytic
- Enhances hypnotic effect of GA
- Amnesia
- Dries secretions
- Antiemetic effect
- Increases vagal tone
- Modifies gastric contents
54
Agent to reverse Benzodiazepines
Flumazenil
55
Side effects of Hyoscine
- Bradycardia
- Confusion
- Ataxia
56
What is the agent of choice for rapid-sequence induction
Sodium thiopentone
57
What is the agent of choice for induction of anaesthesia in those who are haemodynamically unstable and why
- Ketamine
| - Produces little myocardial depression
58
What is the agent of choice for induction of anaesthesia in daycase surgery
Propofol
59
Which induction agents have antiemetic properties
Propofol
60
Which induction agent is associated with adrenal suppression
Etomidate
61
Why can thiopentate not be used with laryngeal airways
Sensitises the pharynx
62
What are the common depolarising neuromuscular blockers
Suxamethonium
63
What is the mechanism of action of Suxamethonium
Inhibits the action of acetylcholine at the neuromuscular junction
64
What is the fastest onset muscle relaxant
Suxamethonium
65
What are the adverse affects of suxamethonium use
- Hyperkalaemia
- Malignant hyperthermia
- Delayed recovery
66
Which anaesthetic agent is associated with dissociative anaesthesia
Ketamine
67
What anaesthetic agent is safe to use for sedation in the less monitored environment and why
Ketamine - maintains airway protection
68
What is suxamethonium metabolised by
Plasma cholinesterase
69
List the non-depolarising muscle relaxants
- Altracurium
- Vecuronium
- Pancuronium
70
Why does altracurium cause facial flushing, tachycardia, and hypotension
Causes generalised histamine release on administration
71
What is the reversal agent for altracurium, vecuronium, and pancuronium
Neostigmine
72
What is the incidence of malignant hyperthermia
1 in 15000
73
What is the inheritance pattern and gene defect associated with malignant hyperthermia
- Autosomal dominant
| - Defect in gene on chromosome 19 encoding the ryanodine receptor
74
What are the clinical features of malignant hyperthermia
- Hyperpyrexia
| - Muscle rigidity
75
What is the treatment of malignant hyperthermia
Dantrolene - prevents calcium release from the sarcoplasmic reticulum
76
What percentage of total volume does plasma make up
5% (3L)
77
In what physiological state should Hartmann's solution be used cautiously and why
Alkalosis - as lactate is metabolised to bicarbonate
78
Where is a tracheostomy inserted
2cm below the cricoid cartilage
79
What is the background radiation rate
2.2msv per year
80
What is the CT scan attributable risk of cancer
1 in 2000
81
What is used to maintain anaesthesia
Inhalational anaesthetics
82
What are the side effects of Halothane
- Causes respiratory depression and CO2 retention
- Negative inotrope
- Mild muscle relaxant
83
Which inhalational anaesthetic should be avoided in epileptics
Enflurane
84
What condition is associated with isoflurane use
Coronary steal syndrome
85
What substance can be used to potentiate the effect of inhalational anaesthetics
Nitrous oxide
86
What are the risks of prolonged exposure to nitrous oxide
Suppresses methionine synthase which leads to myelosuppression and megaloblastic anaemia
87
What are the absolute contraindication to halothane
- History of pyrexia after admission
| - Jaundice
88
What agents are associated with malignant hyperthermia
- Halothane
- Suxamethonium
- Antipsychotics
89
What is the treatment of Torsades de Pointes
IV Magnesium sulphate
90
What should be given to patients 2-3hrs before elective surgery
Carbohydrate-rich drinks
91
In whom do benzodiazepines reduce the incidence of post-operative delirium
Those already taking benzodiazepines
92
What is the postoperative concern in those with aortic stenosis
Cannot increase CO
93
What is the risk of using verapamil in VT
Can cause VF
94
What are the characteristics of stored blood
- High K+
- Low pH
- Decreased 2,3-DPG
- Less factor V and 8
95
Why does hypotension occur under spinal anaesthetic
Splanchnic vasodilatation
