Anaesthetics Flashcards
(134 cards)
1
Q
Name 5 common examples of procedures that require local anaesthetic
A
Skin Suturing after skin laceration
Minor surgery to remove skin lesions
Hand surgery (Carpal tunnel syndrome)
Performing Lumbar Puncture
Inserting a central line
2
Q
Name 4 local anaesthetics
A
Lidocaine
Cocaine
Bupivacaine
Prilocaine
3
Q
What typically causes local anaesthetic toxicity? (2)
A
Inadvertent venous or arterial injection
High dose of ingested or topically administered local anaesthetic-containing preperations.
4
Q
Name 4 factors that contribute to the concentration of local anaesthetic that can enter systemic circulation
A
Total Dose
Rate of administration
Route and location of administration
Presence or not of adrenaline in preparation
5
Q
What is the typical half life of most local anaesthetic preparations? (2)
A
2 hours
(Bupivacaine 5 hours)
6
Q
Name 5 early clinical features of local anaesthetic toxicity
A
Tinnitus
Difficulty with visual focus
Dizziness/lightheadedness
Anxiety/Agitation/Confusion
Perioral and/or tongue numbness
7
Q
Name 4 severe features of local anaesthetic toxicity
A
CNS: Seizures/Coma
Cardio: Bradycardia, Hypotension, Conduction blocks, Ventricular dysrythmias
Resp: Respiratory depression, apnoea
Methaemoglobinaemia: Blue mucous membranes progressing to CNS.
8
Q
Name 4 investigations used for local anaesthetic toxicity
A
UEC (Urea, Electrolytes and Creatinine)
ABG
Methaemoglobin concentration
ECG
9
Q
What may an ECG show in local anaesthetic toxicity?
A
Evidence of Sodium Channel Blockade;
Prolonged PR
Prolonged QRS
Large terminal R waves in aVR
10
Q
How is methaemoglobinaemia treated? (local anaesthetic toxicity)
A
Methylene Blue
11
Q
How are ventricular dysrythmias treated? (local anaesthetic toxicity)
A
Sodium Bicarbonate
12
Q
What is the antidote for local anaesthetic toxicity?
A
IV Lipid Emulsion (intralipid 20%)
13
Q
Name 4 potential adverse effects of lipid emulsion infusion
A
Anaphylaxis
Pancreatitis
Venous Embolism
Pulmonary hypertension
14
Q
Give one use for cocaine as an anaesthetic
A
ENT Surgery
15
Q
What ion channel do anaesthetics block? What does this prevent?
A
Blocks Sodium Channels (and thus sodium influx into cells)
Prevents depolarization (and this stops action potential propagation)
16
Q
What local anaesthetic is used at the conclusion of surgical procedures and why?
A
Bupivacaine
Has a longer half life (5 hours) so has a longer analgesic effect
17
Q
Give one adverse effect of bupivacaine
A
Cardiotoxic
18
Q
What are the doses of Lignocaine, Bupivacaine and Prilocaine WITHOUT adrenaline?
A
Lignocaine - 3mg/Kg
Bupivacaine - 2mg/Kg
Prilocaine - 6mg/Kg
19
Q
What are the doses of Lignocaine, Bupivacaine and Prilocaine WITH adrenaline?
A
Lignocaine - 7mg/Kg
Bupivacaine - 2mg/Kg
Prilocaine - 9mg/Kg
20
Q
What the effect does adrenaline have on local anaesthetics? (2)
A
Prolongs the duration of action at the site of injection.
Also has a vasoconstrictive effect, so decreases bleeding
21
Q
Give 2 contraindications for adrenaline use (local anaesthetics) (2)
A
In patients taking MAOIs (monoamine oxidase inhibitors - Isocarboxazid, Selegiline)
In patients taking Tricyclic antidepressants (Amitriptyline, Imipramine)
22
Q
Describe general anaesthesia
A
Making a patient unconscious
23
Q
Describe regional anaesthesia
A
Blocking feeling to an isolated area of the body (e.g a limb)
24
Q
What is used to control a patient’s breathing when under GA?
A
Intubation or Supraglottic Airway Device (SAD) + Ventillaiton
25
Why is fasting important for patients undergoing GA?
Empty stomach reduces the risk of stomach contents refluxing into the oropharynx (throat) and being aspirated into the trachea.
26
What can happen if gastric contents is aspirated into the lungs?
Pneumonitis (inflammation of lung tissue)
27
When is the risk of aspiration highest during GA?
Before and during intubation, and when they are being extubated.
28
Describe the pattern of fasting for an operation under GA (2)
6 hours no food or feeds before an operation
2 hours of no clear fluids (fully nil by mouth)
29
What is preoxygenation and why is it important? (2)
Period (before being put under GA) where the patient receives several minutes of 100% oxygen.
Gives patient reserve oxygen for the period between when they lose consciousness and are successfully intubated and ventilated.
30
Name 3 medications which may be given before a patient is put under GA. Describe why they are given.
Benzodiazepines (Midazolam) - Relaxes muscles and reduces anxiety
Opiates (fentanyl/afentanyl) - To reduce pain and reduce hypertensive response to laryngoscope
Alpha-2-adrenergic agonists (clonidine) - Help with sedation and pain
31
What is used to gain control of the airway during emergency operations?
Rapid Sequence Induction/Intubation
32
What is the biggest concern of Rapid Sequence Induction/Intubation? What precautions are put in place to prevent this? (2)
Aspiration of stomach contents into lungs.
Position bed upright to reduce reflux up the oesophagus.
Cricoid pressure (pressing on cricoid cartilage in the neck) to compress the oesophagus and prevent refux.
33
What is the triad of general anaesthesia?
Hypnosis
Muscle relaxation
Analgesia
34
What is the purpose of hypnotic agents in GA? How can they be given?
Hypnotic agents make the patient unconscious. Can be given IV or Inhaled.
35
Name 2 IV Hypnotic Agents
Propofol (most common - Used to Induce GA)
Ketamine
36
Name 2 Inhaled Hypnotic Agents
Sevoflurane (most common- Used to maintain GA)
Nitrous Oxide
37
Describe the pattern of use for IV and Inhaled hypnotic agents.
IV medication is used as an Induction Agent (to induce unconsciousness)
Inhaled medications are used to Maintain GA during the operation
38
What is the purpose of muscle relaxants in GA? How do they work?
Purpose - To relax and paralyse muscle, making intubation and surgery easier
MOA - Block the action of Acetyl Choline at the NMJ.
39
Name 2 categories (and drugs) of muscle relaxants used in GA
Depolarising (Suxamethonium)
Non-depolarising (rocuronium and atracurium)
40
What can be used to reverse the effects of neuromuscular blocking medications (muscle relaxants)?
Cholinesterase inhibitors (neostigmine)
41
What is used to reverse the effects of depolarising muscle relaxants, such as rocuronium and vecuronium?
Sugammadex
42
Give 2 adverse effects of volatile liquid anaesthetics (such as isoflurane, desflurane and sevoflurane)
Myocardial depression
Malignant Hyperthermia
43
What is the MOA of Propofol?
Potentiates GABAa
44
What is the MOA of Ketamine?
Blocks NMDA receptors
45
Why is Ketamine useful in trauma?
As it doesn't drop blood pressure
46
Name 4 drugs used as analgesia in GA
Opiates;
Fentanyl
Alfentanil
Remifentanil
Morphine
47
Name 3 antiemetics used in GA and their state their MOA
Ondansetron (5HT3 receptor antagonist)
Dexamethasone (corticosteroid)
Cyclazine (Histamine H1 receptor antagonist)
48
Where may ondansetron be contraindicated?
In patients at risk of Prolonged QT interval
49
Where may Dexamethasone be used with caution?
In diabetic or immunocompromised patients
50
Where may Cyclizine be used with caution?
In Heart Failure or Elderly Patients
51
Describe Emergence and how it is tested (2)
Emergence describes the process of waking a patient from GA.
Can be tested by:
Ulnar Nerve Stimulation (Watch thumb twitch)
Facial Nerve Stimulation (watch Orbiculares Oculi muscle twitch)
52
What is the train-of-four (TOF) stimulation?
Describes when a nerve is stimulated 4 times;
If the muscle responses remain strong, this indicates the muscle relaxant has worn off.
If the muscle responses get weaker with additional stimulation, this indicates the muscle relaxant hasn't fully worn off.
53
Give 2 common adverse effects of GA
Sore throat
Post operative nausea and vomiting
54
Give 5 significant risks of GA
Accidental awareness (waking during the anaesthetic)
Aspiration
Dental injury (2nd to laryngoscope used for intubation)
Anaphylaxis
Malignant hyperthermia (rare)
55
Describe malignant hyperthermia. What is it associated with?
Potentially fatal hypermetabilic response to anaesthesia
Associated with;
Volatile anaesthetics (isoflurane, sevoflurane and desflurane)
Suxamethonium
56
Give 6 symptoms of malignant hyperthermia
Increased Body Temperature (hyperthermia)
Increased Carbon Dioxide Production
Tachycardia
Muscle Rigidity
Acidosis
Hyperkalaemia
57
How is malignant hyperthermia treated? What is the MOA?
Dantrolene
Depresses excitation-contraction coupling in skeletal muscle. Binds to ryanodine receptor 1 and decreases intracellular calcium concentration.
(ryanodine receptors mediate the release of calcium from the sarcoplasmic reticulum)
58
Name 5 muscle relaxants
Suxamethonium
Atracurium
Vecuronium
Rocuronium
Pancuronium
59
What can be used to reverse the effects of muscle relaxants (such as Vecuronium)? What is its moa?
Neostigmine (Acetylcholinesterase inhibitor)
60
Give an example of a Depolarizing Muscle Relaxant (1). What is their MOA?
Succinylcholine (Suxamethonium)
Binds to nicotinic acetylcholine receptors resulting in persistent depolarization of the motor end plate
61
Give an example of a Non-Depolarizing Muscle Relaxant (4). What is their MOA?
Tubcurarine
Atracurium
Vecuronium
Pancuronium
Competitive antagonist of nicotinic acetylcholine receptors.
62
What is the muscle relaxant of choice for rapid sequence induction for intubation? And Why?
Succinylcholine (Suxamethonium)
Has the fastest onset and shortest duration of all muscle relaxants.
63
When may suxamethonium be contraindicated? (2)
Penetrating eye injuries
Acute narrow angle glaucoma
(As suxamethonium increases intraocular pressure)
64
Give 1 adverse effect of Non-depolarizing muscle relaxants
Hypotension
65
What agent can be used to reverse the effects of rocuronium or vecuronium (muscle relaxants)? What is its moa?
IV Sugammadex
Selectively binds to rocuronium or vecuronium, preventing them form binding to and antagonising acetyl choline receptors at the NMJ.
66
When should Sugammadex use be avoided?
If creatinine clearance is <30mL/minute
67
Define Minimum Alveolar Concentration (MAC). Why is it important?
The concentration of inhaled anaesthetic within the alveoli at which 50% of people do not move in response to a stimulus.
Important as it provides a correlation between anaesthetic dose and immobility
68
Define Shock
Shock describes an abnormality of the circulatory system that results in reduced organ perfusion and tissue oxygenation.
If untreated, can lead to Multiple Organ Failure and Death.
69
Name 3 types of shock that result from reduced cardiac output
Hypovolemic Shock
Cardiogenic Shock
Obstructive Shock
70
Name 3 types of shock that result from reduced systemic vascular resistance
Septic Shock
Anaphylactic Shock
Neurogenic Shock
71
Give 4 causes of hypovolemic shock
Haemorrhage (internal or external)
Vomiting/Diarrhoea
Burns
Diuresis (excessive urination)
72
Give 4 causes of cardiogenic shock
Myocardial infarction
Myocarditis
Cardiac arrhythmia
Negatively inotropic drug overdose (Beta Blockers/Calcium Channel Blockers)
73
Give 3 causes of obstructive shock
Tension pneumothorax
Massive PE
Cardiac Tamponade
74
How is Blood Pressure Calculated?
BP = Cardiac Output x Systemic Vascular Resistance
75
How is Cardiac Output Calculated?
CO = Heart Rate x Stroke Volume
76
What 3 factors determine stroke volume
Preload
Myocardial contractility
Afterload
77
Define preload
The ventricular wall tension at the end of diastole (reflects the degree of myocardial muscle fibre stretch)
78
Define afterload
Afterload is the ventricular wall tension at the end of systole and is the resistance to anterograde blood flow.
79
How may a shocked patient present on an ABCDE?
A - Airway may be compromised by reduced conscious level
B - Hypoxia and/or Tachypnoea (may have Kussmaul's breathing)
C - Cold, pale peripheries, CRT >3s, Tachycardia, Hypotension, Oliguria, Anuria
D - Confusion, Drowsiness, Unconsciousness
E - Mottled Skin
80
What are the sepsis 6?
Give 3, Take 3
Give: IV Fluid, IV Antibiotics, Oxygen
Take: Blood Cultures, FBC, Lactate `
81
Describe the initial management of shock
ABCDE
Maintain Patent Airway (manoeuvres, adjunctsm ect)
High Flow Oxygen 15L/min to keep sats >94%
Attach ECG, BP monitor and Pulse Oximeter
Obtain IV access (large) and take bloods (Blood gas for pH and Lactate)
IV Fluid Resuscitation (500ml 0.9% Saline STAT)
Urethral catheterisation and fluid balance monitoring (Aim for Urine Output of >0.5ml/kg/hour)
Consider referral to HDU/ICU if BP fails to respond
82
What blood type is universally used for blood transfusions where the blood type is not known?
O negative
83
Give one complication of long-term intubation. How may it present? (3)
Tracheo-oesophageal fistula formation
Presents with productive cough (yellow/brown mucus), chocking after feeds, aspiration pneumonia.
84
Excessive administration of IV 0.9% sodium chloride solution can cause what? (2)
Hyperchloraemic acidosis.
Increased chorice. Kidney removes bicarbonate to maintain electroneutrality > low bicarbonate > acidosis
85
What is the ASA Physical Status Classification System used for?
To assess and communicate a patient's pre-anaesthesia medical co-morbidities.
86
Define ASA 1-6
ASA 1 - A normal healthy patient
ASA 2 - A patient with mild systemic disease (smoker, social alcohol, pregnancy, obesity, controlled DM/HTN)
ASA 3 - A patient with severe systemic disease (poorly controlled HTN, DM, COPD, Obesity - BMI >40 ect)
ASA 4 - A patient with severe systemic disease that is a constant threat to life (recent MI, TIA, sepsis, DIC ect)
ASA 5 - A morbidund patient who is not expected to survive without the operation (ruptured aortic aneurysm, massive trauma ect)
ASA 6 - A declared brain-dead patient whose organs are being removed for donor purposes
87
What ASA category does pregnancy fit under?
ASA 2
88
What is the most appropriate form of intubation used to prevent airway obstruction caused by poor pharyngeal tone (snoring)?
Oropharyngeal tube
89
Where is intraosseous access typically undertaken? When is this preferred?
At the anteromedial aspect of the proximal tibia.
Typically preferred in paediatric practice.
90
Should diabetic patients continue metformin before surgery? Why?
Yes. Continue as normal the day before surgery.
As diabetics have an increased risk of post-operative infection and delayed wound healing due to poor glycaemic control.
91
A 48-year-old lady undergoes a redo thyroidectomy for a multinodular goitre.
24 hours post operatively she develops oculogyric crises and diffuse muscle spasm.
What has occurred and what is the management?
Likely developed hypocalcaemic tetany
Mx - Intravenous Calcium
92
What nerve is most commonly injured during a Posterior Triangle Lymph Node Biopsy?
Accessory Nerve
93
What nerve is most commonly injured during a Posterior Approach to the Hip?
Sciatic
94
What nerve is most commonly injured in the legs in the Lloyd Davies Position?
Common peroneal
95
What surgeries commonly require patients to be in the Lloyd Davies Position?
Colorectal or Pelvic Surgeries
96
What nerve is most commonly injured during Axillary Node Clearance?
Long Thoracic
97
What nerve is most commonly injured during pelvic cancer surgery?
Pelvic autonomic nerves
98
What nerve is most commonly injured during thyroid surgery?
Recurrent Laryngeal Nerve
99
What nerve is most commonly injured during carotid endartectomy?
Hypoglossal nerve
100
What nerve is most commonly injured during Upper Limb Fracture Repairs?
Ulnar and Median Nerves
101
A 22-year-old female is extubated following an uncomplicated surgery. Following, no respiratory effort is made and she is re-intubated and ventilated.
She is monitored in the intensive care unit and all observations are normal.
She is weaned from the ventilator 24 hours later successfully. What complication has occurred?
Suxamethonium Apnoea.
A small subset of the population have an autosomal dominant mutation that leards to a lack of a specific acetylcholinesterase in the plasma which acts to break down suxamethonium (this terminating it's muscle relaxant effects).
Because of this, the effects of suxamethonium are prolonged and the patient needs to be intubated and ventilated for much longer.
102
Why should hypotonic (0.45%) saline use be avoided in paediatric patients?
Increases risk of hyponatraemic encephalopathy (confusion, headache, disturbance of gait)
103
Name an agent which reverses the effects of midazolam. What is it's moa?
Flumazenil.
MOA- Antagonises the effects of benzodiazepines by competitively binding to GABA binding sites.
104
Why do patients require close monitoring after treatment with flumazenil?
Flumazenil - Used to reverse action of benzodiazepines.
Benzo's have a longer half life than flumazenil.
105
Give 1 common post-operative complication of abdominal surgery.
Ileus
106
What symptoms may a patient with an ileus present with?
Fluid and Electrolyte Loss (Before N&V)
Nausea and Vomiting
Abdominal distension
Absolute constipation
107
What is the treatment for an Ileus?
Wide bore Nasogastric Tube
Replacement with IV fluid (until bowel becomes motile again)
108
Define Group and Save and describe its use.
Refers to sending off a sample of a patient's blood to establish their blood group.
The sample is saved in case they require their blood to be matched for a transfusion.
Conducted when there is a small likelihood that the patient will require a blood transfusion.
109
Define Blood Crossmatching and describe its use
Describes taking one or more units of blood from the shelf and assigning it to a patient in case they require a quick blood transfusion.
Conducted when there is a high likelihood that the patient will require a blood transfusion (so the blood is ready to go if required)
110
Name 4 surgeries where only a Group and Save is appropriate
(transfusion unlikely)
Hysterectomy (simple)
Appendicectomy
Laparoscopic cholecystectomy
Thyroidectomy
111
Name 2 surgeries where Crossmatching 2 units of blood may be appropriate.
(transfusion likely)
Salpingectomy for ruptured ectopic pregnancy
Total hip replacement
112
Name 5 surgeries where Crossmatching 4-6 units of blood may be necessary.
(Transfusion definitely required)
Total gastrectomy
Ooophorectomy
Oesophagectomy
Elective AAA repair
Cystectomy
113
What anti-diabetic medications are safe to take during the peri-operative period? (2)
DPP-4 inhibitors (gliptins)
GLP-1 analogues (tides)
114
What anti-diabetic medications should be omitted on the day of surgery. And why? (2)
SGLT-2 Inhibitors (Empagliflozin, Dapagliflozin). (Can increase risk of diabetic ketoacidosis during periods of dehydration or acute illness)
Sulphonylurea (Gliclazide). (Can cause hypoglycaemia in patients in a fasted state)
115
What does Capnography measure? What can it be used to confirm?
Measures the concentration of carbon dioxide in exhaled air.
Can be used to confirm successful tracheal intubation (as CO2 concentrations will increase during exhalation and decrease during inhalation)
116
What is entropy (in the context of anaesthesia?
Entropy monitoring assesses the depth of anaesthesia by assessing a patient's electroencephalogram.
It assesses the effect of anaesthetic drugs.
117
Nasopharyngeal airways are contraindicated when?
Suspected or known Basal Skull Fractures
(Periorbital ecchymosis - Raccoon eyes) and CSF rhinorrhoea are 2 signs of basal skull fracture)
118
What are the 4 stages of wound healing?
Haemostasis
Inflammation (Days 1-5)
Regeneration (Days 7-56)
Remodelling (from 6 weeks to 1 year)
119
Describe the haemostasis phase of wound healing (2)
Occurs minutes to hours following injury
Vasospasm in adjacent vessels, platelet plug forms and generation of a fibrin rich clot occurs.
120
Describe the inflammation phase of wound healing (3)
Occurs on days 1-5 post injury,
Neutrophils migrate into the wound (function impaired in diabetes).
Basic fibroblast growth factor and vascular endothelial growth factor are released.
121
Describe the regeneration phase of wound healing (4).
Occurs on days 7-56 post injury.
Platelet derived growth factor and transformation growth factors stimulate fibroblasts and epithelial cells
Fibroblasts produce a collagen network
Angiogenesis occurs and the wound resembles granulation tissue.
122
Describe the remodelling phase of wound healing.
Occurs from 6 weeks to 1 year (longest phase)
Fibroblasts become differentiated (myofibroblasts) and these facilitate wound contraction.
Collagen fibres are remodelled
Microvessels regress leaving a pale scar.
123
Describe hypertrophic scars
Scars with excessive amounts of collagen.
Tissue is CONFINED to the extent of the wound itself
124
Describe Keloid Scar
Similar to hypertrophic, where excessive amounts of collagen are within the scar.
Keloid scars however PASS BEYOND the boundaries of the original injury.
125
Name 4 drug classes which impair wound healing
NSAIDs
Steroids
Immunosuppressive agents
Anti neoplastic drugs
126
What 3 modalities is GCS split into
Eye Opening
Verbal Response
Motor Response
127
Describe eye opening criteria in GCS
E4 - Spontaneously
E3 - To Voice
E2 - To Pain
E1 - None
128
Describe verbal response criteria for GCS
V5 - Conversation
V4 - Confused
V3 - Words
V2 - Sounds
V1 - None
129
Describe Motor Response criteria for GCS
M6 - Obeys commands
M5 - Localises
M4 - Withdraws
M3 - Flexes
M2 - Extends
M1 - None
130
Use GCS to give 2 indications for CT scan in Adults
GCS <13 initially
GCS <15 at 2 hours post injury
131
What is the recommended neuro obs frequency? (4)
Half hourly until GCS = 15
The half hourly for 2 hours
Then hourly for 4 hours
Then 2-hourly
132
What can contribute to the development of a post-operative ileus? What blood test is it important to do to investigate this?
Deranged electrolytes (Potassium, Magnesium and Phosphate)
U&Es
133
What is the recommended VTE prophylaxis for patients undergoing elective hip replacements?
TED Stockings + Dalteparin Sodium started at least 6 hours post-operation
134
When (and why) is ketamine preferred over propofol as an induction agent for anaesthesia?
In Trauma.
As Ketamine doesn't cause a drop in blood pressure.
