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Phase 3a Emily > Anaesthetics > Flashcards

Anaesthetics Flashcards

(49 cards)

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1
Q

what are the rules on fasting pre-op?

A

6hrs = no food or solids
2 hrs = no clear fluids

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2
Q

What is the purpose of preoxygenation?

A

Patient given a few mins of 100% O2
- provides reserve O2 while insetting tube

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3
Q

What is the triad of anaesthetics?

A
  1. Hypnotics
  2. Muscle relaxation
  3. Analgesia
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4
Q

What are the types of hypnotics?

A
  • propofol
  • sevoflurane
  • ketamine
  • thiopental
  • etomidate
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5
Q

Types of muscle relaxants?

A
  1. depolarising e.g. suxamethonim
  2. non-depolarising e.g. rocuronium
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6
Q

What are the pros and cons of TIVA vs volatile gas?

A

Gas
- bad for environment, greenhouse gases
- more nausea and vomiting
- take longer to wake up and out to sleep
- can cause rigidity first and then floppiness

TIVA
- wake up more immediately
- Less nausea and vomiting

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7
Q

When is a muscle relaxant used?

A
  • to intubate
  • laparotomy
  • big surgeries
    (in paeds spray local on vocal cords instead)
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8
Q

How does a depolarising muscle relaxant work? example?

A
  1. mimics acetylcholine and binds to nicotine Ash receptors
  2. causes initial depolarisation of the muscle membrane -> muscle fasciculations
  3. not broken down by acetylcholinesterase –> stays bound –> receptor stay depolarised -> muscle cannot depolarise -> lead to flaccid paralysis

example: suxamethonium

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9
Q

When is suxamethonium used and risks?

A

in emergencies = quick onset and short duration

Risks:
- hyperkalemia
- malignant hyperthermia
- bradycardia
- fasciculations
- increased intraocular pressure
- suxamethonium apnoea

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10
Q

What is malignant hyperthermia?

A

genetic disorder of skeletal muscle that causes massive, uncontrolled release of calcium from the sarcoplasmic reticulum in muscle cells.
leads to:
- sustained muscle contraction
- hyper metabolism
- massive heat production
- cell damage and death

cause
- due to RYR1 gene

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11
Q

What are the triggers of malignant hyperthermia?

A
  • suxamethonium
  • volatile anaesthetic agents e.g. halothane, sevoflurane, isoflurane
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12
Q

What are the clinical features of malignant hyperthermia?

A

Usually starts within minutes of induction, but can be delayed:

Rapid rise in end-tidal CO₂ (early sign)

Muscle rigidity (especially masseter spasm)

Hyperthermia (can exceed 41°C/105.8°F)

Tachycardia, arrhythmias

Acidosis (metabolic and respiratory)

Hyperkalemia

Rhabdomyolysis → myoglobinuria → renal failure

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13
Q

Management: malignant hyperthermia

A
  1. stop triggering agents
  2. administer IV dantrolene
  3. active cooling - ice packs, cold IV fluids
  4. treat complications - acidosis, hyperkalaemia, arrhythmias
  5. supportive care in ICU
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14
Q

Diagnosis + prevention: malignant hyperthermia

A

Definitive diagnosis via muscle biopsy and in vitro contracture test (IVCT)

Genetic testing for RYR1 or CACNA1S mutations

High-risk individuals should wear medical alert tags

Use safe anesthesia protocols (e.g., TIVA – total intravenous anesthesia)

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15
Q

How do non-depolarising muscle relaxants work?

A
  1. competitive antagonist at nicotinic acetylcholine receptors at neuromuscular junction
  2. bind to receptor without activating it, blocking acetylcholine from binding
  3. prevents depolarisation of muscle membrane –> no action potential –> no muscle contraction
  4. result = flaccid paralysis
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16
Q

Types and features of non-depolarising muscle relaxants used?

A
  • rocuronium
  • vecuronium
  • atracurium
  • pancuronium

slower onset and duration varies
- do NOT cause fasciculations
- onset and recovery are slower and more controlled
- cardiovascular side effects

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17
Q

How does reversal for non-depolarising muscle relaxants work?

A

can be reversed with acetylcholinesterase inhibitors e.g. neostigmine
(these increase EACh levels, which outcompete the NDMR at the receptor)

OR with sugammadex = binds directly to drug and inactivates it

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18
Q

What are the emergency anaesthetic drugs?

A
  • suxamethonium = laryngospasm
  • atropine = bradycardia
  • glycopyrronium = bradycardia
  • ephedrine = hypotension
  • metaraminol = hypotension
  • adrenaline = suspected anaphylaxis
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19
Q

What local anaesthetic toxicity?

A
  • excessive dose or accidental intravascular injection of local anaesthetic
  • slow metabolic or accumulation in patients with liver issues
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20
Q

Presentation: local anaesthetic toxicity

Study These Flashcards
A

CNS toxicity
early sx
- perioral numbness
- metallic taste
- tinnitus
- light headed
- visual disturbances

late
- tremors, muscle twitching
- seizures
- CNS depression

Cardiovascular toxicity
- myocardial depression
- bradycardia
- conduction blocks
- ventricular arrhythmias
- cardiac arrest

21
Q

Management: local anaesthetic toxicity

Study These Flashcards
A

1.Stop injecting LA immediately

  1. Call for help & secure ABCs
  2. Give 100% oxygen, maintain airway
  3. Control seizures:
    - Benzodiazepines (e.g., midazolam)
    - Avoid large doses of propofol if cardiovascular collapse is suspected
  4. 20% intralipid emulsion therapy
    - initial = 1.5ml/kg IV over 1 min
    - then = 0.25ml/kg/min for least 10 mins
22
Q

How can you prevent local anaesthetic toxicity?

Study These Flashcards
A

Use lowest effective dose

Aspirate before injecting

Inject slowly with frequent aspiration

Use ultrasound guidance when available

Be especially cautious with bupivacaine and ropivacaine

23
Q

what is the process of emergence from anaesthetic?

Study These Flashcards
A
  1. check muscle relaxant has worn off
    - ulnar nerve = thumb twitch
    - facial nevre = obicularis oculi
    (need 4 twitches)
  2. Hypnotic agent stopped
  3. extubated when breathing themselves
24
Q

MOA of local anaesthetics

Study These Flashcards
A

Inhibit excitation of nerve endings
- reversibly bind to and inactivate sodium channels
- stop influx of sodium through channels so NO depolarisation of nerve cell membranes
- no depolarisation = loss of sensation

25
Endotracheal tube vs LMA
ETT - difficult airway - definitive airway - reflux - long surgery/head hard to access LMA - short surgery - no other risk factors - elective
26
What are the difficulties of OSA in anaesthetics?
- hard to do face to mask control - struggle to get off ventilator after surgery - more likely to have diabetes (airway collapses when lying down) would be better to do a spinal
27
When is a spinal used?
- lower body surgery - high risk medical patients e.g. resp disease, cardio problems, OSA, difficult airway - desire to avoid GA - frail - early mobilisation - good post-op analgesia
28
What is the action of nerve block?
action - nerve block involves injection fo local anaesthetic around a specific nerve: -> block nerve signal transmission -> prevent pain sensation inhibits sodium channels in nerve, stopping depolarisation and conduction
29
Why use a nerve block?
1. anaesthesia for surgery 2. post-op pain control = lasts up to 14 hrs whereas a spinal wears off after 2-3 hrs 3. chronic pain management e.g. sciatic, trigeminal neuralgia, cancer pain 4. diagnostic use - to help identify source of pain by temporarily blocking nerve signals
30
What are the steroid rules for surgery?
Who needs steroid cover: - prednisolone >5mg/day for >3weeks within past year - high dose steroids (>20mg/day) for shorter periods - any dose of steroids with signs of adrenal suppression -
31
What are the steroid cover doses?
minor surgery - continue usual daily dose moderate surgery - usual morning dose + 50mg hydrocortisone IV at induction, then 25mg IV every 8hrs for 24hrs major - usual does + 100mg IV at induction, then 50mg IV every 8hrs for 24-72hrs
32
What are the pros and cons of ketamine in anaesthetics?
pros - cardio stable - analgesia - sedation - anaesthesia - quick acting = used in resus and sepsis - does not stop airway reflexes (give opioid with it to stop gag reflex) cons - hallucinations
33
Who needs a sliding insulin scale?
- poorly controlled diabetes - missing more than 1 meal - concern for preoperative hyperglycaemia or ketosis - on high dose insulin or multiple diabetes medications - emergency surgery - type 1 diabetes usually
34
What are the rules for diabetes patients?
- put them on the list first in the morning = to avoid increased fasting time - take metformin still on day of surgery - restart all medication once eating and drinking normally
35
What does a VRII consist of?
- IV soluble insulin = 0.5-1unit/hour (short acting, actarapid insulin) - IV glucose = 10% dextrose at 125ml/hr (keep glucose between 6-10) - IV potassium = monitor closely, as insulin drives potassium into cells
36
Why might blood sugar be elevated in an unwell surgical patient?
Glucose often elevated due to stress response, to provide extra energy. This leads to increased blood glucose levels. 1. Body releases stress hormones = cortisol, Adrenaline, glucagon 2. Increase blood glucose by stimulating glycogenolysis and gluconeogenesis 3. More glucose released into bloodstream to fuel the brain and muscles
37
what problems may hyperglycaemia cause in a surgical patient?
High glucose can cause: - Infections - Delayed wound healing = impaired collagen synthesis - Increased risk of DKA - Cardiovascular stress - Dehydration – due to peeing out sugar
38
What medications are you interested in pre-op assessment?
- Anti-hyperglycaemia and insulin - Anti-hypertensive - Anticoagulants - Immunosuppressants - Steroids - Oral contraceptives = Sugammadex makes contraceptive ineffective
39
Wha is the mallampati score?
tool used to predict difficulty of intubation class I = Soft palate, fauces, uvula, tonsillar pillars Easy II = Soft palate, fauces, part of uvula, Usually easy III = Soft palate, base of uvula only, Possibly difficult IV = Only hard palate visible Likely difficult (difficult airway)
40
What is the ASA classification system?
the higher the number, the greater the risk of complications under anaesthesia ASA I - Normal healthy patient - Non-smoker, minimal alcohol, fit and well ASA II - Mild systemic disease, no functional limitation -Well-controlled asthma, diabetes, or hypertension ASA III -Severe systemic disease, some functional limitation -COPD, stable angina, poorly controlled diabetes ASA IV - Severe systemic disease that is a constant threat to life Recent MI, unstable angina, ongoing sepsis ASA V - Moribund patient not expected to survive without the operation - Ruptured AAA, massive trauma, multiorgan failure ASA VI - Brain-dead patient undergoing organ donation - Organ donor
41
Which patients are at higher risk of delayed gastric emptying?
- diabetic - pregnant - acute abdomen
42
What are the benefits and risk of an epidural?
pros - good pain relief, reduced opioid use - improved post-op mobility - better lung function - enhanced gut function = less post-op ileus - increased coughing = reduce chest infections cons - hypotension - motor block - urianry retention infection - epidrtual haematoma = paralysis - post-dural puncture headache = frontal, worse when sitting up as CSF leaks out - abscesses - high block = C345 diaphragm, T3 cardio complex
43
What other benefits of epidural anaesthesia are there for the surgeon and anaesthetist
Surgeon - Better intraoperative stability = less BP fluctuations, less bleeding - Reduced ontraoperative opioid use - Less post op ileus - Reduced VT risk Anaesthetist - Better control of post-op pain - Less requirement for systemic analgesia - Less risk of post-op resp depression
44
epidural vs spinal
Epidural - Can top up through catheter - Reduce stress response in surgery - Run infusion - Subtle block with analgesia effect without motor block Spinal - Will block motor nerves more - Work quicker - will only last for 2-3 hrs - stronger block to use in surgery e.g. for knee/hip replacements
45
What are the contraindications to an epidural?
- Patient refusal - Spinal deformities - Raised intracranial pressure  risk of brain herniation - Anticoagulation - Sepsis - Severe aortic stenosis = fixed output so can’t increase cardiac output so severe hypotension - Significant hypovolaemia or shock - Allergy - Neurological disease e.g. MS, peripheral neuropathy
46
How should anticoagulation be managed in the preoperative period?
Apixaban – stopped 48-72 hrs before surgery Can use LMWH for bridging if needed – start 6 hrs postop (tinzaparin) Then restart apixaban 48 hrs post op if no bleeding risk Apixaban reversal – adenexa-alpha (only warranted if emergency, otherwise can give blood plasma)
47
AT what Hb level would you need to transfuse someone?
Hb <7g/dl = transfuse Hb 7-8 g/dL = consider transfusion if symptomatic or high risk But due to IHD = minimize risk of ischaemia of reduced supply Hb <8 = transfusion 8 -10 = if symptomatic (chest pain, tachycardia)
48
What are the types of shock?
- Cardiogenic = MI, CO reduced  systemic vascular resistance increases (vasoconstriction) - Hypovolemic = increased CO  SVR increase and decrease CVP - Distributive = anaphylaxis, addisons. CO high  SVR low and CVP low - Obstructive = PE, tamponade, SVC in cancer patients. High CO = high SVR + high CVP
49

Phase 3a Emily (9 decks)

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