Anaesthetics / Critical Care Flashcards

1
Q

what does a pre-op assessment involve?

A

Hx
- PC - op, indication
- previous anaesthetics - method, problems, cx, malignant hyperthermia, sux apnoea
- DHx, allergies
- PMHx - all systems, quantify severity
- FHx
- SHx - drink, smoke, ADL, living situation

Examination
- CV, resp + abdo
- ECG, ECHO, CPET
- baseline bloods - FBC, U/E, LFTs, clotting, G+S

Airway assessment
- mouth opening
- jaw subluxation
- C-spine extension
- mallampati
- dentition

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2
Q

food and drinks rules before surgery?

A
  • clear fluids >2hrs
  • foods >6hrs
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3
Q

diabetes for operations

A
  • on insulin with good glycaemic control (HbA1c<69) - if minor procedure - just adjust usual insulin regimen
  • surgery with long fast / 1+ missed meal / poorly controlled DM - VRIII
  • VRIII with OHAs if 1+ meal missed, poor glycaemic control, or risk of renal injury
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4
Q

rules for emergency cases needing op?

A

stabilise, resus, consider abx/blood
consent + inform relatives

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5
Q

special considerations for thyroid surgery?

A

Thyroid surgery – vocal cord check.
Parathyroid surgery – consider methylene blue to identify gland.
Thyrotoxicosis – lugols iodine/ medical therapy.

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6
Q

special considerations for SNB, thoracic duct surgery, pheochromocytoma surgery and colorectal cases

A

Sentinel node biopsy – radioactive marker/ patent blue dye.

Surgery involving the thoracic duct – consider administration of cream.

Pheochromocytoma surgery – will need alpha and beta blockade.

Colorectal cases – bowel preparation (especially left sided surgery)

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7
Q

steroid considerations for op?

A
  • for pts on long term steroids
  • major surgery - hydrocortisone with pre-med then 6-8hrly for 3d
  • hydrocortisone for 24hr
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8
Q

Drugs to stop pre-op?

A

Insulin
- Sliding scale for major surgery
- Reduce bedtime dose + omit morning dose in minor surgery

Lithium
- Day before major surgery

Anticoagulants/platelets
- Warfarin 5d before with LMWH bridging (give dose vit K if INR>1.5 on day of)
- Antiplatelets 5-7d before
- Aspirin variable

cOCP/HRT
- 4wks before major, restart 2wks after

K sparing diuretics
- Day of surgery

Oral hypoglycaemics
- Metformin 48hrs before, restart 4d later when renal function ok

Perindopril / ACEi
- 24hrs before

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9
Q

triad of general anaesthesia + drug examples for each?

A

Analgesia
- fentanyl
- alfentanil
- remifentanil
- morphine

Hypnosis
IV
- propofol
- ketamine
- sodium thiopentone
- etomidate
Inhaled
- sevofluorane, desflurane, isoflurane
- NO

Muscle relaxation - block NMJ (ACh blocked)
Depolarising
- suxamethonium
Non-depolarising
- rocuronium
- atracurium
Reversal
- neostigmine (AChE inhibitor)
- sugammadex - non-depolarising

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10
Q

antiemetic options post op

A
  • ondansetron - serotonin antagonist - beware long QT
  • dexamethasone - corticosteroid - caution diabetics/immuno
  • cyclizine - H1 receptor antagonist - caution HF/elderly
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11
Q

risks of GA?

A
  • Sore throat
  • Post-operative N+V
  • Accidental awareness
  • Aspiration
  • Dental injury
  • Anaphylaxis
  • CV events - MI, stroke, arrhythmias
  • Malignant hyperthermia
  • Death
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12
Q

Propofol (hypnotic)

A
  • GABA receptor agonist
  • rapid onset, burns on IV injection, rapidly metabolised, anti-emetic, BP drops
  • TIVA
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13
Q

Ketamine (hypnotic)

A
  • NMDA receptor antagonist
  • analgesia, may dissociate pt (nightmares/hallucinations), BP stable
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14
Q

Sodium thiopentone (hypnotic)

A
  • barbiturate - potentiates GABA
  • rapid onset, BP drops, unstable for maintenance
  • lipid soluble
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15
Q

Etomidate (hypnotic)

A
  • potentiates GABA
  • little CV instability, may suppress adrenals
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16
Q

Suxamethonium (relaxant)

A
  • depolarising - binds to AChR - persistent depolarisation at NMJ
  • fast onset, muscular contraction before paralysis
  • adverse effects - hyperkalaemia, malignant HTN
  • CI - AACG
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17
Q

Atracurium (relaxant)

A
  • non-depolarising - competitive antagonist of AChR
  • lasts 30-45mins
  • histamine release on administration -> facial flushing, tachycardia, hypotension
  • broken down in tissues
  • neostigmine to reverse
18
Q

Vecuronium (relaxant)

A
  • non-depolarising, lasts 30-40mins
  • degraded by liver/kidney
  • reverse with neostigmine
19
Q

Pancuronium (relaxant)

A
  • pancuronium
  • 2-3min onset, 2hr duration
  • partially reverse with neostigmine
20
Q

Rocuronium (relaxant)

A
  • non-depolarising
  • sugammadex reversal
21
Q

Lidocaine

A
  • amide
  • blocks Na channels in axon - prevents depolarisation
  • hepatic metabolism, protein bound, renally excreted
  • intralipid if OD
  • max dose - 3mg/kg plain, 7mg/kg + adrenaline
22
Q

Bupivacaine

A
  • binds to intracellular Na channels, blocks Na influx, prevents depolarisation
  • longer duration than lidocaine
  • cardiotoxic
  • levobupivacaine - less cardiotoxic/vasodilation
  • max dose - plain 2mg/kg, +adrenaline 2mg/kg
23
Q

Prilocaine

A
  • Less cardiotoxic - used for Biers block / regional blocks
  • max dose plain 6mg/kg, adrenaline 9mg/kg
24
Q

Regional anaesthesia

A
  • Numb specific nerve
  • Use US to inject
  • May use in combination with GA to reduce pain
25
Q

Spinal anaesthetic

A
  • Aka central neuraxial anaesthesia
  • For c-sections, NOF repair, TURP
  • LA injected into CSF, within subarachnoid space
  • Needle inserted around L3/4 or L4/5
  • Check it works with cold spray
26
Q

Epidural anaesthesia + possible adverse effects

A
  • For analgesia
  • Most commonly during labour, or post-operatively after laparotomy
  • Insert catheter into epidural space, outside dura mater
  • Levobupivacaine +/- fentanyl inserted – diffuses into tissues + nerve roots

Adverse effects
- Headache if dura is punctured – CSF leaks from dural tap
- Hypotension
- Motor weakness in legs - urgent anaesthetic review needed – catheter may be sited in subarachnoid space
- Nerve damage
- Infection, meningitis
- Haematoma – may cause spinal cord compression
- Prolonged second stage labour
- Increased probability of instrumental delivery

27
Q

tracheostomy + indications

A
  • Hole in neck to access trachea
  • Held in place with stiches or soft tie (trach tie)

Indications
- Resp failure with requirement for long term ventilation
- Prolonged weaning from ventilation (eg ICU pt weak after illness)
- Upper airway obstruction (tumour, head/neck surgery)
- Mx of resp secretions – pts with paralysis
- Reduce risk of aspiration (eg pts wth unsafe swallow / absent cough reflex)

28
Q

Difficult airway stepwise plan

A
  • Plan A - laryngoscopy with tracheal intubation
  • Plan B - i-gel
  • Plan C - face mask ventilation and wake pt up
  • Plan D - cricothyroidotomy
29
Q

ASA classifications

A

ASA I – normal, health patient
- Eg non-smoker, no disease

ASA II – mild systemic disease
- Mild disease, no functional limitations – eg current smoker, pregnancy, controlled DM/HTN

ASA III – severe systemic disease
- Functional limitations – eg poorly controlled DM, COPD, BMI>40, active hepatitis, >3mo ago of MI/CVA

ASA IV – severe systemic disease that is constant threat to life
- <3mo hx of MI/CVA, cardiac ischaemia, valve dysfunction, HF with reduced ejection fraction

ASA V – moribund patient not expected to survive without operation
- Eg ruptured AAA, massive trauma, intracranial bleed, ischaemic bowel

ASA VI – brain-dead patient, organs being removed for donor purposes

30
Q

malignant hyperthermia- definition, Px, Ix and Mx

A
  • hypermetabolic response to anaesthesia
  • from excessive release of Ca from SR in skeletal muscle
  • halothene, suxamethonium, antipsychotics
  • autosomal dominant risk

Px
- hyperthermia
- increased CO2 production
- tachycardia
- muscle rigidity
- acidosis
- hyperkalaemia

Ix
- raised CK
- contracture tests with halothane + caffeine

Mx
- dantrolene - prevents Ca release from SR

31
Q

IV access options

A

Peripheral venous cannula
- no inotropes / irritant drugs - eg TPN

Central line
- IJ, subclavian, femoral
- vas cath - 2/3 lumens
- portacath - port under skin, connects to subclavian vein

IO
- via marrow cavity

Tunnellled lines
- Gsoshong / Hickman lines

Peripherally inserted central cannula (PICC)
- insert peripherally, lumen ends centrally
- pulmonary artery catheter - Swan-Ganz

32
Q

Nutrition in surgical patients

A

Oral
- easiest
- CI’d after certain procedures

NG
- via fine bore NG tube
- Cx - aspiration of feed, misplaced tube
- eg impaired swallow
- CI’d head injury

Nasojejunal
- avoids problems of feed pooling in stomach + aspiration risk
- insertion more complicated

Feeding jejunostomy
- surgically sited feeding tube
- can be long term
- low asp risk

Percutaneous endoscopic gastrostomy (PEG)
- Combined endoscopic and percutaneous tube insertion
- must be able to tolerate OGD

TPN
- where enteral feed CI’d
- need central line - phlebitis risk
- long term use - fatty liver, deranged LFTs

33
Q

post op pyrexia?

A

Early causes (0-5d)
- Blood transfusion
- Cellulitis
- UTI
- Physiological systemic inflammatory reaction (usually within day)
- Pulmonary atelectasis

Late causes (>5d)
- VTE
- Pneumonia
- Wound infection
- Anastomotic leak

4 Ws – wind, water, wound, what did we do (iatrogenic)

34
Q

Cx of periop hypothermia

A
  • Coagulopathy, increased blood loss
  • Prolonged anaesthetic recovery
  • Reduced wound healing - local vasoconstriction
  • Infection - poor site healing, reduced no of immune cells
  • Shivering - increased metabolic rate, myocardial ischaemia in some populations
35
Q

VTE prophylaxis

A

RFs
- reduced mobility, ortho surgery, >90mins surgery, acute surgical admission, cancer/chemo, >60yo, thrombophilia, BMI>35, comorbidities, critical care admission, HRT/cOCP, varicose veins, pregnant, <6wks post partum

Mx
- compression stockings
- intermittent pneumatic compression device
- fondaparinux / enoxaparin / heparin / doac
- mobilise asap after surgery, ensure hydrated

36
Q

wound healing steps

A
  • haemostasis
  • inflammation
  • regeneration
  • remodelling
37
Q

scar types

A

Hypertrophic scars
- excessive collagen

Keloid scars
- excessive collagen, extends beyond scar

Drugs which impair wound healing
- NSAIDs, steroids, immuno, anti-neoplastic

Closure
- delayed primary - leave open, close before granulation tissue forms
- secondary - allow granulation tissue to form

38
Q

what are the 3 levels of care?

A

Level 1 - general acute ward
Level 2 - HDU
Level 3 - ICU - needing organ support

39
Q

Scoring systems to predict mortality at ICU admission

A

APACHE - acute physiology and chronic health evaluation
SAPS - simplified acute physiology score
MPM - mortality prediction model

40
Q

ICU cx

A

-ventilator-associated lung injury - volutrauma, barotrauma….
- VAP
- catheter-related bloodstream infections
- catheter-associated UTIs
- mucosal disease
- deliriun
- VTE
- critical illness myopathy / neuropathy