Perioperative Pharmacology Flashcards
What is the ASA grading for patients?
American Society Anesthesiologists, 1963
Grade 1 - normal healthy patient
Grade 2 - patient with mild systemic disease
Grade 3 - patient with severe systemic disease
Grade 4 - patient with severe systemic disease, constant threat to life
MORE ?
What are some examples of pre-anaesthesia problems?
Resus needed
High risk - older age, chronic disease e.g. malignancy, COPD etc
Renal impairment
‘Full stomach’/not starved
What is pre-optimisation?
Possible admission to HDU (but mostly just anaesthetic bay) for admission of:
Invasive BP monitoring
Urinary catheter
Central venous access
Inotropic support - increase BP to counteract post-anaesthetic admission BP drop
Cardiac output monitoring
Broad aim is to maximise oxygen delivery peri-operatively to supra-normal levels
Surgery school/Fit-4-surgery:
A different form of pre-optimisation for elective surgeries - people getting fitter, stopping smoking, losing weight etc before having surgery
What is premedication?
Not used as much/if at all anymore as hasnt found to work majorly
Analgesia
Sedatives
Antiemetics
Antacids/PPIs - these are the most likely to be used currently as pre-op meds
What pre-operative drugs should be omitted for elective surgeries?
ACE inhibitors "-prils" - 24-72hrs ARB's "sartans" - 24-72hrs Anti-TNF - 2wks Platelet inhibitors - aspirin, clopidogrel, prasurgel - 7-10days DOACs - 3-4days
When should you not use NSAIDs?
REDO WHOLE CARD ACCORDING TO BNF
If known or high risk suspicion of gastric ulceration
If increased risk of intraoperative bleeding
If known asthma
If significant renal impairment - can cuase renal failure if given during blood loss or hypotension; precipitate fluid retention; increased risk of hyperkalaemia
Contraindicated
Renal impairment
Hyperkalaemia
Cautions
What are the methods of induction?
Propofol:
Most common
IV
Also ketamine - but used less frequently
What are the methods of maintenance?
Inhalational - fluorinated hydrocarbons:
Sevoflurane
Desfluorane - rapid recovery (but only 5mins earlier extubation) (especially in the obese), very very high global warming potential
Isoflupane (? used less)
Propofol - IV driver (total intravenous anaesthesia - TIVA)
What are some theories behind why general anaesthesia works?
???
What is a spinal? How does it work?
Acts on reticular activating system
What drugs are used for muscle relaxation?
Result in muscle relaxation + importantly, paralysis (therefore will not continue breathing? unlike the relaxation effects of propofol)
Depolarising:
Suxamethonium - non-competitive, acts at NMJ, muscle fibre depolarises and contract, seen as widespread fasciculations as soon as drug spreads through system (often starts with peri-oral and periorbital) - broken down by acetylcholinesterase ?? rapid onset-short duration-rapid offset
Non-depolarising/competitive:
Rocuronium, Atracurium
Takes longer to build up - 3-4 mins
Wears off after 20-40 mins - as equilibrium swings back towards ACh occupying the nicotinic receptors on muscle fibres
what is rapid sequence induction?
Oxygen Propofol Suxamethonium cricoid pressure inserction of ariway ????
What drug is given to reverse a neuromuscular block?
Sugammadex
Only if too much rocuronium given - to overcome large overdose
Encapsulates steroid portion of relaxant
Rescue reversal - within 1.5mins
Very expensive - only (currently) used in emergency situations
What is regional anaesthesia?
Regional blocks:
Transverse Abdominis Plane (TAP) blocks - one shot or with catheter
Epidural:
NEED MORE
Opioids
What is the anatomy required for epidural? spinal?
Epidural = obvs outside the dura Spinal = subdural
