Anaesthetics Flashcards
ASA grades
6 grades
1 - healthy, no smoking, minimal drinking, healthy weight
2 - mild systemic smoking, pregnancy, well controlled hypertension, well controlled diabetes
3 - severe systemic disease diabeters, poorly controlled hypertension, distant past stroke or MI, COPD, dialysis
4 - constant threat to life recent MI, recent stroke, recent stents, spesis, DIC, severely reduced ejection status
5 - not expected to survive ruptured AAA, ICH with mass effect
6 - brain dead patient prgans being removed for donation purposes
pre-op fasting
2 hours pre-anaesthetic = NBM
up to 2 hours = clear liquids
up to 4 hours = breast milk
up to 6 houirs = light meal
up to 8 hours = unrestricted
mallampati score
4 classes
class I - complete visualisation of soft palate
clas II - complete visualisation of uvula
class III - visualisation of only base of uvula
class IV - soft palate not visible at all
tx: reversal of anticoagulation for emergency surgery warfarin
prothrombin complex concentrate
(also give vitamin K)
def: malignant hyperthermia
progressive, life threatening hyperthermic reaction occuring during GA
triggered by volatile anaesthetic gases - sevoflurane, desflurane and suxamethonium (depolarising muscle relaxant0
presentation: amlignant hyperthermia
- unexplained increased HR
- increased temp
- muscle rigidity
- increased edn tidal CO2
tx: malignant hyperthermia
remove trigger
dantrolene
def: suxamethonium apnoea
- suxamethonium is depolarising muscle relaxant
- normally short duration of action and broken down by plasma cholinesterase
- pts with decreased plasma cholinesterase activity have prolonged effect of suxamethonium
rx: suxamethonium apnoea
requires post-op ventilation until muscle relaxant effects wear off
what other muscle relaxant more commonly used: suxamtheonium apnoea
rocuronium
important hx: suxamethonium apnoea
family history of anaesthetic problems (genetic)
RFs: post-op N+V
- female
- hx travel/motion sickness
- hx PONV
- anaesthesia: opioid analgesia, volatile anaesthetic agents, nitrous oxide)
- surgical: gynae, ENT and opthalmic
reducing risk: PONV
multimodal analgesia (reduce opioid dose)
antiemetic prophylaxis - ondansetron (5-HT receptor antagoist) and dexamethesone
post-op pain rules
by the clock, by the mouth and by the ladder
what does good pain releif reduce risk of
atelectasis
methods of post-op pain control
PO
PCA
epidural
rectus sheath catheters
wound infiltration catheters
peripheral nerve blocks
3 step WHO pain ladder
step 1 NON-OPIOID - pain score 1-4: paracetamol, NSADISs, COX-2 inhibitos +/- adjuvant
step 2 WEAK OPIOID - pain score 5-6: tramadol, codeine, dihydrocodeine +/- non-opioid adjuvant
step 3 STRONG OPIOID - pain score 7-10: morphine, oxycodone, fentanyl +/- non-opioid adjuvant
local anaesthetics
lidocaine 3mg/kg, max 200mg
lidocaine+adrenaline 7mg/kg, max 500mg
bupivocaine/levobupivocaine 2mg/kg, max 150mg, max 400mg in 24hrs
ropivicaine3mg/kg, max 200mg
use ideal body weight
10mg in 1ml in 1%soln
contraindications: LA
infected tissue - low pH ionises LA so cannot enter cells
spinal: dose description, area, SE
small doses as inserted intrathecally into CSF
associated with hypotension
L3/4
epidural: location, main effects
extradurally, large doses required to diffuse across dura
lumbar or thoracic region
main effects - sensory block; pain relief and urinary retention
motor block; reduced motor power
sympathetic block; hypotension
contraindications: spinal/epidural
septic patients or anticoagulated patients
higher risk of epidural abscess or haematoma
benefits v risks: spinals and epidurals
benefits: greater pain relief
opioid sparing
reduction in some respiratory complications
reduced VTE incidence
risks: analgaesia can be patchy/unilateral
reduced mobility
post-dural headache
requires urinary catheter
presentation: local anaestetic systemic toxicity (LAST)
cascade of events beginning with CNS and then CVS
* tingling tongue/lips
* light headedness
* tinnitus
* slurred speech
* muscle twitching
* loss of consiousness
* convulsions
* coma
* myocardial depression
* cardiac arrhythmias
* respiratory arrest
* ventricular arrest
