ACC Flashcards
3 components of anaesthesia and sedation
hypnosis
analgesia
muscle relaxant
3 types of local anaesthetic technique
- local
- regional - target specific nerves
- neuraxial - spinal/epidural
spinal anaesthesia - subarachnoid block
- needle into CSF
- bolus injected
- lasts ~ 2h
- rapid onset
layers a spinal goes through
- skin - supraspinous ligament - interspinous ligament - ligamentum flavum - dura
epidural
- catheter into extradural space
- continuous infusion
- larger doses and slower onset
- anaesthesia or analgesia
- thoracic or lumbar
mechanism of local anaesthetics
- reversibly block Na channels so inhibit action potential
- affect smaller, unmyelinated nerves first
order of block and affects of nerves affected by local anaesthetics
o B fibres - autonomic (vasodilatation)
o C and Aδ fibres - pain and temperature
o Aβ fibres - light touch and pressure
o A⍺ and Aγ fibres - motor and proprioception
use of adrenaline with local
- causes vasoconstriction which reduces bleeding and prolongs local (reduces tissue uptake)
- don’t use adrenaline in end arteries
lidocaine
- Immediate onset|15 minutes duration
- Small procedures
bupivacaine
- Regional, spinal & epidural
- 10 minute onset
- 2 hours anaesthesia|12-24 analgesia
opioids and local
used in epidurals alongside local anaesthetic for pain relief and improves the effect of locals
what is sedation
drugs given to reduce anxiety, reduce consciousness, reduce airway irritability, induce amnesia
short term sedation
- IV Midazolam
- Endoscopy
- Regional anaesthesia
long term sedation
IV propofol +/- alfentanil
IV vs inhaled hypnotic drugs
-IV has rapid onset and depresses airway reflexes, apnoea common
- inhaled has slower onset but may irritate airway (normally keep breathing)
3 inhaled hypnotics
- Isoflurane – cheapest, used for maintenance
- Desflurane – maintenance, wears off quickly
- Sevoflurane – induction and maintenance
3 IV hypnotics
- Propofol – quick, most common, also an antiemetic, fast redistribution and recovery of consciousness
- Thiopental – quick, emergency anaesthetic
- Ketamine – used in CVS instability, also analgesic
simple airways
- Airway manoeuvres – head tilt, chin lift, jaw thrust
- Facemask – basic, for bag-mask-ventilation (BMV)
- Oropharyngeal – Guedel airway device in mouth to aid BMV
- Nasopharyngeal – aids BMV, used in seizures