Anaesthetics Flashcards
ASA score (american society of anaesthesiologists)
1 = normally healthy 2 = mild systemic disease, no limit to activity 3 = severe systemic disease, limitation of activity, not incapacitating 4 = incapacitating systemic disease(s) posing threat to life 5 = moribund patient (not expected to survive 24hrs) 6 = braindead patient for donor purposes
common causes of elective surgery cancellation
- current respiratory tract infection
- poor control of drug therapy
- recent MI
- poor bloodwork
- inadequate preparation
- untreated hypertension, uncontrolled AF
- logistical issues
general anaesthesia: akinesis
muscle relaxants:
- depolarising eg.suxamethonium
- non-depolarising, eg. atracurium, rocuronium, pancuronium
general anaesthesia: amnesia
- induction: induce loss of consciousness in 1 arm-brain circulation time (IV), 10-20 seconds
- last 4-10 minutes
- propofol, thiopentone, ketamine, etomidate
propofol
IV amnesia agent
- potentiates GABA-A
- AE = pain on injection (due to activation of the pain receptor
- CI in egg/soya allergy
thiopentone
IV amnesia agent
- type of barbiturate, with anticonvulsant properties
- AE = laryngospasm
maintenance amnesia agents
inhaled:
- sevoflurane 2% = most common, sweet smell, potential for addiction
- desflurane 6% = use in obesity and long surgeries, cardiovascular depressant effects
- isoflurane 1.15% = organ transplants, respiratory irritant = laryngospasm, coughing, breath holding
IV:
- propofol
7 Ps of rapid sequence inducton (RSI)
- Preparation = involves ensuring the environment is optimised, equipment is available and staff are ready
- Preoxygenation = involves the administration of high flow oxygen for 5 minutes prior to the procedure
- Pretreatment = may involve administration of opiate analgesia or a fluid bolus to counteract the hypotensive effect of anaesthesia
- Paralysis = administration of the induction agent and paralysing agent
- Protection and positioning = cricoid pressure should be applied to protect the airway following paralysis
- Placement and proof = intubation via laryngoscopy, with proof obtained (direct vision, end-tidal CO2, bilateral auscultation)
- Post-intubation management = taping or tying the endotracheal tube, initiating mechanical ventilation and sedation agents
post-operative management
- stop anaesthetic vapours
- give oxygen
- throat suction
- reverse muscle relaxation
- once breathing: inspect mouth, remove ET tube, O2 by facemask
- recovery
PATIENT risk factors for post-operative N+V
- female
- previous PONV
- anxious
- motion-sickness sufferer
- non-smoker
- obesity
ANAESTHESIA risk factors for post-operative N+V
- opiates
- etomidate
- nitrous oxide
- volatile agents
- dehydration
SURGERY risk factors for post-operative N+V
- laparotomy
- gynae
- abdominal
- neurological
- ENT/eye
management of post-op N+V
Intra-op antiemetics - ondansetron 4-8mg, dexamethasone 4-8mg Post-op antiemetics - cyclizine 50mg TDS Acupuncture point P6
dose of local anaesthetic
lidocaine
- with adrenaline = 7mg/kg
- without adrenaline = 3mg/kg
1% = 10mg/mL OR 1g/100mL
spinal vs epidural anaesthetic
SPINAL
- smaller volume of anaesthetic directly into CSF
- anaesthesia lasts 2-3 hrs with longer analgesic effect
- 5-10 mins onset
- dense block including motor
- AEs include: total spinal block, urinary retention, permanent neurological damage (v rare)
EPIDURAL
- larger vol into epidural space
- catheter can be left in to provide long term anaesthesia (up to 72 hrs)
- 15-30 minute onset
- less dense block than spinal
- AEs include: headache, total spinal block, epidural abscess/haematoma
