Anaesthetic Agents Flashcards
what are the different routes of administration of GA?
intravenous
inhalational
intramuscular
orally, very rarely
rectally, very rarely
examples of local anaesthesia?
lidocaine
bupivacaine
examples of regional anaesthesia?
spinal blocks - e.g. labour
plexus blocks (lumbar, coeliac, brachial)
what are the Guedel stages of anaesthesia?
Stage I (analgesia/disorientation): from GA induction to LOC.
Stage II (excitement/delirium): from LOC to onset of automatic breathing.
Stage III (surgical anesthesia): from onset of automatic respiration to respiratory paralysis.
Stage IV: from stoppage of respiration till death.
what is the triad of anaesthesia?
muscle block
hypnosis (induced LOC)
analgesia
can someone who is hypnosed still feel pain?
yes, hypnosis alone does not influence the ANS so physio responses to pain are intact (e.g. hr/bp rises, stress hormone release)
do all operations need muscle relaxants?
only if an intrinsic part of surgery - e.g. bowel operation, intubation
examples of induction agents?
propofol - used 90% of time
ketamine
thiopental sodium
eval propofol
cheap
widely available
quick duration and onset
no hangover effects
depresses ANS and myocardium
eval ketamine
adv: tachycardia, vasoconstriction, does not depress ANS and myocardium, more cardiostable
disadv: hallucinogenic so abuse potential
eval thiopental sodium
hangover effect (bc slow duration), myocardial depressants
why are propofol and thiopental sodium contraindicated in pt with trauma or bleeds?
they are myocardial depressants, so cause bradycardia and hypotension
when are myocardial depressants contraindicated?
in pt with haemodynamic instability (e.g. bleeds)
why is ketamine not used in cardiac patients (e.g. IHD/CF)?
diastolic period reduced due to tachycardia
so increased ischaemia and possibly necrosis
(but may use if pt is hypovolaemic)
what part of the cardiac cycle does tachycardia preferentially affect?
diastole
