IV key points Flashcards
ideal agent
anxiolysis non-irritant no SEs sedation quick onset ease of administration quick recovery low cost
BZD action
- anxiolytic
- CNS depressant
- facilitating the binding of the inhibitory neurotransmitter GABA at various GABA receptors throughout the CNS.
- prolongs time for receptor repolarisation
effects of BZDs
respiratory - resp depression
CNS - CNS depression and muscle relaxation
CV - reduce bp by muscle relaxation, increase hr due to baroreceptor reflex compensating for bp fall
SEs of BZDs
drug interactions
tolerance and dependence
- shouldn’t see in single session
sexual fantasies (rare)
disadvantages of diazepam as a sedation agent
pain on injection (coz not water soluble able)
long recovery
risk of rebound sedation
unpredicatble
midazolam prep
5mg/5ml (1mg/ml)
advantages of midazolam
painless on injection more rapid onset more potent than diazepam - less working time but safer extra-hepatic metabolism in bowel so less affected by liver disease than some quicker recovery reliable
sedation team
operator - sedationist
2nd trained person e.g. nurse
= neither can leave room
3rd person - runner and reception
roles of nurse
calm support chaperone pre and post op instruction machine safety checks monitoring recovery emergencies
role of cannula
deliver sedative agent
why is an indwelling cannula mandatory?
may be needed for emergency
more secure, rarely blocks
why shouldn’t a butterfly cannula be used?
used for taking blood - one quick use
easy but clots and obstructs
easily dislodged
flashback
bit of blood comes back into reservoir of cannula
shouldn’t be much resistance
advantages of dorsum of hand
accessible
superficial and visible
no nearby arteries/nerves/joints
disadvantages of dorsum of hand
poorly tethered - move about a bit
affected by peripheral vasoconstriction so may need to warm hand
small veins
more painful
antecubital fossa - where should you keep?
lateral to biceps tendon
advantages of antecubital fossa
larger veins, better tethered to CT
more predictably sited
less painful
less venoconstriction
disadvantages of antecubital fossa
access, joint immobilisation
potential nerve damage/intra-arterial injection
less stable
pre-sedation process
Ametop gel pre-op pulse and bp confirm - escort - travel home - responsibilities - reconfirm consent get high vol aspiration set up emergency drugs ready - flumazenil - means of ventilation
what should be done with the cannula before sedation?
flush with saline
midazolam dose
2mg bolus
1mg increments every 60s until suitable level of sedation
suitable sedation signs
slurring and slowing of speech relaxed delayed response to commands willingness to accept tx Verrill's sign Eve's sign
Verrill’s sign
ptosis - drooping eyelids
Eve’s sign
loss of motor coordination
- get pt to close eyes, arms out wide then touch nose with both fingers, often miss nose
therapeutic dose of midazolam varies with:
sleep
alcohol
stress
drugs
max midazolam dose
-15mg
- below 7.5mg in practice
- once above 7.5, must have proper justification documentation for high dose
how long useful sedation for tx do you get with midazolam?
30-45mins
flumazenil prep
500mcg/5ml
flumazenil dose
200mcg then 100mcg increments every 60s until a response is seen
don’t give too quickly as pt may become v agitated
flumazenil cautions
shorter 1/2 life than midazolam so risk of resedation
- keep pt for longer - 1-4hrs
caution in suspected BZD allergy
recovery
escort 2nd person 60mins after last increment continue monitoring (keep cannula) - write down times you give everything remove cannula (warn bruising) ensure can walk unaided give escort POIs
respiratory depression management
Stop tx deep breaths (low 90s) - talk, shake, hurt O2 - 2l/min via nasal cannulae - can continue tx with this in if O2 sats improve O2 - 5l/min via Hudson mask flumazenil (<90%) ambu bag airways
