intravenous sedation Flashcards
Ideal features of an iv sedation agent
anxiolytic
sedation
ease of administration
non-irritant
quick onset
quick recovery
no side effects
low cost
amnesia?
Benzodiazepines - mechanism of action
Acts on receptors in CNS to enhance effect of GABA
- prolongs time for receptor depolarisation
mimics effects of glycine on receptors
What is GABA?
an inhibitory CNS neurotransmitter
What is present in all active benzodiazepines and why?
benzene ring
allows attachment to receptors
Benzodiazepines - effects on respiratory system
respiratory depression
- CNS depression and muscle relaxation
- decreases cerebral response to carbon dioxide
synergistic relationship with other CNS depressants
= increased respiratory depression in already compromised patients
Benzodiazepines - effect on cardiovascular system
Reduced blood pressure by muscle relaxation decreasing vascular resistance
- increased heart rate as baroreceptor reflex compensates for fall in bp
Benzodiazepines - side effects
drug interactions
- other CNS depressants
- erythromycin
- antihistamines
tolerance
dependence
sexual fantasies
- important that seditionist is never alone with patient
ideal properties/features of an IV sedation agent
anxiolysis
sedation (side effect)
ease of administration
non irritant
quick onset
quick recovery
no side effects
amnesia?
low cost
Features of diazepam
first widely used BZD
insoluble in water
preparations:
- organic solvents (propylene glycol = pain on injection)
elimination half life = 43 +/- 13 hours
risk of rebound sedation
long recovery
unpredictable
midazolam (hypnovel) features
present gold standard
water soluble at Ph >4
painless on injection
midazolam preparation
5mg/5ml
midazolam is metabolised in….
the liver
midazolam half life
90-150 mins
Cannulation sites
dorsum of hand
antecubital fossa
- second choice
how to treat midazolam over sedation
Flumanezil
500mcg in 5ml
flumazenil dose
200mcg then 100mcg increments every 60 seconds until a response is seen
fumazenil downsides
shorter half life than midazolam
- 50 mins
risk of re-sedation
