anaesthetics Flashcards
examples of anaesthetics (to render unconcious)
propofol
etomidate
function of propofol
anaesthetic
sedation
anti-emesis (anti-vomit)
v rapid acting - ideal for operation
adverse side effect of propofol
cause apnoea - need ventilatory equipment
hyper TG
what is etomidate used for
IV induction agent.
not used any more as it causes adrenal suppression (dampens stress response) which is not good for trauma e.g. surgery
examples of sedation/anxiolytic drugs
benzodiazepines
barbiturates
dexmeditomidine
what are barbiturates used for
anxiolytic (sedation)
seizure suppressants
sleeping aids
examples of barbiturates
thiopental - uncontrolled refractory seizures, completely knocks brain out
methohexital - lowers seizure threshold
phenobarbital - suppress seizures
anxiolytics
adverse side effect for barbiturates
bronchoconstriction in asthmatics
apnoea (need ventilation nearby)
what are benzodiazepines used for
sedative
anxiolytic
amnesic
anticonvulsant
examples of benzodiazepines
- midazolam: short acting, rapid onset
- lorazepam and temazepam (intermediate)
- diazepam (long acting)
- flunitrazepam (aka rohypnol)
- remimazolam (new, quick onset and offset)
adverse side effect of benzos
- lorazepam and diazepam cause venous irritation and thrombophlebitis
- post-operative delerium
- all can have extended effects
respiratory and cardiac side effects of benzos
- reduce muscle tone in upper airway
- lower hypoxic response
- stable CV - BP nd CO maintained
what is lorazepam used for
anticonvulsant
what are dexmedetomidines used for
sedation withdrawal (alcohol, drugs) delerium analgesia anxiolytic [v expensive - nhs don't use)
what procedure can dexmedetomidine be used for
awake craniotomy
fibreopticintubation
(sedation without respiratory distress)
what is flumazenil and when is it used
- competitive antagonist at GABA-A receptor against benzodiazepines
- used to treat a benzo overdose
adverse reaction of flumazenil
too much can cause seizures on patients on chronic benzos (e.g. diazepam for sleep)
what is ketamine used for
acute analgesia
sedation in pads (no risk of apnoea)
dissociative anaesthesia (patient is ‘out of body’)
bronchodilation
adverse reaction of ketamine
- trigger psychotic episode in schizophrenics
- elderly can react badly
- give Benzos with ket to reduce negative side effects
examples of opioids (analgesia)
morphine codeine fentanyl tramadol ramifentanil
what is morphine used for
analgesia
palliation
peri-operative
limitations of morphine
- poor bioavailability if taken oral
- takes long to work - slow BBB penetration
side effects of morphine
- constriction of pupil (both constricted = opined overdose)
- consipation
- bradycardia
- -vasodilation
- reduce ventilatory response to CO2
- resp suppression
what us fentanyl
newer, quick acting.
more potent than morphine
-few CV effects
-transfermal fentanyl for use in cancer
how is codeine adminstered and why
oral
pro drug - convert into active metabolite
what are some limitations to using codeine
people metabolise at different speeds
what is a contraindication to using codeine on a group of patients
-risk to neonate: breast feeding mothers who rapidly metabolise.
codeine spike can go through breast milk to baby.
baby can become apnoeic
what is a caution of using tramadol
- in rapid metabolisers
- cause serotonin syndrome - build up of serotonin. (antidepressants also cause build up)
what is the action of tramadol (analogue of codeine)
inhibits serotonin reuptake = dampen pain transmossopm
benefit of ramifentanil
v short acting and rapid offset
-metabolised by non-specific enzymes in blood and tissue (which is everywhere)
what is ramifentanil used for
- ICU sedation
- patient controlled analgesia in obstetrics
- pain relief during surgery
- total intravenous anaesthesia (TIVA)
what is TIVA
use of only infusions. patients who are asleep still respond to pain (i.e. raise BP) so we need to give them pain relief
what drugs are used mainly in TIVA
propofol and ramifentanil combo infusion
benefits of TIVA
- avoid anaesthetic gases
- less nausea and vomiting
- improvement for CV side effects
disadvantages of TIVA
based on algorithms - doesn’t take into account the different in people’s tolerance
-risk of awareness
which drugs do not have antagonists
barbiturates
propofol
which drugs have short acting antagonsits
naloxone
flumazenil
