52 terms

Anesthesia

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What is the goal of anesthesia
to reduce sensory awareness and to suppress reflexes sufficiently to permit surgery or procedures
What is the most potent route of administration?
inhalation
Nitrous oxide undesirable effects
very few
GI - NV - most limiting effect
risk of hypoxia but no irritation
risk of abuse
halothane
volatile liquid with good control, smooth induction and recovery
some NM blockade
Halothane issues
MAC may effect CVS by sensitizing the myocardium to chatecholamines -> dysrhythmias, vasodilation -> hypotension
increased bronchial secretions
Halothane benefits
gold standard due to kinetics in seconds
potentiates curari form drugs
Risk with halothane
malignancy hyperthermia - rare
hepatic damage with repeated exposure due to toxic metabolite
spontaneous abortion
Why is there less risk to HCP in use of anesthetics than there used to be?
now in closed circuit systems
enflurane
less soluble
less chance of dysrhythmia
MORE hypotension
more NM depression
less liver damage
nausea post op
isoflurane
less CV or resp depression than enflurane but more than halothane
miminal liver tox
malignant hyperthermia
mildly pungent
desflurane
virtually no liver tox - no metabolism
least soluble - most rapid
malignant hyperthermia
Why would desflurane's rapid recovery be bad?
if you did not have analgesia in place
When is Desflurane CI?
as sole anesthetic in CAD or if inc BP is bad
sevoflurane
nonpungent - no irritation
poorly soluble
5% metabolism
toxic compound A in closed circulatory systems
malignant hyperthermia
Post procedure considerations in inhalation agents
NV
increased pulmonary secretions
top of the nose itching
malignant hyperthermia
How do IV anesthetics work?
potentiating action of GABA
blocks NMDA/nicotinc ACh
advantages of IV anesthetics
rapid onset
controlled dosage
easy administration
Disadvantages of IV anesthetics
OD not readily corrected
no antagonists or antidote
hangover
Barbiturates (intermediate)
methohexital
thiopental
pentobarbital
barbiturates benefits
ultra short acting
very soluble - fast acting
hypnosis
Barbiturates issues
hypotension
coughing, sneezing, laryngospasm upon induction
respiratory depression
Barbiturates CI
porphyria
status asthmaticus
How do you prevent coughing upon induction with barbiturates
atropine or scopolamine
What is an alkyl phenol?
propofol
milk of amnesia
Kinetics of propofol
rapid resolution upon discontinuation
2-4 min half life
beta half life 1-3 hr
rapid recovery with less hangover
problems in propofol
hypertriglyceridemia
increased calories
significant fall in BP and rise in HR due to lipid emulsion
imidazole
etomidate
etomidate
mostly for induction and short procedures
Benefit of etomidate
Rapid onset
minimal CV and respiratory effects
Issues with etomidate
high incidence of NV and injection pain
NO ANALGESIA
reflexes remain present
inhibits cortisol
BDZ
best amnesiac effect
mainly pre op or continuous infusion in ICY
prolonged recovery
diazepam and larazepam
NOT water soluble
too slow onset
midazolam
water soluble but slower onset than barbs
flumanezil
reversal agent
requires multiple doses because shorter half life than BDZ
cyclohexylamines
ketamine
channel blocking agent
blocks nicotinic and NMDA receptors
ketamine
dissociative anesthesia - not true surgical anesthesia
dreams and hallucinations
short procedures and rapid intubations
muscle tone remains
How do you control dreams and hallucinations with ketamine?
diazepam
Opiods for anesthesia
fentanyl
sufentanyl
no amnestic properties - only NMB
respiratory depression - airway protection required
rapid onset - easy titration
When do you need NMB?
surgery if moving big muscles - anything done to Kevin
intubations
refractory ventilation
refractory status epilepticus
severe lacerations - liver
elevated intracranial pressures
What do NMBs not accomplish?
analgesia
sedation
amnesia
axiolytic
What do you need to consider in the pt receiving NMB?
analgesia
sedation
DVT prophylaxis
eye lubricant
seizue prophylaxis
How can you tell if the pt is being managed?
reflexes
HR
BP
RR
nondepolarizing vs depolarizing
non is preferred - prevents initial contraction
Ideal relaxant
dose dependent
rapid onset
no organ needed
no AEs
no active/bad metabolites
cholinesterase inhibitors
decrease effectiveness of non depolarizing agents
aminoglycosides
dec ACh relase
increases action of non depolarizing drugs
CCB
increase actions of non depolarizing agents
succinylcholine
depolarizing agent
initial contraction - inc BP
HYPERKALEMIA
combination for initial blockade
limited dosing
keep refrigerated
rocuronium bromide
90% of use
nondepolarizing
atracurium bsylate or cis atracurium
DOC for ARF, CKD, Hep failure
no organ needed for metabolism
Train of four
test of curarization
curare
An alkaloid neurotoxin that causes paralysis by blocking acetylcholine receptors in muscle.
basis for non depolarizing NMB