IV Anesthetics Flashcards
How is propofol cleared?
mostly hepatic with some extra hepatic in the lungs
what is gren urine from propofol caused by?
phenol excretion
what is clouding urine from propofol caused by?
uric acid excretion
How does propofol affect baroreceptor reflex?
impairs it
accoridng to one thing in apex…
Propofol affects on sezuires?
It has anticonvulsant properties, but can cause myoclonus. There are rare reports of propofol causing seizures.
PIS tx:
dc prop, pacing, PDE inhibitors, glucagon, ECMO, CRRT
waht is PIS?
Propofols long chain triglycerides (LCTs) impair oxidative phosphorylation and fatty acid metabolism. This starves cells of oxygen, particuarly skeletal muscle and cardiac muscle.
PIS symptoms
metabolic acidosis (base deficit >10)
rhabdomyolysis
enlarged for fatty liver
renal failure
hyperlipidemia
lipemia (cloudy plasma or blood may be an early sign)
Which anesthetics incease the time GABA-A channel is open?
most of them:
propofol
etomidate
etc.
which drugs increase frequency of GABA-A channel opening?
Midazolam
propofol
Fospropofol inductiondose
6.5mg/kg
fospropofol maintence dose
1.6mg/kg no sooner than every 4 min
fospropofol onset
5-13min
fospropofol doa
15-45min
fospropofol SE
genital and anal burning
fospropofol
Ketamine 2ndry mechs of action
binds to opioid, mao, serotnoni, NE, muscarinic receptors and Na channels
what is the normal agonist at ketamines primary site of action?
glutamate
ketamine induction dose
1-2mg/kg IV
opioid sparing ketamine dose
1-3mcg/kg/min
ketamine analgesia dose
0.1-0.5mcg/kg/min
IM and PO ketamine doses
IM 4-8mg/kg
PO 10mg/kg
ketamine doa
10-20min but may take 60-90min to return to full orientation
ketamine active metaboliste and is potency
norketamine
1/3 - 1/5 as potent as ketamine
when does keatmine usually not activate the SNS
doses less than 0.5mg/kg
how does ketamine affect RR after induction dose?
can cause breif period of apnea
how does ketamine affect cerebral blood flow and oxygen use?
^ CMRO2 and ^ CBF
Why should you be careful with ketamine in patients with hixtory of seizures?
it can raise EEG activity so it could cause a seizure
risk factors for emergence delirium from ketamine
> 15yrs age
female gender
dose >2mg/kg
hx personality disorder
what kind of pain does ketamine treat?
somatic > visceral
what is esketamine?
levorotaroy enatntiomer
nasal spray used for treatment resistant depression
keatmine protein binding
12% which is an outlier from other anesthetics which are all in uppper 90s
ketamine
etomidate
etomidate induction dose
0.2-0.4mg/kg
how does etomidate affect hemodynamics
“cardiac stable”
does have small decrease in BP
what drugs have an imidazole ring?
etomidate
versed
precedex?
consideration with etomidate and intubation?
it wont blunt the SNS response to laryngoscopy
etomidate on RR
mild resp depression
etomidate effect on CPP
CPP remains stable
what are the two formulation of etomidate?
propylene glycole - burns on injection
lipophilic one - no burning
does etomidate cause seizures?
Not in a patient without any history of seizures.
it does cause myoclonus
if pt has hx of seizures it can increase risk of seizure
how does etomidate cause adrenal cortical supression?
11-betahydroxylase and 17-alphahydroxylase supression
how long does a single dose of etomidate cause adrenal corticol supression?
5-8hrs
some texts say up to 24hrs
when should you avoid etomidate?
if pt is reliant on SNS
i.E sepsis and adrenal failure
PONV risk with etomidate
30-40%
sodium thiopental
sodium thiopental dose
adult: 2.5-5mg/kg
child: 5-6mg/kg
does sodium thiopental release histamine?
yes be careful in asthmatics
how does sodium thiopental affect baro receptor reflex?
it doesnt so you get reflex tachycardia from the HoTN
what happens with intrarterial injection of sodium thiopental? how do you treat it?
intense vasoconstrction and crystal formation
tx: vasodilator like phentolamine or phenoxybenzamine. or stellate ganglion block which will cause sympathectomy of uppper extremity
what are thiobarbituurates?
thiopental
have sulfur in the 2nd position
what are oxybarbiturates?
oxygen in 2nd position
methohexital
what does adding a methyl to the nitrogen on a barbiiturate do?
decreases seizure threshold and ^ potency. I.E. methohexital
what does adding a phenyl to 5th position of barbiturate do?
increase anticonvulsant effects I.E (phenobarbital)
sodium thiopental mech of action
low dose: ^ affinty for GABA at GABA - A Recptor
High dose: directly bind GABA-A Receptor
does sodium thiopental have an active metabolite?
yes, pentobarbital after high doses
what causes the decreased BP from sodium thiopental?
primarily from venodilation. 2ndary to myocardial depression
what caues more HoTN propofol or sodium thiopental?
propofol
when does thiopental provide neuroprotection?
only during focal ischemia
NOT global ischemia
how are barbiturates metabolised?
all by p450 system
Except: phenobarbital is excreted unchanged in the urine
sodium methohexital induction dose
1-1.5mg/kg
how does sodium methohexital affect seizures?
decrease the seizure threshold for better quality seizures
what drugs should be avoided in actue intermitent porphyria?
Why should they be avoided?
ketamine
etomidate
barbiiturates
ketorolac
amiodorone
birth control pills
many but not all CCBs
lidocaine (contraversial)
They induce ALA synthase
are non-inducible forms of porphyria affected by drugs?
no
what are the two types of intermitent porphyria?
acute (inducible) and
chronic (non-inducible)
what is acute intermitent porphyria?
defect in heme synthesis > accumulation of heme precursors
what are the s/s of acute intermittent porphyria?
severe admonial pain > N/V
anxiety, confusion, seizure, psyschosis, coma,
skeletal muscle weakness > resp failure
bulbar m. weakness > aspiration risk
describe anesthetic management for acute intermittent porphyria
liberal hydration
glucose supplementation ( decrease ala synthase activity)
heme arginate ( decrease ala synthase activity)
prevent hypothermia
VA, nitrous oxide, nmbs, nmb reversals, narcotics, versed, pressors, zofran, BB, are all safe
regional is not CI but many avoid becaseu may be hard to distinguish block related symptoms from acute porphyria attack
precedex onset of action?
10-20min
precedex doa?
10-30min… really??
precedex dosing?
loading dose 1mcg/kg over 10min
drip 0.4-0.7mcg/kg/hr
how does precedex affect cerebral blood flow?
decrease CBF but no chagnge in CMRO2 so it does cause cerebral uncoupling
does precedex provide reliable amnesia?
no
how does precedex affect body’s thermoregulation?
it impairs it so patient that should shiver wont
mech of action for analgesia from precedex?
alpha 2 stimulation in dorsal horn of spinal cord > decreased substance P and glutamate release
how does precedex affect evoked potentials?
it does not impair them
why is nasal/ buccal precedex useful in preop peds sedation? what is the dose?
nasal and buccal routes have high degree of availability.
3-4mcg/kg 1 hour before surgery
versed doa?
20-60min
what is this?
precedex
what is this?
versed
versed active metabolite? potency? what happens to this active metabolite?
1-hydroxymidazolam 0.5 as potent
it is rapidly conjugated to an inactive compound
versed sedation and induction doses?
sedation 0.01-0.1mg/kg
induction dose:
CV/resp affects of induction dose versed?
decreased BP SVR and resp depression
what medications potentiate resp depression when given with benzos?
opioids
How does versed affect EEG compared to other common IV anesthetics?
cannot produce isoelectric EEG and propofol and barbituates can
does versed cause any muscle relaxation? if so, how? When is this useful?
yes spinally mediated skeletal muscle relaxation. antispasmodic effect useful for patients with cerebral palsy
does versed have an imidazole ring? What does this mean?
yes. makes it hydrophilic in the vial and liophilic once injected
what to know about lorazepam?
amnesia for up to 6 hours, slow onset so its usefullness as an anticonvulsant is limited
indication for remimazolam?
induction and maintence of procedural sedation in adults for less than 30min
remimazolam doses
induction 2.5-5mg over 1 min
M: 2.5mg IV/15/15sec q 2 min
when should remimazolam dose be decreased?
hepatic dysfunction
remimazolam profile compared to propofol?
less resp depression, and more CV stability
when is remimazolam contraindicated?
dextran 40 allergy
flumazenil dose
0.2mg IV and repeat 0.1mg Q 1 min as needed
does flumazenil reverse sedation or amnesia more?
sedation
side effects of flumazenil
seizure in benzo dependent patient
flumazenil doa?
30-60min so may need to re-dose as Doa is shorter than benzo doa
