CNS Flashcards
N2O
MAC -105% quick, smooth induction good analgesia minimal skeletal muscle relaxation stimulate sympathetic tone- maintain cvs function
elevate intracranial pressure, pneumothorax, depress bone marrow, neuropathy
Diethyl ether
inflammable, irritant giod analgesia marked skeletal muscle relaxation prolonged induction N, V, retching, eye congeetiin, sore tracheq, burns on face reflex stimulation of respiration sympathetic tone- maintain cvs function
halothane
potent (2-4/0.5-1)
relax uterus, intestine somewhat
reduce intracellular Ca, vagal stimulation- cvs functions decreased; no baroreceptor reflex- no reflex stimulation of heart
sensitize heart to Adr - arrhythmia
vasodilation (CO2)- brain; alveoli dilate - v:p mismatch
dilate bronchi - given to ASTHMA ppl
decreased urine
hepatitis
malignant hyperthermia (ryr1 )
29% METABOLISM
isoflurane
irritant less potent quicker action direct vasodilation (Coronary: steal) sympathetic stimulation uterine/sk muscle relaxation NO pupil dilation, light reflex loss no seizure - neurosurgery
desflurane
with N2O and O2 irritant low solubility- short action steeper dose response sympathetic stimulation direct vasodilation uterine, skeletal muscle relaxation
sevoflurane
I>S>D (pk, pd)
3% metabolised
quick induction/recovery
direct vd
no sympathetic stimulation- fall in bp
enflurane
seizure
thiopentone sodium iv - common induction
given with atropin, ms relaxant
ultra short acting
high lipid solubility (undissociated form)
alkaline solution - irritant- lrynx spasm
wide distribution
accumulates
redsitribution elimination 3 min, hepatic metabolism 8-12 hours
vasodilation - cvs collapse
reflex changes
vc in brain
arrhythmogenic
halothane
sympathetic stimulation
N2O, ether, isoflurane, desflurane
atropine and thiopentene
react chemically - not in same syringe
acute intermittent porphyria
thiopentone
naroanalysis
thiopentone
methohexitone sod.
more potent, quicker briefer action, EXCITEMENT common during recovery and induction
propofol i.v
unconsciousness in 15-45 secs, last for 5-10 min
propofol (with fentanyl) IV + lidocine
no airway irritation - used in asthmatics
asthmatics - general anesthetics
propofol, sevoflurane, halothane, ketamine
propofol adr
induction apnea, vasodilation, cvs normal and depression, barorelfex suppression, respiratory
acidosis, lipemia, heart failure
sympathetic stimulation
manage cvs function
etomidate
less potent anesthetic, relaxant tc
4 min action
BZD as general anesthetic
conscious sedation
diazepam iv
sedation, amnesia, unconsciousness in 5-10 min
redistribution in 15 mins - amnesia for 2 hours
diazepam running iv drip
poor analgesic
(poor) central muscle relaxant
BZD anesthesia antagonised by
flumazenil 2mg i.v
lroazepam
more potent, less irritant than diazepam - SLOW ACTING
midazolam
faster, shorter acting
more potent, less irritant
use -critical care anesthesia
ketamine
dissociative anesthesia
site of action - cortex, subcortex
SYMPATHETIC stimulation
no respiratory depression
ketamine - action duration
effect within min, recoveryin 15 min and amnesia for 2 hours
ketamine - adr
emergence delirium, hallucination, involuntary movements (increased muscle tone)
ketamine side effects
increase cerebral ((((oxygen consumption)))) and heart work
rape drug
ketamine
fentanyl
lipohilic short acting opioid analgesic (pethidine related) anesthetic awareness parasympathetic stimulation - heart rate decrease
fentanyl antagonist
naloxone
dexmedetomidine
centrally active alpha 2A agonist - sedation
downregulate sympathetic response
side effect dexmedetomidine and clonidine (alpha agonists)
dry mouth, hypotension ,bradycardia
conscious sedation
diazepam (for 1 hour), midazolam (1 hour before surgery), propofol (iv infusion), N2O, fentanyl
anesthetic and antihypertensives
BP falls
opioids, neuroleptics, MAO I, clonidine
potentiate anesthetics
halothane
sensitises heart to Adr
corticosteroids + anesthetics
cvs collapse, adrenal insuffiency
Diabetic on anesthesia
need more insulin
pre anesthetic medication
antianxiety, amnesiacs, analgesics, anticholinergics, antiemetics, acid deceaser
sedative antianxiety +fentanyl
diazepams, lorazepams, promethazine, pethidine, morphine, chlorpromazine, triflupromazine, haloperidol
amnesiac
midazolam, hyoscine
antihistaminic
promethazine
antiemetic (increase stomach emptying and LES tone)
Metoclopromide, domperidone, promethazine, hyoscine, chlorpromazine, triflupromazine, haloperidol
anticholinergic - reduce secretions, prevent bradycardia, hypotension,
atropine, hyoscine, glycopyrrolate (MAIN- antisecretory), promethazine
analgesia
morphine, pethidine, FENTANYL,
emergence delirium
ketamine, hyoscine,
antimuscarnics
bronchodilation, pupil dilation, relax LES, DRY MOUTH
neuroleptics
chlorpromazine, triflupromazine, haloperidol
PPI/H2 blockers
ranitidine, famotidine, omeprazole
antiemetics - increase stomach emptying and LES tone
metoclopromide - EPS
domperidone (no EPS side effects)
antimetics - serotonin 3 blocker
ondansetron
