Pharm ketamine Flashcards
ketamine causes a dissociation between what to structures in brain
thalamocortical (sensory) and limbic system (association)
What type state and gaze does a patient display with ketamine
cataleptic state with eyes open and slow nystagmic gaze (noncommunicative)
Can patient move with ketamine?
varying degrees of hypertonicity or purposeful movement independent of surgical stimulation (myoclonic type movements)
Is amnesia complete with ketamine?
no, give a benzo
Emergence delirium
benzo to help prevent,
no data of risk for specific population, but use cautiously in those prone to delirium ex elderly, psych disorders,
30% rate
Ketamine analgesia?
Yes, can help reduce opiate req
Chemical structure of ketamine?
phencyclidine,
2–2-cyclo-hexanone,
partially water soluble,
RACEMIC mixture,
S-enantiomer
more potent and less side effects, very expensive (Ketanest)
MOA Ketamine
Binds noncompetitively to the phencyclidine recognition site on NMDA receptors. (blocks glutamate neurotransmitter)(Stops Na influx preventing depolarization)
Exerts weak action GABAA receptor,
Other receptors: opioid, monoaminergic, muscarinic, no, seratonin, Na channels
Why does ketamine cause analgesia?
inhibits nitric oxide synthase
How does ketamine stimulate sympathetic nervous system?
Inhibits reuptake of catecholamines
Induces catecholamine release-beta 2 agonism-respiratory relaxation
pharmocokinetics ketamine
not significantly bound to plasma proteins,
extremely lipid soluble and crosses bbb,
leaves blood rapidly to be distributed to tissues,
3 compartment model of distribution,
recovery of single bolus dose is primarily redistribution,
metabolism through liver
Metabolism of ketamine
hepatic microsomal enzymes,
Demethylation of ketamine to norketamine(1/3-1/5 potency),
norketamine may contribute to prolonged effects of ketamine with repeated doses,
Norketamine is hydroxylated and then conjugated into water soluble inactive glucuronide metabolites excreted through kidneys.
What med can prolong effect of ketamine
benzos
Aminister slowly reduces resp and cv s/e
over 60 sec
CNS effects ketamine
Cerebral vasodilator (increase CBF and CMRO2)
Not recommended in pt with intracranial pathology,
considered anticonvulsant,
may cause myoclonic movement on injection
CV effects ketamine
direct myocardial depressant,
depressant effects usually masked by stimulation of SNS,
May be significant in critically ill patients with limited SNS reserve,
Significant, transient increases in systemic BP, HR, CO,
Associated with increased cardiac work and increased cardiac metabolic requirement of O2
Respiratory effects ketamine
No significant resp depression,
When alone, CO2 response preserved,
Transient hypoventilation,
Short periods of apnea with rapid administration,
RELAXES bronchial smooth muschle, may be helpful with reactive airways or bronchoconstriction,
Increased SALIVATION (use glycol or atropine)
Overall for quiz
ketamine can be opiate sparing, less resp effect, potential delirium but offset by benzos but effects potentiate resp depression
